3D Model LOD Continuous Display Method, Device and Electronic Equipment

Abstract

A method, device and electronic device for continuous display of 3D model LOD provided by the present application obtain the viewpoint information of the observation object and the model information of each 3D model; when it is determined that the viewpoint information changes, based on the viewpoint information and the model information, target 3D models are screened out from the 3D models, and the initial LOD models of the target 3D models are determined; based on the initial LOD models, the viewpoint information and the screen resolution of the screen, the visualization quality of the initial LOD models is determined; based on the visualization quality of the initial LOD models and the minimum perceivable pixel number, target LOD models are determined; and the target LOD models are output through the screen, which can enable the continuity of the display when switching LOD models, improve the display effect, and further improve the user experience.

Description

Technical Field

[0001] This application belongs to the field of display technology, and particularly relates to a method, device, and electronic device for continuous display of 3D model LOD. Background Art

[0002] With the continuous development of computer graphics technology and 3D model reconstruction technology, the complexity and authenticity of 3D scenes are increasing day by day. When rendering large-scale realistic 3D scenes, in order to balance rendering efficiency and visual effects, the multi-level detail model (LOD) technology is widely used. The implementation principle of LOD is as follows: Based on the original fine 3D model, the texture information and geometric information of the model are respectively simplified, and a model with a smaller amount of data but coarser is obtained. Through multi-level operations, models with different degrees of simplification are obtained, forming a multi-level detail model from fine to coarse. When rendering, different levels of detail models with different degrees of refinement are switched according to the distance between the model and the viewpoint. When the viewpoint is far from the object, a low-detail level model is used to reduce the rendering complexity; when the viewpoint is close to the object, it is switched to a high-detail level model. However, in the related technology, when selecting the LOD model, due to the inaccurate selection of the LOD model, visual jumps are likely to occur during the level switch, seriously damaging the visual continuity and affecting the user's immersion and experience. Summary of the Invention

[0003] In view of the above problems, the embodiments of this application provide a method, device, and electronic device for continuous display of 3D model LOD, which can make the display continuous when switching the LOD model, improve the display effect, and thus improve the user experience.

[0004] In a first aspect, the embodiments of this application provide a method for continuous display of 3D model LOD, which includes:

[0005] Obtain the viewpoint information of the observation object and the model information of each 3D model;

[0006] When it is determined that the viewpoint information has changed, based on the viewpoint information and the model information, screen out the target 3D models within the viewing range from the 3D models, and determine the initial LOD model of the target 3D models;

[0007] Based on the initial LOD model, the viewpoint information, and the screen resolution of the screen, determine the visualization quality of the initial LOD model;

[0008] Based on the visualization quality of the initial LOD model and the minimum perceivable pixel number, determine the target LOD model;

[0009] Output the target LOD model through the screen.

[0010] In some embodiments, determining the visualization quality of the initial LOD model based on the initial LOD model, the viewpoint information, and a screen resolution of the screen includes:

[0011] Determine the screen pixel resolution when the initial LOD model is rendered on the screen based on the model viewpoint distance, the field of view in the viewpoint information, and the screen resolution;

[0012] A screen space geometric error in screen space is determined based on the geometric error in the node information of the initial LOD model and the screen pixel resolution, and a screen space texture error in screen space is determined based on the texture pixel resolution in the node information and the screen pixel resolution, wherein the visualization quality includes: the screen space geometric error and the screen space texture error.

[0013] In some embodiments, determining the target LOD model based on the visualization quality and the minimum perceptible pixel number of the initial LOD model includes:

[0014] When the screen space geometric error is less than or equal to the minimum perceptible pixel number, and the screen space texture error is less than or equal to 1, determining the initial LOD model as the target LOD model;

[0015] When the screen space geometry error is greater than the minimum perceptible pixel number or the screen space texture error is greater than 1, determining whether the initial LOD model has a corresponding intermediate LOD model with a fineness greater than the initial LOD model;

[0016] In the case where an intermediate LOD model exists, the visualization quality of the current intermediate LOD model is traversed in sequence, and the target LOD model is determined based on the visualization quality of the current intermediate LOD model and the minimum perceptible number of pixels, wherein, when the screen space geometry error of the current intermediate LOD model is less than or equal to the minimum perceptible number of pixels, and the screen space texture error of the current intermediate LOD model is less than or equal to 1, the current intermediate LOD model is determined to be the target LOD model, and the traversal is terminated.

[0017] In some embodiments, the method further comprises:

[0018] Adaptively adjusting the minimum perceptible pixel number based on the viewpoint information, the node information of the initial LOD model and the screen pixel resolution to obtain an adaptive minimum perceptible pixel number;

[0019] Determining a target LOD model based on the visualization quality and the minimum perceptible pixel number of the initial LOD model includes:

[0020] A target LOD model is determined based on the visualization quality of the initial LOD model and the adaptive minimum perceptible pixel number.

[0021] In some embodiments, the adaptively adjusting the minimum perceptible pixel number based on the viewpoint information, the node information of the initial LOD model and the screen pixel resolution to obtain the adaptive minimum perceptible pixel number includes:

[0022] Determining a model viewpoint distance based on the viewpoint information and the node information of the initial LOD model;

[0023] Determine the screen pixel resolution when the initial LOD model is rendered on the screen based on the model viewpoint distance, the field of view in the viewpoint information, and the screen resolution;

[0024] Calculate the content centrality according to the outer bounding sphere corresponding to the initial LOD model, the screen pixel resolution and the screen resolution;

[0025] Determining the position center of the initial LOD model based on the position of the initial LOD model in the screen when rendering;

[0026] Determining model visual attention based on the location centrality and the content centrality;

[0027] Determining the movement speed of the viewpoint relative to the initial LOD model based on the movement speed of the viewpoint in the three-dimensional space, the screen pixel resolution and the screen resolution;

[0028] An adaptive minimum perceptible pixel number is determined based on the model visual attention, the movement speed of the viewpoint relative to the initial LOD model, and the minimum perceptible pixel number.

[0029] In some embodiments, determining the target LOD model based on the visualization quality of the initial LOD model and the adaptive minimum perceptible pixel number includes:

[0030] When the screen space geometry error is less than or equal to the adaptive minimum perceptible pixel number, and the screen space texture error is less than or equal to 1, determining the initial LOD model as the target LOD model;

[0031] When the screen space geometry error is greater than the adaptive minimum perceptible pixel number or the screen space texture error is greater than 1, determining whether the initial LOD model has a corresponding intermediate LOD model with a fineness greater than the initial LOD model;

[0032] In the case where an intermediate LOD model exists, the visualization quality of the current intermediate LOD model is traversed in sequence, and the target LOD model is determined based on the visualization quality of the current intermediate LOD model and the adaptive minimum perceptible pixel number, wherein, when the screen space geometry error of the current intermediate LOD model is less than or equal to the adaptive minimum perceptible pixel number, and the screen space texture error of the current intermediate LOD model is less than or equal to 1, the current intermediate LOD model is determined to be the target LOD model, and the traversal is terminated.

[0033] In some embodiments, the method further comprises:

[0034] The minimum perceptible number of pixels perceived by the human eye is calculated based on the minimum resolution angle perceived by the human eye and the number of pixels per unit length of the screen.

[0035] In some embodiments, the viewpoint information includes: a viewing cone, the model information includes: an outer bounding sphere, and the step of selecting a target three-dimensional model within a viewing range from the three-dimensional model based on the viewpoint information and the model information includes:

[0036] Performing intersection calculation on the viewing cone and the outer surrounding sphere corresponding to each three-dimensional model to obtain a calculation result;

[0037] Based on the calculation results, it is determined whether each three-dimensional model is within the viewing range corresponding to the viewpoint, wherein:

[0038] When the calculation result indicates that an outer enclosing sphere corresponding to the three-dimensional model intersects with the viewing cone or an outer enclosing sphere corresponding to the three-dimensional model is contained by the viewing cone, it is determined that the three-dimensional model is within the viewing range.

[0039] The three-dimensional model within the field of view is determined as the target three-dimensional model.

[0040] In a second aspect, an embodiment of the present application provides a three-dimensional model LOD continuous display device, comprising:

[0041] An acquisition module, used to acquire viewpoint information of an observed object and model information of each three-dimensional model;

[0042] A first determination module is used to filter out a target three-dimensional model located within a viewing range from the three-dimensional model based on the viewpoint information and the model information when it is determined that the viewpoint information has changed, and to determine an initial LOD model of the target three-dimensional model;

[0043] A second determination module, configured to determine the visualization quality of the initial LOD model based on the initial LOD model, the viewpoint information and the screen resolution of the screen;

[0044] A third determination module is used to determine a target LOD model based on the visualization quality and the minimum perceptible pixel number of the initial LOD model;

[0045] A display module is used to output the target LOD model through the screen.

[0046] In a third aspect, an embodiment of the present application provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the method provided in the first aspect when executing the computer program.

[0047] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, the method provided in the first aspect is implemented.

[0048] In a fifth aspect, an embodiment of the present application provides a computer program product, which includes a computer program. When the computer program is executed by a processor, it is at least used to implement a method as described in any one of the first aspect or the third aspect.

[0049] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0050] The three-dimensional model LOD continuous display method provided in the embodiment of the present application obtains the viewpoint information of the observed object and the model information of each three-dimensional model; when it is determined that the viewpoint information has changed, based on the viewpoint information and the model information, a target three-dimensional model located in the field of view is screened out from the three-dimensional model, and an initial LOD model of the target three-dimensional model is determined; based on the initial LOD model, the viewpoint information and the screen resolution of the screen, the visualization quality of the initial LOD model is determined; based on the visualization quality of the initial LOD model and the minimum perceptible number of pixels, the target LOD model is determined; and the target LOD model is output through the screen, so that the continuity of the display when switching the LOD model can be achieved, the display effect is improved, and the user experience is improved.

[0051] It can be understood that the beneficial effects of the second to fifth aspects mentioned above can be found in the relevant description of the first aspect mentioned above, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0053] Figure 1 It is a schematic flowchart of a method for continuous display of 3D model LOD provided by an embodiment of the present application;

[0054] Figure 2 It is a schematic flowchart of another method for continuous display of 3D model LOD provided by an embodiment of the present application;

[0055] Figure 3 It is a schematic flowchart of a hierarchical selection criterion provided by an embodiment of the present application;

[0056] Figure 4 It is a schematic flowchart of a calculation method for visualization quality provided by an embodiment of the present application;

[0057] Figure 5 It is a schematic structural diagram of a device for continuous display of 3D model LOD provided by an embodiment of the present application;

[0058] Figure 6 It is a schematic structural diagram of another device for continuous display of 3D model LOD provided by an embodiment of the present application;

[0059] Figure 7 It is a schematic structural diagram of an electronic device provided by an embodiment of the present application. Detailed implementation manners

[0060] In the following description, specific details such as specific system structures and technologies are presented for the purpose of illustration rather than limitation, so as to thoroughly understand the embodiments of the present application. However, those skilled in the art should clearly understand that the present application can also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid unnecessary details from interfering with the description of the present application.

[0061] It should be understood that when used in the specification and appended claims of the present application, the term "comprising" indicates the presence of the described features, wholes, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or their combinations.

[0062] It should also be understood that the term "and / or" as used in the specification and appended claims of the present application refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0063] As used in the specification of the present application and the appended claims, the term "if" may be construed, depending on the context, as "when", "once", "in response to determining", or "in response to detecting". Similarly, the phrases "if determined" or "if detected" may be construed, depending on the context, to mean "once determined", "in response to determining", "once detected", or "in response to detecting".

[0064] In addition, in the description of the specification of the present application and the appended claims, the terms "first", "second", "third", etc. are used only for distinguishing descriptions and cannot be construed as indicating or implying relative importance.

[0065] The reference to "one embodiment" or "some embodiments" etc. described in the specification of the present application means that a specific feature, structure, or characteristic described in connection with the embodiment is included in one or more embodiments of the present application. Thus, the statements "in one embodiment", "in some embodiments", "in other some embodiments", "in still other embodiments", etc. that appear in different places in this specification do not necessarily all refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways.

[0066] Before introducing the method provided by the embodiments of the present application, a brief introduction to the background and technology of related technologies is given:

[0067] With the continuous development of computer graphics technology and three-dimensional model reconstruction technology, the complexity and authenticity of three-dimensional scenes are increasing day by day. When rendering large-scale realistic three-dimensional scenes, in order to balance rendering efficiency and visual effects, the multi-level detail model (LOD, Level of Detail) technology is widely used. The implementation principle of LOD is as follows: Based on the original fine three-dimensional model, the texture information and geometric information of the model are respectively subjected to corresponding simplification processing to obtain a model with a smaller data volume but coarser. Through multi-level operations, models with different degrees of simplification are obtained, forming a multi-level detail model from fine to coarse. When rendering, different levels of detail models with different degrees of fineness are switched according to the distance between the model and the viewpoint. When the viewpoint is far from the object, a low-detail level model is used to reduce the rendering complexity; when the viewpoint is close to the object, it is switched to a high-detail level model.

[0068] LOD scheduling mainly calculates the LOD visualization quality metric based on the distance between the viewpoint and the model, and then selects the LOD level. Existing visualization quality metric methods mainly use indicators such as model information entropy, model estimated rendering time, and model screen geometric error. However, these methods have the following problems:

[0069] (1) Inaccurate visualization quality measurement: It mainly considers the geometric information of the model. It is difficult to ensure the accuracy of visualization quality measurement for realistic 3D models with richer texture information, and fails to establish a connection with visual perception ability, which in turn affects the accuracy of LOD selection.

[0070] (2) Unstable rendering efficiency: The calculation of LOD visualization quality involves complex three-dimensional space geometry calculations, which is highly complex and makes it difficult to ensure the stability of rendering efficiency.

[0071] (3) Discontinuous level switching: Since the accuracy of LOD selection and the stability of rendering efficiency are difficult to guarantee, level switching is prone to visual jumps, which seriously damages visual continuity and affects the user's sense of immersion and experience.

[0072] (4) Ignoring visual perception characteristics: Failure to fully consider the importance of the model in the scene and the impact of picture motion on visual perception, resulting in poor rendering effects in certain key areas or visual focal points.

[0073] Based on the technical problems of the related art, the embodiment of the present application provides a three-dimensional model LOD continuous display method that can be applied to electronic devices. The electronic devices may include: mobile phones, tablet computers, wearable devices, augmented reality (AR) / virtual reality (VR) devices, laptop computers, ultra-mobile personal computers (UMPC), netbooks, personal digital assistants (PDA), and the embodiment of the present application does not impose any restrictions on the specific types of electronic devices.

[0074] The present application provides a method for continuously displaying LOD of a three-dimensional model. Figure 1 The present application provides a flow chart of a method for continuous display of LOD of a three-dimensional model, such as Figure 1 As shown, the method includes:

[0075] Step S101, obtaining viewpoint information of the observed object and model information of each three-dimensional model.

[0076] In the embodiment of the present application, the viewpoint information may include: screen resolution, field of view, view cone, motion speed, etc. The model information of the three-dimensional model may include: the sphere (or box) surrounding the model, the number of LOD levels, the geometric error of each LOD level relative to the original model, the texture pixel resolution of each LOD level, etc. The observed object may be a user or a camera.

[0077] In the embodiments of the present application, the viewpoint information of the observed object can be obtained through the input of the observer. The observer controls the viewing angle through a certain interaction device (such as a mouse, keyboard, gamepad, etc.), so the viewpoint information can be obtained by reading the input of these devices. For virtual reality devices such as head-mounted displays (HMDs), the motion information of the observer's head and eyes can be obtained through built-in sensors to determine the viewpoint information.

[0078] In the embodiments of the present application, 3D models are usually stored in the form of files, such as OBJ, FBX, STL, GLTF and other formats. These files contain the geometric information of the model (such as vertices, edges, faces, etc.), material information, texture information, etc. By reading these files, the detailed information of the model can be obtained. In some embodiments, the model information of the 3D model can also be obtained from a database.

[0079] Step S102, when it is determined that the viewpoint information has changed, based on the viewpoint information and the model information, filter out the target 3D models located within the viewing range from the 3D model, and determine the initial LOD model of the target 3D model.

[0080] In the embodiments of the present application, the LOD model is a representation of different levels of detail of the same object. As the observer approaches or moves away from the object, models with different levels of fineness can be used for rendering to improve the rendering efficiency and performance. The initial LOD model is the LOD model first considered during the filtering process, usually the simplest or lowest-detail model.

[0081] In the embodiments of the present application, the frustum culling algorithm can be used to determine which 3D models are within the observer's field of view, so as to filter out the 3D models within the viewing range and obtain the target 3D models. The initial LOD model corresponding to the selected models can be set. In the embodiments of the present application, the initial LOD model can be the model with the lowest level of fineness.

[0082] In the embodiments of the present application, each LOD level model can be expressed by a node. The node records the model storage path corresponding to the LOD and the corresponding description parameters. Among them, the description parameters include: the outer bounding sphere (or box) of the model, geometric error, pixel resolution, loading status, rendering status, etc. Other relevant parameters can be extended according to the actual data situation and application requirements, without limitation. The nodes are connected in a parent-child relationship according to the level of fineness. The node corresponding to the coarsest level is used as the root node, and the nodes corresponding to the finer levels are connected as child nodes in sequence until the finest level is the leaf node.

[0083] In some embodiments, if the viewpoint does not change, no processing is required.

[0084] Step S103, determine the visualization quality of the initial LOD model based on the initial LOD model, the viewpoint information, and the screen resolution of the screen.

[0085] In the embodiments of the present application, the visualization quality refers to the clarity and realism of the rendered image displayed on the screen. It is affected by various factors, including the fineness of the LOD model, the screen resolution, the texture quality, etc.

[0086] In the embodiments of the present application, the visualization quality may include the screen space geometric error and the screen space texture error.

[0087] In the embodiments of the present application, factors such as the geometric complexity of the initial LOD model, the texture resolution, the observer distance, and the screen resolution can be considered to calculate the visualization quality when the initial LOD model is rendered on the screen.

[0088] Step S104, determine the target LOD model based on the visualization quality of the initial LOD model and the minimum perceptible pixel number.

[0089] In the embodiments of the present application, the minimum perceptible pixel number is the number of display device pixels corresponding to the smallest detail change that an observer can perceive. It is used to determine when to switch to a more refined LOD model to maintain the visual quality. The target LOD model is the LOD model finally determined according to the visualization quality and performance requirements.

[0090] In the embodiments of the present application, the visualization quality of the initial LOD model and the minimum perceptible pixel number can be compared. If the visualization quality is lower than the threshold (i.e., the detail loss is too large), then switch to a more refined LOD model. Repeat this process until the target LOD model that meets the visualization quality and performance requirements is found.

[0091] In the embodiments of the present application, the target LOD model can be added to the display LOD set, and the LOD models that do not need to be displayed can be added to the hidden LOD set.

[0092] Step S105, output the target LOD model through the screen.

[0093] In the embodiments of the present application, a scheduling thread and a rendering thread can be used for scheduling and rendering. Both the scheduling thread and the rendering thread run in a multi-threaded parallel manner. The scheduling thread loads the models in the display LOD set that have not been loaded, and unloads the idle models regularly; the rendering thread converts the models in the display LOD set that are in the hidden state to the display state, and converts the models in the hidden LOD set that are in the display state to the hidden state.

[0094] The three-dimensional model LOD continuous display method provided in the embodiment of the present application obtains the viewpoint information of the observed object and the model information of each three-dimensional model; when it is determined that the viewpoint information has changed, based on the viewpoint information and the model information, a target three-dimensional model located within the field of view is screened out from the three-dimensional model, and an initial LOD model of the target three-dimensional model is determined; based on the initial LOD model, the viewpoint information and the screen resolution of the screen, the visualization quality of the initial LOD model is determined; based on the visualization quality of the initial LOD model and the minimum perceptible number of pixels, a target LOD model is determined; and outputting the target LOD model through the screen can improve the display effect, thereby improving the user experience.

[0095] In some embodiments, step S103 may be implemented by the following steps:

[0096] Step S1031, determining the screen pixel resolution when the initial LOD model is rendered on the screen based on the model viewpoint distance, the field of view in the viewpoint information, and the screen resolution.

[0097] In the implementation of this application, the model viewpoint distance is the straight-line distance between the observer (or camera) and the center point of the model. This distance affects the size of the model on the screen. The field of view (FOV) is the angular range of the observer's field of view. A smaller FOV means a smaller area seen on the screen, but with more details; a larger FOV is the opposite. Screen resolution is the number of physical pixels on the screen, usually expressed as horizontal pixels × vertical pixels.

[0098] In the embodiment of the present application, the screen pixel resolution (SPR) of the model when it is rendered on the screen is calculated based on the model viewpoint distance, the field of view angle and the screen resolution.

[0099] Step S1032, determining a screen space geometric error in the screen space based on the geometric error in the node information of the initial LOD model and the screen pixel resolution, and determining a screen space texture error in the screen space based on the texture pixel resolution in the node information and the screen pixel resolution, wherein the visualization quality includes: the screen space geometric error and the screen space texture error.

[0100] In the embodiment of the present application, the screen space geometric error (SGE) of the LOD is calculated according to the geometric error (GE) of the LOD and the screen pixel resolution (SPR), and the screen space texture error (STE) of the LOD can be calculated based on the texture pixel resolution (PR) and the screen pixel resolution (SPR). The calculation methods of the screen space geometric error and the screen space texture error are SGE = GE / SPR and STE = PR / SPR, respectively.

[0101] The quality VQ can be visualized with SGE and STE as LOD.

[0102] The method provided in the embodiment of the present application can make LOD rendering stable and efficient, quantify the visual perception of LOD model errors, and convert the LOD level selection calculation in the visualization process from complex three-dimensional space geometry calculation to screen space pixel calculation, thereby greatly reducing the calculation complexity and making LOD level selection more real-time, thereby improving the efficiency and stability of rendering and improving the accuracy of LOD model calculation.

[0103] In some embodiments, the step S104 of determining the target LOD model based on the visualization quality and the minimum perceptible pixel number (PSP) of the initial LOD model may be implemented by the following steps:

[0104] Step S1041 , when the screen space geometry error is less than or equal to the minimum perceptible pixel number, and the screen space texture error is less than or equal to 1, determining the initial LOD model as the target LOD model.

[0105] In an embodiment of the present application, if the screen space geometric error is less than or equal to the minimum perceptible number of pixels, and the screen space texture error is less than or equal to 1, where 1 is a preset texture quality threshold, indicating that the texture quality is high enough and there is no obvious blur or jaggedness, then it is determined that the initial LOD model is fine enough and can be directly used as the target LOD model.

[0106] The above can be expressed as: if VQ_SGE≤PSP and VQ_STE≤1, the LOD level is appropriate.

[0107] Step S1042, when the screen space geometry error is greater than the minimum perceptible pixel number or the screen space texture error is greater than 1, determine whether the initial LOD model has a corresponding intermediate LOD model with a fineness greater than the initial LOD model.

[0108] In an embodiment of the present application, if the visualization quality of the initial LOD model does not meet the requirements (i.e., the screen space geometry error is greater than the minimum perceptible number of pixels, or the screen space texture error is greater than 1), it is necessary to check whether there is an intermediate LOD model that is finer than the initial LOD model.

[0109] In the embodiment of the present application, the intermediate LOD models refer to models whose level of refinement is between the initial LOD model and the target LOD model (if any).

[0110] Step S1042, in the case where an intermediate LOD model exists, traverse the visualization quality of the current intermediate LOD model in sequence, and determine the target LOD model based on the visualization quality of the current intermediate LOD model and the minimum perceptible number of pixels, wherein, when the screen space geometry error of the current intermediate LOD model is less than or equal to the minimum perceptible number of pixels, and the screen space texture error of the current intermediate LOD model is less than or equal to 1, determine that the current intermediate LOD model is the target LOD model, and end the traversal.

[0111] In an embodiment of the present application, if there are intermediate LOD models, it is necessary to traverse and calculate the visualization quality of these models in sequence, including their screen space geometry error and screen space texture error. Then, it is determined whether the current intermediate LOD model is most suitable as the target LOD model based on these errors and the minimum perceptible pixel number. If the screen space geometry error of the current intermediate LOD model is less than or equal to the minimum perceptible pixel number, and the screen space texture error of the current intermediate LOD model is less than or equal to 1, the current intermediate LOD model is determined to be the target LOD model, and the traversal ends.

[0112] In some embodiments, if a more refined intermediate LOD model does not exist, the initial LOD model is determined as the target model.

[0113] The method provided in the embodiment of the present application can select a suitable target LOD model and quantify the visual perception of the LOD model error, so that the number of pixels occupied by the rendered content that changes before and after the LOD level switching on the screen is less than the minimum number of pixels that can be distinguished by the human eye, so that the changes in the rendering content caused by the level switching will not be visually perceived, thereby maintaining the visual continuity of the level switching process.

[0114] The method provided in the embodiment of the present application can make the LOD rendering result have better visual clarity. The visual perception of the LOD model error is quantified and calculated, so that the number of pixels occupied by the model error on the screen during LOD rendering is less than the minimum number of pixels that can be distinguished by human vision, so that the model error will not be visually perceived, and the rendering result has better visual clarity.

[0115] In some embodiments, before step S104, the method further includes:

[0116] The minimum perceptible pixel number is adaptively adjusted based on the viewpoint information, the node information of the initial LOD model and the screen pixel resolution to obtain an adaptive minimum perceptible pixel number.

[0117] Step S104 includes:

[0118] A target LOD model is determined based on the visualization quality of the initial LOD model and the adaptive minimum perceptible pixel number.

[0119] In the embodiment of the present application, the adaptive adjustment of the minimum perceptible pixel number based on the viewpoint information, the node information of the initial LOD model and the screen pixel resolution to obtain the adaptive minimum perceptible pixel number can be achieved by the following steps:

[0120] Step S1, determining the model viewpoint distance based on the viewpoint information and the node information of the initial LOD model.

[0121] Step S2, determining the screen pixel resolution when the initial LOD model is rendered on the screen based on the model viewpoint distance, the field of view in the viewpoint information, and the screen resolution.

[0122] In the embodiment of the present application, the screen pixel resolution is represented by SPR.

[0123] Step S3, calculating the content centrality according to the outer bounding sphere corresponding to the initial LOD model, the screen pixel resolution and the screen resolution.

[0124] In the embodiment of the present application, the model content centrality (CC) is calculated based on the LOD outer bounding sphere (radius R), screen pixel resolution (SPR) and screen resolution (width and height are X and Y respectively). The calculation method is , which is the ratio of the model screen size to the screen diagonal when rendered. The value range of content centrality is [0, 1]. If the pixel length occupied by the model when rendered is larger, the content centrality is higher (closer to 1), and vice versa.

[0125] Step S4, determining the position center of the initial LOD model based on the position of the initial LOD model in the screen when rendering.

[0126] In the embodiment of the present application, the position center (LC) is calculated using the radial gradient method. It is assumed that the screen center or the mouse position is the highest position center point V (LC = 1), and the screen corner farthest from V is the lowest position center point F (LC = 0). V and F are the center point and gradient decreasing boundary, respectively, and an elliptical radial gradient of the screen aspect ratio is performed. The gradient value is the model position center. The value range is [0, 1]. If the model is closer to the screen center or the mouse position when rendering, the position center is higher (closer to 1), and vice versa, it is lower (closer to 0).

[0127] Step S5: determining the model visual attention based on the location centrality and the content centrality.

[0128] In the embodiment of the present application, the model visual attention (VA) is calculated based on the content centrality (CC) and the location centrality (LC), and the calculation method is VA = (CC + LC) / 2.

[0129] Step S6, determining the movement speed of the viewpoint relative to the initial LOD model based on the movement speed of the viewpoint in the three-dimensional space, the screen pixel resolution and the screen resolution.

[0130] In an embodiment of the present application, the movement speed (VV_model) of the viewpoint relative to the initial LOD model is calculated based on the movement speed (VV_world) of the viewpoint in three-dimensional space, the model screen pixel resolution (SPR) and the screen resolution (width and height are X and Y respectively).

[0131] In the embodiment of the present application, the calculation method is , this method uses the viewpoint's movement speed in three-dimensional space (meters / frame) is converted to screen pixels based on the model screen pixel resolution (SPR) (pixels / frame), which is the speed of the viewpoint's motion relative to the model.

[0132] Step S7: determining an adaptive minimum perceptible pixel number based on the model visual attention, the movement speed of the viewpoint relative to the initial LOD model, and the minimum perceptible pixel number.

[0133] In the embodiment of the present application, the minimum perceptible pixel number (PSP) is calculated based on the model visual attention (VA) and the movement speed of the viewpoint relative to the model (VV_model). 0 ) is adaptively adjusted considering visual attention and viewpoint motion, and the calculation method is , where a and b are constant parameters, a takes the value of 1, and b takes the value range of [0.5, 1].

[0134] The method provided in the embodiment of the present application can make the selected model more accurate and further improve the effect of model display by adaptively adjusting the minimum perceptible pixel number.

[0135] In some embodiments, determining the target LOD model based on the visualization quality of the initial LOD model and the adaptive minimum perceptible pixel number includes:

[0136] When the screen space geometry error is less than or equal to the adaptive minimum perceptible pixel number, and the screen space texture error is less than or equal to 1, determining the initial LOD model as the target LOD model;

[0137] When the screen space geometry error is greater than the adaptive minimum perceptible pixel number or the screen space texture error is greater than 1, determining whether the initial LOD model has a corresponding intermediate LOD model with a fineness greater than the initial LOD model;

[0138] In the case where an intermediate LOD model exists, the visualization quality of the current intermediate LOD model is traversed in sequence, and the target LOD model is determined based on the visualization quality of the current intermediate LOD model and the adaptive minimum perceptible pixel number, wherein, when the screen space geometry error of the current intermediate LOD model is less than or equal to the adaptive minimum perceptible pixel number, and the screen space texture error of the current intermediate LOD model is less than or equal to 1, the current intermediate LOD model is determined to be the target LOD model, and the traversal is terminated.

[0139] In an embodiment of the present application, the LOD level selection criterion (C) is determined based on the adaptive minimum perceptible pixel number (PSP) and the LOD visualization quality (VQ), and the level selection criterion is as follows: if VQ_SGE≤PSP and VQ_STE≤1 are satisfied, the LOD level fineness is appropriate, and the initial LOD model is selected as the target model.

[0140] In some embodiments, before step S101, the method further includes:

[0141] The minimum perceptible number of pixels perceived by the human eye is calculated based on the minimum resolution angle perceived by the human eye and the number of pixels per unit length of the screen.

[0142] In the embodiment of the present application, the minimum perceptible number of pixels is calculated based on the number of pixels per unit length of the screen (Pixels Per Inch, PPI) and the minimum resolution angle of human visual perception (1 minute angle).

[0143] In some embodiments, the pixel count per unit length (PPI) of the screen, the distance between the human eye and the screen (d), and the minimum resolution angle of human visual perception ( ) calculates the minimum perceptible pixel number (PSP 0 ), which represents the smallest detail that the human eye can distinguish from the screen rendering result. The calculation method is .

[0144] In some embodiments, step S102 includes:

[0145] Step S1021, performing intersection calculation on the view cone and the outer enclosing sphere corresponding to each three-dimensional model to obtain a calculation result.

[0146] In an embodiment of the present application, the viewpoint information includes: a viewing cone, the model information includes: an outer enclosing sphere, and determining whether each three-dimensional model is within the field of view corresponding to the viewpoint based on the viewpoint information and the model information includes: performing intersection calculations on the viewing cone and the outer enclosing spheres corresponding to each three-dimensional model to obtain calculation results.

[0147] Step S1022: determining whether each three-dimensional model is within the viewing area corresponding to the viewpoint based on the calculation result.

[0148] In an embodiment of the present application, when the calculation result represents that the outer enclosing sphere corresponding to the three-dimensional model intersects with the viewing cone or the outer enclosing sphere corresponding to the three-dimensional model is contained by the viewing cone, the three-dimensional model is determined to be within the field of view; if the calculation result represents that the outer enclosing sphere corresponding to the three-dimensional model does not intersect with the viewing cone, the three-dimensional model is determined to be not within the field of view.

[0149] Step S1022: determine the three-dimensional model within the viewing area as the target three-dimensional model.

[0150] In the embodiment of the present application, if it is not within the field of view, the LOD level node currently displayed by the model is added to the hidden LOD set, and the LOD model in the hidden LOD set is not displayed.

[0151] Based on the above embodiments, the present application further provides a method for continuously displaying LOD of a three-dimensional model. Figure 2 A flow chart of another method for continuously displaying LOD of a three-dimensional model provided in an embodiment of the present application is shown as follows: Figure 2 As shown, including:

[0152] Step S201, program initialization.

[0153] In the embodiment of the present application, the 3D scene index is read, the viewpoint information is initialized (including the initial position, the view cone, and the screen resolution), and the screen pixel count per unit length (PPI), the distance from the human eye to the screen (d), and the minimum resolution angle of human visual perception ( ) calculates the minimum perceptible pixel number (PSP 0 ), the minimum perceptible pixel number represents the smallest detail that the human eye can distinguish from the screen rendering result. The calculation formula is: .

[0154] Step S202: acquiring three-dimensional scene information.

[0155] In the embodiment of the present application, the real-time information of the 3D scene index and the viewpoint can be obtained. After the acquisition, it is necessary to determine whether the viewpoint information has changed. If it has not changed, no processing is performed; if it has changed, step S203 is executed.

[0156] Step S203, determining whether the model is within the viewing frustum.

[0157] In the embodiment of the present application, the outer bounding sphere and the view cone information of the three-dimensional model in the scene index are used to determine whether each three-dimensional model is within the field of view. If it is not within the field of view, the currently displayed LOD level node of the model is added to the hidden LOD set; if it is within the field of view, the coarsest LOD level node of the model is determined (the same as the initial LOD model in the above embodiment).

[0158] In the embodiment of the present application, if yes, execute step S204, if not, execute step S205.

[0159] Step S204: LOD level selection criteria calculation.

[0160] In the embodiment of the present application, according to the model node information, viewpoint information and the minimum perceptible pixel number (PSP 0 ), calculate the LOD level selection criterion C of the model.

[0161] Figure 3 A schematic diagram of a process flow of a hierarchical selection criterion provided in an embodiment of the present application, such as Figure 3 As shown, including:

[0162] Step 301: Obtain information.

[0163] Get LOD node information, viewpoint information and minimum perceptible pixel number (PSP 0 ).

[0164] Step S302, calculation of screen pixel resolution.

[0165] Calculate the screen pixel resolution (SPR) when the model is rendered on the screen based on the model viewpoint distance, field of view angle, and screen resolution.

[0166] Step S303: calculating content centrality.

[0167] Based on the LOD outer bounding sphere (radius R), the model screen pixel resolution (SPR) and the screen resolution (width and height are X and Y respectively), the model content center (CC) is calculated using the following method: , which is the ratio of the model screen size to the screen diagonal when rendered. The value range is [0, 1]. If the pixel length occupied by the model when rendered is larger, the content centrality is higher (closer to 1), otherwise it is lower (closer to 0).

[0168] Step S304, location centrality calculation.

[0169] The model position center (LC) is calculated based on the position of the model on the screen when it is rendered. The radial gradient method is used for calculation: Assume that the center of the screen or the mouse position is the highest position center point V (LC = 1), and the screen corner farthest from V is the lowest position center point F (LC = 0). With V and F as the center point and gradient decreasing boundary, respectively, an elliptical radial gradient of the screen aspect ratio is performed, and the gradient value is the model position center. The value range is [0, 1]. The closer the model is to the center of the screen or the mouse position when it is rendered, the higher the position center (the closer to 1), and vice versa. The lower it is (the closer to 0).

[0170] Step S305: calculating visual attention.

[0171] The model visual attention (VA) is calculated based on the model content centrality (CC) and location centrality (LC). The calculation method is VA = (CC + LC) / 2. Here, CC and LC are set to have equal weights. The weights of CC and LC can be adjusted according to actual needs.

[0172] Step S306, visual motion speed calculation.

[0173] According to the viewpoint's movement speed in three-dimensional space (VV_world), the model screen pixel resolution (SPR) and the screen resolution (width and height are X and Y respectively), the viewpoint's movement speed relative to the model (VV_model) is calculated. The calculation method is , this method uses the viewpoint's movement speed in three-dimensional space (meters / frame) is converted to screen pixels based on the model screen pixel resolution (SPR) (pixels / frame), which is the speed of the viewpoint's motion relative to the model.

[0174] Step S307, adjusting the minimum perceptible pixel number.

[0175] According to the model visual attention (VA) and the speed of the viewpoint relative to the model (VV_model), the minimum perceptible pixel number (PSP 0 ) is adaptively adjusted considering visual attention and viewpoint motion, and the calculation method is , where a and b are constant parameters, a takes the value of 1, and b takes the value range of [0.5, 1].

[0176] Step S308, LOD level selection criteria.

[0177] According to the adaptive minimum perceptible pixel number (PSP) and LOD visualization quality (VQ), the LOD level selection criterion (C) is determined as follows: If VQ_SGE≤PSP and VQ_STE≤1 are satisfied, the LOD level fineness is appropriate.

[0178] Step S206, LOD level visualization quality calculation.

[0179] In the embodiment of the present application, the visualization quality VQ of the LOD level is calculated based on the model node information, viewpoint information and screen resolution.

[0180] Figure 4 A flow chart of a method for calculating visualization quality provided in an embodiment of the present application is shown as follows: Figure 4 As shown, including:

[0181] Step S401, obtaining LOD node information and viewpoint information.

[0182] Step S402, calculating the screen pixel resolution (SPR) of the model when it is rendered on the screen according to the model viewpoint distance, the field of view angle and the screen resolution.

[0183] Step S403 , calculating the LOD screen space geometric error (SGE) and the LOD screen space texture error (STE) according to the LOD geometric error (GE), the texture pixel resolution (PR) and the screen pixel resolution (SPR).

[0184] The calculation methods are SGE = GE / SPR and STE = PR / SPR respectively.

[0185] Step S404, using SGE and STE as LOD visualization quality VQ.

[0186] Step S207: whether the level is appropriate.

[0187] In an embodiment of the present application, it can be determined whether the visualization quality VQ of the LOD level meets the LOD level selection criterion C. If so, the LOD level node is added to the display LOD set; if not, it is determined whether there is a finer LOD level. If so, step S206 is executed based on the next finer LOD level node. If not, the LOD level node is added to the display LOD set.

[0188] In the embodiment of the present application, if yes, execute step S208, and if no, execute step S209.

[0189] Step S209, determining whether there is a finer level.

[0190] In the embodiment of the present application, if yes, execute step S206, and if no, execute step S208.

[0191] Step S205, adding a hidden LOD set.

[0192] Step S208, adding the display LOD set.

[0193] In the embodiment of the present application, after step S205 and step S206, step S210 is executed.

[0194] Step S210: multi-thread dynamic scheduling.

[0195] In the embodiment of the present application, the display LOD set and the hidden LOD set are scheduled and rendered. The scheduling thread loads the models that have not been loaded in the display LOD set and regularly unloads the idle models; the rendering thread converts the models in the display LOD set that are in a hidden state to a display state, and converts the models in the hidden LOD set that are in a displayed state to a hidden state.

[0196] Step S211: updating the scene index.

[0197] In the embodiment of the present application, the hierarchical relationship, loading status and rendering status of each LOD hierarchical model in the three-dimensional scene are updated in real time.

[0198] The method provided by the embodiment of the present application can make the LOD level scheduling maintain visual continuity, establish the relationship between the LOD model error and the visual perception and resolution ability of the human eye, effectively reduce the visual jump phenomenon when the LOD level is switched, improve the visual continuity of the LOD rendering of the three-dimensional scene, and provide users with a smoother and more natural visual experience, and enhance the user's sense of immersion. It can make the LOD rendering result have better visual clarity, establish the relationship between the LOD fineness and the visual perception and resolution ability of the human eye, so that the model error of the LOD relative to the original model will not be visually perceived, and the rendering result has better visual clarity. It can make the LOD level selection more real-time, quantify the visual perception of the LOD model error, convert the LOD level selection calculation from complex three-dimensional space geometry calculation to screen space pixel calculation, reduce unnecessary calculation overhead, and improve rendering efficiency under the premise of ensuring visual effects. It can more intelligently control the fineness of the LOD level scheduling according to the user's visual attention, use a LOD level model with a higher degree of fineness in the visual attention area, and use a LOD level model with a lower degree of fineness in the visual attention area, and improve rendering efficiency under the premise of ensuring visual effects. It can more intelligently control the precision of LOD level scheduling according to the picture movement situation. For 3D models with faster picture movement speed, a less refined LOD level model is used to reduce rendering complexity and improve rendering efficiency.

[0199] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0200] According to the aforementioned embodiments, the embodiments of the present application provide a three-dimensional model LOD continuous display device, and the modules included in the device, as well as the units included in each module, can be implemented by a processor in a computer device; of course, they can also be implemented by a specific logic circuit; in the implementation process, the processor can be a central processing unit (CPU, Central Processing Unit), a microprocessor (MPU, Microprocessor Unit), a digital signal processor (DSP, Digital Signal Processing) or a field programmable gate array (FPGA, Field Programmable Gate Array), etc.

[0201] The present application embodiment provides a three-dimensional model LOD continuous display device, Figure 5 A schematic diagram of a three-dimensional model LOD continuous display device provided in an embodiment of the present application is shown in FIG. Figure 5 As shown, the three-dimensional model LOD continuous display device 500 includes:

[0202] An acquisition module 501 is used to acquire viewpoint information of an observed object and model information of each three-dimensional model;

[0203] A first determining module 502 is used for, when it is determined that the viewpoint information has changed, filtering out a target three-dimensional model located within a viewing range from the three-dimensional model based on the viewpoint information and the model information, and determining an initial LOD model of the target three-dimensional model;

[0204] A second determination module 503, configured to determine the visualization quality of the initial LOD model based on the initial LOD model, the viewpoint information and the screen resolution of the screen;

[0205] A third determination module 504 is used to determine a target LOD model based on the visualization quality and the minimum perceptible pixel number of the initial LOD model;

[0206] The display module 505 is used to output the target LOD model through the screen.

[0207] In some embodiments, the second determining module includes:

[0208] A first determining unit, configured to determine a screen pixel resolution when the initial LOD model is rendered on the screen based on a model viewpoint distance, a field of view angle in the viewpoint information, and the screen resolution;

[0209] a second determination unit, configured to determine a screen space geometric error in the screen space based on the geometric error in the node information of the initial LOD model and the screen pixel resolution, and to determine a screen space texture error in the screen space based on the texture pixel resolution in the node information and the screen pixel resolution, wherein the visualization quality comprises: the screen space geometric error and the screen space texture error.

[0210] In some embodiments, the third determination module includes:

[0211] A third determining unit, configured to determine that the initial LOD model is a target LOD model when the screen space geometric error is less than or equal to the minimum perceptible pixel number and the screen space texture error is less than or equal to 1;

[0212] A fourth determining unit, configured to determine whether the initial LOD model has a corresponding intermediate LOD model with a fineness greater than the initial LOD model when the screen space geometric error is greater than the minimum perceptible pixel number or the screen space texture error is greater than 1;

[0213] The fifth determination unit is used to traverse the visualization quality of the current intermediate LOD model in sequence when an intermediate LOD model exists, and determine the target LOD model based on the visualization quality of the current intermediate LOD model and the minimum perceptible number of pixels, wherein, when the screen space geometry error of the current intermediate LOD model is less than or equal to the minimum perceptible number of pixels and the screen space texture error of the current intermediate LOD model is less than or equal to 1, the current intermediate LOD model is determined to be the target LOD model and the traversal is terminated.

[0214] In some embodiments, the 3D model LOD continuous display device 500 further includes:

[0215] An adaptive adjustment module, used for adaptively adjusting the minimum perceptible pixel number based on the viewpoint information, the node information of the initial LOD model and the screen pixel resolution to obtain an adaptive minimum perceptible pixel number;

[0216] The third determination module includes:

[0217] A sixth determining unit is used to determine a target LOD model based on the visualization quality of the initial LOD model and the adaptive minimum perceptible pixel number.

[0218] In some embodiments, the adaptive adjustment module includes:

[0219] a seventh determining unit, configured to determine a model viewpoint distance based on the viewpoint information and the node information of the initial LOD model;

[0220] an eighth determining unit, configured to determine a screen pixel resolution when the initial LOD model is rendered on a screen based on the model viewpoint distance, the field of view in the viewpoint information, and the screen resolution;

[0221] A first calculation unit, configured to calculate the content centrality according to an outer bounding sphere corresponding to the initial LOD model, the screen pixel resolution, and the screen resolution;

[0222] A second calculation unit, configured to determine the position center of the initial LOD model based on the position of the initial LOD model in the screen when rendering;

[0223] A ninth determining unit, configured to determine a model visual attention based on the location centrality and the content centrality;

[0224] a tenth determining unit, configured to determine a movement speed of the viewpoint relative to the initial LOD model based on a movement speed of the viewpoint in the three-dimensional space, the screen pixel resolution, and the screen resolution;

[0225] An eleventh determining unit is used to determine an adaptive minimum perceptible pixel number based on the model visual attention, the movement speed of the viewpoint relative to the initial LOD model, and the minimum perceptible pixel number.

[0226] In some embodiments, the third determination module includes:

[0227] A twelfth determining unit, configured to determine that the initial LOD model is a target LOD model when the screen space geometric error is less than or equal to the adaptive minimum perceptible pixel number and the screen space texture error is less than or equal to 1;

[0228] A thirteenth determining unit is used to determine whether the initial LOD model has a corresponding intermediate LOD model with a fineness greater than the initial LOD model when the screen space geometric error is greater than the adaptive minimum perceptible pixel number or the screen space texture error is greater than 1;

[0229] The fourteenth determination unit is used to, in the case where an intermediate LOD model exists, sequentially traverse the visualization quality of the current intermediate LOD model, and determine the target LOD model based on the visualization quality of the current intermediate LOD model and the adaptive minimum perceptible pixel number, wherein, when the screen space geometry error of the current intermediate LOD model is less than or equal to the adaptive minimum perceptible pixel number, and the screen space texture error of the current intermediate LOD model is less than or equal to 1, determine that the current intermediate LOD model is the target LOD model, and end the traversal.

[0230] In some embodiments, the 3D model LOD continuous display device 500 further includes:

[0231] The calculation module is used to calculate the minimum perceptible number of pixels perceived by the human eye based on the minimum resolution angle of the human eye's visual perception and the number of pixels per unit length of the screen.

[0232] In some embodiments, the viewpoint information includes: a view cone, the model information includes: an outer bounding sphere, and the first determination module includes:

[0233] A calculation unit, used for performing intersection calculation on the view cone and the outer surrounding sphere corresponding to each three-dimensional model to obtain a calculation result;

[0234] A fifteenth determining unit is used to determine whether each three-dimensional model is within the visual range corresponding to the viewpoint based on the calculation result, wherein the three-dimensional model is determined to be within the visual range when the calculation result indicates that an outer enclosing sphere corresponding to the three-dimensional model intersects with the visual cone or the outer enclosing sphere corresponding to the three-dimensional model is contained by the visual cone;

[0235] A sixteenth determination unit is configured to determine the three-dimensional model within the field of view as a target three-dimensional model.

[0236] Based on the aforementioned three-dimensional model LOD continuous display device, the embodiment of the present application further provides a three-dimensional model LOD continuous display device, Figure 6 A schematic diagram of the structure of another three-dimensional model LOD continuous display device provided in an embodiment of the present application, such as Figure 6 As shown, including:

[0237] Initialize the module:

[0238] Responsible for initializing the 3D visualization program. Read the 3D scene index, initialize the viewpoint information (including the initial position, view cone, and screen resolution), and calculate the minimum perceptible pixel number based on the number of pixels per inch (PPI) of the screen and the minimum resolution angle of human visual perception (1 minute angle).

[0239] 3D scene information acquisition module:

[0240] Responsible for reading the real-time scene index and viewpoint information of each frame in the visualization program into the memory. The 3D model information includes the model's outer bounding sphere (or box), the number of LOD levels, the geometric error of each LOD level relative to the original model, the texture pixel resolution of each LOD level, etc.; the viewpoint information includes the screen resolution, field of view, cone, movement speed, etc.

[0241] 3D scene index maintenance module:

[0242] Responsible for real-time maintenance of the hierarchical relationship and rendering status of each LOD hierarchical model in the three-dimensional scene. In the index, each LOD hierarchical model is expressed by a node, and the node records the model storage path and corresponding description parameters corresponding to the LOD. Among them, the description parameters include: the model's outer enclosing sphere (or box), geometric error, pixel resolution, loading status, rendering status, etc. Other related parameters can be expanded according to actual data conditions and application requirements without limitation. The nodes are connected in a parent-child relationship according to the degree of refinement. The node corresponding to the coarsest level is the root node, and the nodes corresponding to the finer levels are connected downward as child nodes in sequence, until the finest level is a leaf node.

[0243] Frustum culling module:

[0244] Responsible for filtering out 3D models that are not within the field of view. By calculating the intersection of the viewing cone and the sphere surrounding the 3D model, it is determined whether the 3D model is within the field of view. If the sphere surrounding the 3D model intersects with the viewing cone or is contained by the viewing cone, the 3D model is within the field of view.

[0245] LOD level selection criteria calculation module:

[0246] Responsible for calculating the LOD level selection criteria for the 3D model. Calculate the model's visual attention and viewpoint movement speed, and calculate the 3D model LOD level selection criteria in combination with the minimum perceptible pixel number. Model visual attention refers to the user's visual attention when the 3D model is rendered. It is calculated based on the position and range of the 3D model rendered on the screen. The closer the model is to the center of the screen or the larger the screen area it occupies, the higher the visual attention. Viewpoint movement speed refers to the relative movement speed between the viewpoint and each model. The screen pixel resolution when the model is rendered is calculated based on the distance between the viewpoint and the model. The viewpoint movement speed in 3D space (meters / frame) is converted into a speed value (pixels / frame) measured in screen pixels according to the model screen pixel resolution as the movement speed of the viewpoint relative to the model.

[0247] Visual quality calculation module:

[0248] Responsible for calculating the visualization quality of LOD rendering. Taking into account the visual perception ability of the human eye, screen parameters and LOD precision, according to the rendering and visual perception of the LOD model error, the visualization quality of the LOD hierarchical model rendering result under the current viewpoint state is calculated.

[0249] LOD level selection module:

[0250] Responsible for selecting the most suitable LOD level for rendering. Considering LOD visualization quality, LOD level selection criteria and whether it is the most refined level, judge whether the LOD level is suitable for display in the current viewpoint state. Add LOD models suitable for display to the display LOD set, and add LOD models that do not need to be displayed to the hidden LOD set.

[0251] Multithreaded dynamic scheduling module:

[0252] Responsible for scheduling and rendering the LOD sets that need to be displayed and hidden. There are two types: scheduling threads and rendering threads, both of which run in multi-threaded parallel mode. The scheduling thread loads the models that have not been loaded in the display LOD set and regularly unloads the idle models; the rendering thread converts the hidden models in the display LOD set to the display state, and converts the displayed models in the hidden LOD set to the hidden state.

[0253] in addition, Figure 5 or Figure 6 The three-dimensional model LOD continuous display device shown can be a software unit, a hardware unit, or a combination of software and hardware units built into an existing electronic device, or can be integrated into the electronic device as an independent pendant, or can exist as an independent terminal device.

[0254] It should be noted that the information interaction, execution process, etc. between the above-mentioned devices / units are based on the same concept as the method embodiment of the present application. Their specific functions and technical effects can be found in the method embodiment part and will not be repeated here.

[0255] The technicians in the relevant field can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In practical applications, the above-mentioned function allocation can be completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated in a processing unit, or each unit can exist physically separately, or two or more units can be integrated in one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, which will not be repeated here.

[0256] Figure 7 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application. Figure 7As shown, the electronic device 3 of this embodiment may include: at least one processor 30 ( Figure 7 Only one processor 30 is shown in the figure), a memory 31, and a computer program 32 stored in the memory 31 and executable on at least one processor 30. When the processor 30 executes the computer program 32, the steps in any of the above-mentioned method embodiments are implemented; or, when the processor 30 executes the computer program 32, the functions of the modules / units in the above-mentioned device embodiments are implemented.

[0257] Exemplarily, the computer program 32 may be divided into one or more modules / units, one or more modules / units are stored in the memory 31, and are executed by the processor 30 to complete the present application. One or more modules / units may be a series of computer program 32 instruction segments capable of completing specific functions, and the instruction segments are used to describe the execution process of the computer program 32 in the electronic device 3.

[0258] The embodiment of the present application further provides a computer-readable storage medium, which stores a computer program 32. When the computer program 32 is executed by the processor 30, the steps in the above-mentioned method embodiments can be implemented.

[0259] An embodiment of the present application provides a computer program product. When the computer program product runs on an electronic device, the electronic device can implement the steps in the above-mentioned method embodiments when executing the computer program product.

[0260] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. According to this understanding, the present application implements all or part of the processes in the above-mentioned embodiment method, which can be completed by instructing the relevant hardware through a computer program 32. The computer program 32 can be stored in a computer-readable storage medium. When the computer program 32 is executed by the processor 30, the steps of the above-mentioned various method embodiments can be implemented. Among them, the computer program 32 includes computer program code, which can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium can at least include: any entity or device that can carry the computer program code to the terminal, a recording medium, a computer memory, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), an electric carrier signal, a telecommunication signal and a software distribution medium. For example, a USB flash drive, a mobile hard disk, a magnetic disk or an optical disk. In some jurisdictions, according to legislation and patent practice, computer-readable media cannot be electric carrier signals and telecommunication signals.

[0261] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0262] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0263] In the embodiments provided in the present application, it should be understood that the disclosed devices / network equipment and methods can be implemented in other ways. For example, the device / network equipment embodiments described above are merely schematic. For example, the division of the modules or units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0264] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0265] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

[0266] The relevant user personal information that may be involved in the various embodiments of this application is strictly in accordance with the requirements of laws and regulations, following the principles of legality, legitimacy and necessity, based on the reasonable purposes of business scenarios, to process the personal information that users actively provide during the use of products / services or generated due to the use of products / services, as well as the personal information obtained with the user's authorization.

[0267] The user personal information processed by the applicant will vary depending on the specific product / service scenario, and shall be based on the specific scenario in which the user uses the product / service, which may involve the user's account information, device information, driving information, vehicle information or other related information. The applicant will treat the user's personal information and its processing with a high degree of diligence.

[0268] The Applicant attaches great importance to the security of user personal information and has adopted reasonable and feasible security protection measures that comply with industry standards to protect user information and prevent personal information from being accessed, disclosed, used, modified, damaged or lost without authorization.

Claims

1. A three-dimensional model LOD continuous display method, characterized in that: include: Obtaining viewpoint information of the observed object and model information of each three-dimensional model; When it is determined that the viewpoint information has changed, a target three-dimensional model located within a viewing range is selected from the three-dimensional model based on the viewpoint information and the model information, and an initial level of detail LOD model of the target three-dimensional model is determined; Determining the visualization quality of the initial LOD model based on the initial LOD model, the viewpoint information and the screen resolution of the screen, wherein determining the visualization quality of the initial LOD model based on the initial LOD model, the viewpoint information and the screen resolution of the screen comprises: determining the screen pixel resolution when the initial LOD model is rendered on the screen based on the model viewpoint distance, the field of view angle in the viewpoint information and the screen resolution; determining the screen space geometric error in the screen space based on the geometric error in the node information of the initial LOD model and the screen pixel resolution, and determining the screen space texture error in the screen space based on the texture pixel resolution in the node information and the screen pixel resolution, wherein the visualization quality comprises: the screen space geometric error and the screen space texture error; Calculating the minimum perceptible number of pixels perceived by the human eye based on the minimum resolution angle perceived by the human eye and the number of pixels per unit length of the screen; Determine a target LOD model based on the visualization quality and the minimum perceptible pixel number of the initial LOD model; The target LOD model is output through the screen.

2. The method according to claim 1, characterized in that The determining of the target LOD model based on the visualization quality and the minimum perceptible pixel number of the initial LOD model comprises: When the screen space geometric error is less than or equal to the minimum perceptible pixel number, and the screen space texture error is less than or equal to 1, determining the initial LOD model as the target LOD model; When the screen space geometry error is greater than the minimum perceptible pixel number or the screen space texture error is greater than 1, determining whether the initial LOD model has a corresponding intermediate LOD model with a fineness greater than the initial LOD model; In the case where an intermediate LOD model exists, the visualization quality of the current intermediate LOD model is traversed in sequence, and the target LOD model is determined based on the visualization quality of the current intermediate LOD model and the minimum perceptible number of pixels, wherein, when the screen space geometry error of the current intermediate LOD model is less than or equal to the minimum perceptible number of pixels, and the screen space texture error of the current intermediate LOD model is less than or equal to 1, the current intermediate LOD model is determined to be the target LOD model, and the traversal is terminated.

3. The method according to claim 1, characterized in that The method further comprises: Adaptively adjusting the minimum perceptible pixel number based on the viewpoint information, the node information of the initial LOD model and the screen pixel resolution to obtain an adaptive minimum perceptible pixel number; Determining a target LOD model based on the visualization quality and the minimum perceptible pixel number of the initial LOD model includes: A target LOD model is determined based on the visualization quality of the initial LOD model and the adaptive minimum perceptible pixel number.

4. The method according to claim 3, characterized in that The step of adaptively adjusting the minimum perceptible pixel number based on the viewpoint information, the node information of the initial LOD model and the screen pixel resolution to obtain an adaptive minimum perceptible pixel number includes: Determining a model viewpoint distance based on the viewpoint information and the node information of the initial LOD model; Determine the screen pixel resolution when the initial LOD model is rendered on the screen based on the model viewpoint distance, the field of view in the viewpoint information, and the screen resolution; Calculate the content centrality according to the outer bounding sphere corresponding to the initial LOD model, the screen pixel resolution and the screen resolution; Determining the position center of the initial LOD model based on the position of the initial LOD model in the screen when rendering; Determining model visual attention based on the location centrality and the content centrality; Determining the movement speed of the viewpoint relative to the initial LOD model based on the movement speed of the viewpoint in the three-dimensional space, the screen pixel resolution and the screen resolution; An adaptive minimum perceptible pixel number is determined based on the model visual attention, the movement speed of the viewpoint relative to the initial LOD model, and the minimum perceptible pixel number.

5. The method according to claim 3, characterized in that: The determining of the target LOD model based on the visualization quality of the initial LOD model and the adaptive minimum perceptible pixel number includes: When the screen space geometry error is less than or equal to the adaptive minimum perceptible pixel number, and the screen space texture error is less than or equal to 1, determining the initial LOD model as the target LOD model; When the screen space geometry error is greater than the adaptive minimum perceptible pixel number or the screen space texture error is greater than 1, determining whether the initial LOD model has a corresponding intermediate LOD model with a fineness greater than the initial LOD model; In the case where an intermediate LOD model exists, the visualization quality of the current intermediate LOD model is traversed in sequence, and the target LOD model is determined based on the visualization quality of the current intermediate LOD model and the adaptive minimum perceptible pixel number, wherein, when the screen space geometry error of the current intermediate LOD model is less than or equal to the adaptive minimum perceptible pixel number, and the screen space texture error of the current intermediate LOD model is less than or equal to 1, the current intermediate LOD model is determined to be the target LOD model, and the traversal is terminated.

6. The method according to claim 1, characterized in that The viewpoint information includes: a viewing cone, the model information includes: an outer bounding sphere, and the step of selecting a target three-dimensional model located within a viewing range from the three-dimensional model based on the viewpoint information and the model information includes: Performing intersection calculation on the viewing cone and the outer surrounding sphere corresponding to each three-dimensional model to obtain a calculation result; Based on the calculation results, it is determined whether each three-dimensional model is within the viewing range corresponding to the viewpoint, wherein: When the calculation result indicates that an outer enclosing sphere corresponding to the three-dimensional model intersects with the viewing cone or the outer enclosing sphere corresponding to the three-dimensional model is contained by the viewing cone, determining that the three-dimensional model is within the viewing range; The three-dimensional model within the field of view is determined as the target three-dimensional model.

7. A three-dimensional model LOD continuous display device, characterized in that: include: An acquisition module, used to acquire viewpoint information of an observed object and model information of each three-dimensional model; A first determination module is used to filter out a target three-dimensional model located within a viewing range from the three-dimensional model based on the viewpoint information and the model information when it is determined that the viewpoint information has changed, and to determine an initial LOD model of the target three-dimensional model; a second determination module, configured to determine the visualization quality of the initial LOD model based on the initial LOD model, the viewpoint information and the screen resolution of the screen, wherein the determination of the visualization quality of the initial LOD model based on the initial LOD model, the viewpoint information and the screen resolution of the screen comprises: determining the screen pixel resolution when the initial LOD model is rendered on the screen based on the model viewpoint distance, the field of view angle in the viewpoint information and the screen resolution; determining the screen space geometric error in the screen space based on the geometric error in the node information of the initial LOD model and the screen pixel resolution, and determining the screen space texture error in the screen space based on the texture pixel resolution in the node information and the screen pixel resolution, wherein the visualization quality comprises: the screen space geometric error and the screen space texture error; A calculation module, used for calculating the minimum perceptible number of pixels perceived by the human eye based on the minimum resolution angle perceived by the human eye and the number of pixels per unit length of the screen; A third determination module is used to determine a target LOD model based on the visualization quality and the minimum perceptible pixel number of the initial LOD model; A display module is used to output the target LOD model through the screen.

8. An electronic device, comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the method according to any one of claims 1 to 6 when executing the computer program.

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