Urban three-dimensional model digital watermarking method and system oriented to digital intellectual property

Abstract

The invention relates to the cross technical field of geographic information, data security, three-dimensional images, semantic segmentation and the like, provides a digital intellectual property-oriented urban three-dimensional model digital watermarking method and system, mainly performs blind watermarking processing on an urban three-dimensional model through a digital watermarking technology, and aims to improve the practicability. Preferably, digital watermarking processing is carried out on the material image of the terrain grid body, the terrain watermarking image is embedded into the terrain material image in a hidden mode, and digital watermarking processing can be carried out on the material images of the road grid body, the landscape grid body and the water area grid body respectively. Digital watermarking processing can be carried out through multi-dimensional carriers such as terrains, roads, landscapes and water areas in a large-scale urban scene, semantic segmentation can be carried out on the terrains through an artificial intelligence technology, and digital watermarking is set for the terrains according to different area types. According to the method, digital watermark processing of the urban three-dimensional model is realized, and data intellectual property protection, data capitalization and asset transaction utilization are facilitated.

Description

Technical Field

[0001] This application relates to the interdisciplinary fields of geographic information, data security, and 3D imaging, and proposes a method, system, and computer software product for digital watermarking of urban 3D models for digital intellectual property rights. Background Technology

[0002] With the widespread application of geographic information remote sensing data, ensuring data security and data asset copyright has become a crucial issue. Digital watermarking technology, by embedding invisible watermark information into images, is an effective and feasible solution. Digital watermarking is an information hiding technology that utilizes the limitations of human senses to embed specific digital signals into digital products to protect their copyright, integrity, prevent copying, or track their whereabouts. Common digital watermarking techniques, such as spatial domain watermarking, directly apply the watermark to the carrier data; while transform domain watermarking applies the watermark to the carrier data in the Fourier transform domain, wavelet transform domain, or other transform domains.

[0003] Currently, research on digital watermarking in the fields of remote sensing images and urban 3D models mainly focuses on algorithms for embedding watermarks into the entire image, neglecting the actual applications and needs of enterprise business development. It fails to research and understand how to maximize the value of remote sensing images and urban 3D models. For example, when using or trading data, users may perform secondary development and utilization of remote sensing images and urban 3D models, such as extracting parts of the original image as needed, or overlaying 3D models onto the original image data, thus covering the original image. These situations all destroy the original image. Even though existing digital watermarking technologies consider situations where images are cropped, rotated, or scaled, and can still achieve watermark verification to a certain extent, existing digital watermarking methods are always too simple and singular, failing to consider these practical scenarios of data application and not meeting our needs in areas such as data intellectual property assetization and asset trading. Summary of the Invention

[0004] To overcome at least one problem or deficiency in the prior art, this application proposes a method, system and computer software product for digital watermarking of urban 3D models.

[0005] I. Digital Watermarking Method for Urban 3D Models

[0006] One objective of this application is to provide a digital watermarking method for urban 3D models. The urban 3D model includes a terrain grid and a building grid. The terrain grid has several building area holes that are adapted to the building grid. The watermarking method includes the following steps: obtaining the terrain grid; obtaining a terrain material image with an embedded terrain watermark image from a terrain material library; or, implicitly embedding the terrain watermark image obtained from the watermark database into the terrain material material obtained from the terrain material library to generate a watermarked terrain material image; embedding the watermarked terrain material image into the terrain grid to generate a watermarked 3D terrain model; and embedding corresponding building grids or 3D building models into the building area holes of the watermarked 3D terrain model according to the geospatial relationship to generate a watermarked urban 3D model. The 3D building model is generated using the building grid and the building material image.

[0007] In some embodiments, the watermarking method may further include the following steps: obtaining the building mesh; obtaining a building material image with an embedded building watermark image from a building material library; or, implicitly embedding the building watermark image obtained from the watermark database into the building material material obtained from the building material library to generate a watermarked building material image; embedding the watermarked building material image into the building mesh to generate a watermarked building 3D model; and embedding the corresponding watermarked building 3D model into the building area holes of the watermarked terrain 3D model according to the geospatial location relationship to generate a watermarked city 3D model.

[0008] In some embodiments, the city 3D model further includes several indoor scene models, each corresponding to a room in the building grid; the indoor scene model includes window areas, wall areas, and / or ground areas; the watermarking method may further include the following steps: obtaining an indoor scene material image with an embedded indoor scene watermark image from an indoor scene material library, or embedding an indoor scene watermark image obtained from a watermark database into an indoor scene material obtained from an indoor scene material library to generate an indoor scene material image with an embedded indoor scene watermark image; embedding the indoor scene material image into the window areas, wall areas, and / or ground areas to generate an indoor scene 3D model containing watermark and material information.

[0009] In some embodiments, an indoor watermark image is embedded in the window area of ​​the indoor scene model; the watermarking method may further include the following steps: when a user instructs the user to view a room on the building 3D model, when the indoor scene model corresponding to the room is retrieved, the visual interface is controlled to display the corresponding indoor scene; when the indoor scene viewpoint moves to a window area, the window area is controlled to display the corresponding outdoor scene according to the viewpoint position relationship of the current indoor scene viewpoint in the city 3D scene.

[0010] In some embodiments, the watermarking method may further include a step of semantic segmentation of the terrain grid; semantic recognition of the terrain grid is performed using a trained semantic segmentation model to segment several terrain regions, wherein the terrain regions include at least one type of road region, landscape region, water region, farmland region, forest region, and wilderness region; according to the tag type of the terrain region, a corresponding terrain material image with embedded terrain watermark image is obtained from the terrain material library, or a corresponding terrain watermark image obtained from the watermark database is embedded into a corresponding terrain material material obtained from the terrain material library to generate a terrain material image with embedded terrain watermark image; the watermark database includes at least multiple tag types among road region watermark, landscape region watermark, water region watermark, farmland region watermark, forest region watermark, and wilderness region watermark.

[0011] In some embodiments, the urban 3D model includes a landscape grid, and the terrain grid has a plurality of landscape area holes adapted to the landscape grid; the watermarking method may further include the following steps: obtaining the landscape grid; obtaining a landscape material image with an embedded landscape watermark image from a landscape material library; or, implicitly embedding a landscape watermark image obtained from a watermark database into the landscape material material obtained from the landscape material library to generate a watermarked landscape material image; embedding the watermarked landscape material image into the landscape grid to generate a watermarked landscape 3D model; and embedding the corresponding landscape 3D model into the landscape area holes of the watermarked terrain 3D model according to the geospatial location relationship.

[0012] In some embodiments, the urban 3D model includes a road grid, and the terrain grid has a plurality of road area holes adapted to the road grid; the watermarking method may further include the following steps: obtaining the road grid; obtaining a road material image with an embedded road watermark image from a road material library; or, implicitly embedding a road watermark image obtained from a watermark database into the road material material obtained from the road material library to generate a watermarked road material image; embedding the watermarked road material image into the road grid to generate a watermarked road 3D model; and embedding the corresponding road 3D model into the road area holes of the watermarked terrain 3D model according to the geospatial location relationship.

[0013] In some embodiments, the city 3D model includes a water area grid, and the terrain grid has a plurality of water area holes adapted to the water area grid; the watermarking method may further include the following steps:

[0014] In some embodiments, the watermarking method may further include the following steps: obtaining the water area mesh; obtaining a water area material image with an embedded water area watermark image from a water area material library; or, implicitly embedding the water area watermark image obtained from the watermark database into the water area material material obtained from the water area material library to generate a watermarked water area material image; embedding the watermarked water area material image into the water area mesh to generate a watermarked three-dimensional water area model; and embedding the corresponding water area three-dimensional model into the water area holes of the water area in the water area three-dimensional model with the watermark, according to the geospatial location relationship.

[0015] In some embodiments, the city 3D model further includes a vegetation model, which is automatically generated in the city 3D model according to preset rules.

[0016] II. Geographic Information Data Watermarking System

[0017] One objective of this application is to provide a geographic information data watermarking system, which includes a city 3D model, a watermark embedding module, a material mapping module, a material database, a watermark database, and a synthesizer. The city 3D model includes a terrain mesh and a building mesh, with several building area holes on the terrain mesh that match the building mesh. The material database includes a terrain material library and building material images. The watermark database includes terrain watermark images. The watermark embedding module is used to acquire the terrain mesh; acquire terrain material images with embedded watermark images from the terrain material library; or, acquire terrain material images from the terrain material library... The terrain material obtained from the library will be implicitly embedded with the terrain watermark image obtained from the watermark database to generate a watermarked terrain material image; the material mapping module is used to embed the watermarked terrain material image into the terrain mesh to generate a watermarked 3D terrain model; the compositor is used to embed the corresponding building mesh or 3D building model into the building area holes of the watermarked 3D terrain model according to the geospatial relationship to generate a watermarked city 3D model; the 3D building model is generated by the building mesh and the building material image.

[0018] III. Computer program storage media

[0019] One objective of this application is to provide a computer-readable storage medium. The storage medium is used to store a computer program, and when a computer reads the computer program from the storage medium, the computer performs operations corresponding to the watermarking method described in Part One.

[0020] In summary, due to the adoption of the above technical solutions, the beneficial effects of this invention include: This invention proposes a method, system, and computer software product for digital watermarking of urban 3D models. It primarily uses digital watermarking technology to perform blind watermarking processing on urban 3D models. To improve practicality, it preferably performs digital watermarking processing on the material images of terrain grids, implicitly embedding the terrain watermark image into the terrain material image. It can also perform digital watermarking processing on the material images of road grids, landscape grids, and water grids separately, enabling digital watermarking processing in large urban scenes through multi-dimensional carriers such as terrain, roads, landscapes, and water bodies. Furthermore, it can use artificial intelligence technology to perform semantic segmentation of the terrain, setting digital watermarks for different regional zones. This application realizes digital watermarking processing for large-scale urban 3D models, which is more conducive to data intellectual property protection, data assetization, and asset trading.

[0021] It should be noted that different embodiments of this application may produce different beneficial effects. In different embodiments, the beneficial effects that may be produced may be any one or more combinations mentioned in this application, or any other beneficial effects that may be obtained that are not exhaustively described. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below.

[0023] in: Figure 1 Exemplary system block diagrams of a watermarking system shown according to some embodiments of this application; Figure 2 Exemplary system block diagrams of a watermarking system shown according to some embodiments of this application; Figure 3 Exemplary system block diagrams of a watermarking system shown according to some embodiments of this application. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and it is not possible to exhaustively describe all embodiments.

[0025] I. Digital Watermarking Method for Urban 3D Models

[0026] See Figure 1 As shown, this invention proposes a digital watermarking method for urban 3D models. The urban 3D model mainly consists of terrain grids and building grids. The terrain grids have several building area holes that are adapted to the building grids. The building grids are embedded in the building area holes of the terrain grids to form a complete urban 3D model.

[0027] In some embodiments, the watermarking method mainly includes the following steps:

[0028] S1, Obtain the terrain grid.

[0029] S2, retrieve a terrain material image with an embedded terrain watermark from the terrain material library; or, retrieve terrain material material from the terrain material library and implicitly embed the terrain watermark image obtained from the watermark database into the terrain material material to generate a watermarked terrain material image. In this application, regardless of whether it is terrain, landscape, road, or water body material image, there are generally two ways to obtain its watermarked image: one is real-time creation, which provides a visual interactive interface for users, offering information input and parameter setting bars, facilitating users to dynamically configure the watermark image in real time; the other is extraction from a pre-prepared watermarked material database according to tag type.

[0030] In some embodiments, the terrain material library includes remote sensing images, i.e., remote sensing images (RS), mainly including aerial images and satellite images, with orthophoto remote sensing images being generally preferred. The terrain material library may also include manually created material images or artificial intelligence-generated material images.

[0031] S3, embed the watermarked terrain material image into the terrain mesh to generate a watermarked 3D terrain model.

[0032] S4. Based on the geographic spatial relationship, embed the corresponding building mesh or building 3D model into the building area holes of the watermarked terrain 3D model to generate a watermarked city 3D model.

[0033] In some embodiments, this invention splits the city's 3D model into terrain meshes and building meshes. Preferably, only the terrain meshes are digitally watermarked. This avoids the problems of high processing workload and low efficiency caused by the large number and complexity of building meshes, and also prevents the watermark embedded in the building meshes from being recognized in large scene views. Since terrain meshes generally have a large area distribution in the city's 3D model, they have more space to hide the watermark and are less likely to be obscured by other models. Therefore, this invention cleverly embeds the watermark into the terrain mesh.

[0034] In some embodiments, the watermarking method includes a building watermark embedding step S6: obtaining the building mesh. A building material image with an embedded building watermark image is obtained from a building material library; or, building material materials obtained from a building material library are implicitly embedded with the building watermark image obtained from the watermark database to generate a watermarked building material image. The watermarked building material image is embedded into the building mesh to generate a watermarked 3D building model; according to the geospatial relationship, the corresponding watermarked 3D building model is embedded in the holes of the building area in the watermarked terrain 3D model to generate a watermarked city 3D model. This invention embeds watermarks on both the terrain model and the building model simultaneously, supporting verification of watermarks on the building model at close range, as well as 3D watermark verification of the building 3D model itself.

[0035] In some embodiments, the city 3D model further includes several indoor scene models, each corresponding to a room in the building mesh. Each indoor scene model includes window areas, wall areas, and / or ground areas. An indoor scene material image with an embedded indoor scene watermark image is obtained from an indoor scene material library, or an indoor scene watermark image obtained from a watermark database is embedded into an indoor scene material obtained from the indoor scene material library to generate an indoor scene material image with an embedded indoor scene watermark image. This indoor scene material image is then embedded into the window areas, wall areas, and / or ground areas to generate an indoor scene 3D model containing watermark and material information. In some embodiments, further, the window areas of the indoor scene model have an embedded indoor watermark image. When a user instructs the user to view a room on the building 3D model, the corresponding indoor scene model is retrieved, and the corresponding indoor scene is displayed on the visual interface. When the indoor scene viewpoint moves to include a window area, the corresponding outdoor scene is displayed in the window area based on the viewpoint position of the current indoor scene viewpoint in the city 3D scene.

[0036] In some embodiments, the watermarking method may further include a step of semantic segmentation of the terrain grid; semantic recognition is performed on the terrain grid using a trained semantic segmentation model to segment several terrain regions. The terrain regions include at least one type of road region, landscape region, water region, farmland region, forest region, and wilderness region. In some embodiments, the road region may be urban roads and rural roads, where urban roads may only be major traffic arteries, such as national highways and provincial highways, while narrow alleys, community roads, park roads, etc., are not considered. Specifically, in urban semantic models, the identification and segmentation of major traffic arteries are primarily focused on urban areas. The landscape region may be parks, scenic areas, open green areas, etc.; the water region may be rivers, lakes, etc.; and the wilderness region may be sandy land, barren mountains, barren rocks, barren soil, or other areas without vegetation or with low-density vegetation.

[0037] Based on the tag type of the terrain region, a corresponding terrain material image with embedded terrain watermark is obtained from the terrain material library, or a corresponding terrain watermark image obtained from the watermark database is embedded into a corresponding terrain material material obtained from the terrain material library to generate a terrain material image with embedded terrain watermark. The watermark database includes at least multiple tag types such as road area watermark, landscape area watermark, water area watermark, farmland area watermark, forest area watermark, and wilderness area watermark. The road area watermark is embedded into the road area image, the landscape area watermark into the landscape area image, the water area watermark into the water area image, the farmland area watermark into the farmland area image, the forest area watermark into the forest area image, and the wilderness area watermark into the wilderness area image.

[0038] In some embodiments, the city 3D model may further include a road grid, on which there are a number of road area holes adapted to the road grid.

[0039] The watermarking method includes the following steps: obtaining the road mesh; obtaining a road material image with an embedded road watermark image from a road material library; or, implicitly embedding the road watermark image obtained from the watermark database into the road material material obtained from the road material library to generate a watermarked road material image; embedding the watermarked road material image into the road mesh to generate a watermarked road 3D model; and embedding the corresponding road 3D model into the road area holes of the watermarked terrain 3D model according to the geospatial location relationship.

[0040] In some embodiments, the city 3D model includes a water area grid, and the terrain grid has several water area holes adapted to the water area grid. The watermarking method includes the following steps: obtaining the water area grid; obtaining a water area material image with an embedded water area watermark image from a water area material library; or, implicitly embedding a water area watermark image obtained from a water area material library into the water area material to generate a watermarked water area material image; embedding the watermarked water area material image into the water area grid to generate a watermarked 3D water area model; and embedding the corresponding water area 3D model into the water area holes of the water area 3D terrain model according to the geospatial location relationship.

[0041] like Figure 2 As shown, in some embodiments, the urban 3D module of the present invention may include terrain grids, building grids, landscape grids, road grids, water grids, indoor scene models, etc., at least including terrain grids and building grids. We can preferably embed digital watermarks on the terrain grids, or we can set watermarks on other grids besides the building grids, or we can set watermarks on all of them.

[0042] It should be noted that the focus of this application is on classifying the components of a city's 3D model and embedding digital watermarks according to these categories, thereby achieving effective watermark protection for the copyright of large-scale city 3D models. The focus of protection is not on the digital watermarking algorithm itself. The embedding of digital watermarks in this application can be a process of embedding a 2D watermark image into a 2D image. Generally, the watermark image needs to be binarized. Existing digital watermarking technologies can be used, such as digital watermarking technology based on Singular Value Decomposition (SVD), watermark embedding technology based on Discrete Cosine Transform (DCT), image hiding technology based on LSB (Least Significant Bit), image steganography technology based on pixel value difference, watermarking technology based on QR orthogonal decomposition, etc. Alternatively, self-developed digital watermarking algorithms that meet specific requirements or recognition accuracy requirements can be used.

[0043] In some embodiments, this application can also be a process of embedding a two-dimensional watermark image into a three-dimensional image. Generally, it is necessary to convert the mesh volume into a point cloud, such as converting a terrain mesh volume into a terrain point cloud, a building mesh volume into a building point cloud, a road mesh volume into a road point cloud, and so on. Binarization of the watermark image is generally required, and existing digital watermarking techniques can be used, such as algorithms based on LSB (Least Significant Bit), Singular Value Decomposition (SVD), Non-Subsampling Transform (NSCT), Discrete Cosine Transform (DCT), Fourier Transform, FFT Transform, JND (Junior Neural Network Optimization), and Arnold Transform for watermark embedding. The mapping relationship between the watermark image and the point cloud can be determined by calculating the elevation values ​​and differences between adjacent points in the three-dimensional model point cloud. The watermark image can be embedded by modifying the parity of the coordinate values, or the centroid distance between adjacent point clouds can be used for watermark embedding, etc.

[0044] For example, the watermark image can be binarized first to generate a binary image, and then the pixel positions of the binary image can be rearranged to achieve initial information hiding, so that the user cannot know the original appearance of the watermark image. The pixel position rearrangement can move the original pixel position (x,y) to a new position (x',y') according to the following formula.

[0045] x' = (ax + by) mod (L)

[0046] y'=(cx+dy)mod(L)

[0047] In the formula, a, b, c, and d are transformation coefficients, mod is the modulo operator, and L is the length of the watermark image. Usually, the watermark image is a square image with equal length and width. The coefficients can generally be a = 1, b = 1, c = 1, and d = 2.

[0048] Then, feature points are extracted from each of the point cloud images, and the watermark embedding position of each point cloud image is calculated based on the feature points. The feature point extraction can be achieved by calculating the angle and mean angle between the normal vectors of each vertex and the normal vectors of its neighboring vertices using the normal vectors of the vertices of the point cloud image, and considering vertices with a mean angle greater than or equal to a preset threshold as feature points.

[0049] II. Urban 3D Model Digital Watermarking System

[0050] like Figure 3 As shown, this application also proposes a digital watermarking system for a city 3D model corresponding to the watermarking method described in Part 1. This system has corresponding software functional modules and computer programs, capable of performing all operations corresponding to the embodiments included in the watermarking method, and also has various corresponding embodiments, which will not be described further in this section. The watermarking system mainly consists of a city 3D model, a watermark embedding module, a material mapping module, a material database, a watermark database, and a synthesizer.

[0051] The city 3D model includes a terrain grid and a building grid, and the terrain grid has several building area holes that are adapted to the building grid.

[0052] The material database includes a terrain material library and building material images.

[0053] The watermark database includes topographic watermark images.

[0054] The watermark embedding module is used to obtain the terrain mesh; obtain a terrain material image with an embedded terrain watermark image from the terrain material library; or, obtain terrain material material from the terrain material library and implicitly embed the terrain watermark image obtained from the watermark database into the terrain material material to generate a watermarked terrain material image.

[0055] The material mapping module is used to embed the watermarked terrain material image into the terrain mesh to generate a watermarked 3D terrain model.

[0056] The synthesizer is used to embed the corresponding building mesh into the building area holes of the watermarked 3D terrain model according to the geospatial location relationship, so as to generate a watermarked 3D city model.

[0057] In some embodiments, the city 3D model may include, in addition to terrain grids and building grids, any combination of road grids, landscape grids, and water grids. Correspondingly, the terrain grids contain several building area holes, road area holes, landscape area holes, and water area holes that are compatible with the building grids, road grids, landscape grids, and water grids. The terrain grids, building grids, road grids, landscape grids, and water grids can be combined to form a complete city 3D model.

[0058] This invention proposes a method, system, and computer software product for digital watermarking of urban 3D models. It primarily utilizes digital watermarking technology to perform blind watermarking on urban 3D models. To improve practicality, it preferably performs digital watermarking on the material images of terrain grids, implicitly embedding the terrain watermark image into the terrain material image. It can also perform digital watermarking on the material images of road grids, landscape grids, and water grids separately. This enables digital watermarking in large-scale urban scenes using multi-dimensional carriers such as terrain, roads, landscapes, and water bodies. Furthermore, it employs artificial intelligence technology for semantic segmentation of terrain, allowing for the setting of digital watermarks for different regional zones. This application achieves digital watermarking processing for large-scale urban 3D models, which is more conducive to data intellectual property protection, data assetization, and asset trading.

[0059] It should be noted that the above description of the system and its modules is for convenience only and should not limit this application to the scope of the embodiments described. It is understood that those skilled in the art, after understanding the principle of the system, may arbitrarily combine the various modules or construct subsystems connected to other modules without departing from this principle. The terms "system," "device," "equipment," and / or "module" used in this application are a way of distinguishing different components, elements, parts, sections, units, modules, or assemblies at different levels. However, if other terms can achieve the same purpose, they can be replaced by other expressions. Generally, the components, elements, parts, sections, units, modules, assemblies, processes, and procedures described in the embodiments of this application and shown in the accompanying drawings can be arranged and designed in various different configurations.

[0060] Flowcharts are used in this application to illustrate the operations performed by a "system," "apparatus," "device," and / or "module" according to embodiments of this application. It should be understood that preceding or subsequent operations are not necessarily performed in exact order. Instead, certain steps may be processed in reverse order or simultaneously. Furthermore, other operations may be added to these processes, or one or more operations may be removed from them.

[0061] III. Computer program storage media

[0062] If the functions described in this application are implemented as software functional modules and sold or used as independent products, they can be stored in a computer-readable storage medium, i.e., a software product.

[0063] This application proposes a computer-readable storage medium. The storage medium is used to store a computer program, and when a computer reads the computer program from the storage medium, the computer performs operations corresponding to the watermarking method described in Part One.

[0064] Computer-readable storage media may contain a propagated data signal encoded with a computer program, for example, on baseband or as part of a carrier wave. This propagated signal may take various forms, including electromagnetic, optical, or suitable combinations thereof. The storage medium may be, but is not limited to: floppy disks, optical disks, hard disks, USB flash drives, TF cards (T-Flash Card, also known as MicroSD cards), SD cards (Secure Digital Memory Cards), MMC cards (Multi Media Cards), SM cards (Smart Media Cards), Memory Sticks, XD cards, CF cards (Compact Flash Cards), etc.

[0065] This medium can be connected to an instruction execution system, apparatus, or device to enable communication, propagation, or transmission of a program for use. Program code located on a computer storage medium can be propagated through any suitable medium, including radio, cable, fiber optic cable, RF, or similar media, or any combination of the above media. The computer program code required for the operation of each part of this application can be written in any one or more programming languages, including object-oriented programming languages ​​such as Java, Scala, Smalltalk, Eiffel, JADE, Emerald, C++, C#, VB.NET, Python, etc., conventional procedural programming languages ​​such as C, Visual Basic, Fortran 2003, Perl, COBOL 2002, PHP, ABAP, dynamic programming languages ​​such as Python, Ruby, and Groovy, or other programming languages. This program code can run entirely on the user's computer, or as a standalone software package on the user's computer, or partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the latter case, the remote computer can be connected to the user's computer through any network, such as a local area network (LAN) or wide area network (WAN), or connected to an external computer (e.g., via the Internet), or in a cloud computing environment, or used as a service such as Software as a Service (SaaS).

[0066] The basic concepts have been described above. Obviously, for those skilled in the art, the detailed disclosure above is merely illustrative and does not constitute a limitation of this application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to this application. Such modifications, improvements, and corrections are suggested in this application, and therefore remain within the spirit and scope of the exemplary embodiments of this application.

[0067] Furthermore, this application uses specific terms to describe its embodiments. For example, "one embodiment" or "some embodiments" refers to a particular feature, structure, or characteristic related to at least one embodiment of this application. Therefore, it should be emphasized and noted that "some embodiments" or "one embodiment" mentioned twice or more in different locations in this specification do not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of this application can be appropriately combined.

[0068] As indicated in this application and claims, unless the context clearly indicates otherwise, the terms "a," "first," "second," and / or "the" are not specifically singular in quantity, but rather descriptive terms used for distinction and classification. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of explicitly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0069] The above descriptions are merely various embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A digital watermarking method for urban 3D models, characterized by: The city 3D model includes a terrain grid and a building grid, and the terrain grid has several building area holes that are adapted to the building grid. The watermarking method includes the following steps: Obtain the terrain mesh volume; Obtain a terrain material image with an embedded terrain watermark image from the terrain material library; or, obtain terrain material material from the terrain material library and implicitly embed the terrain watermark image obtained from the watermark database into the terrain material material to generate a watermarked terrain material image. The watermarked terrain material image is embedded into the terrain mesh to generate a watermarked 3D terrain model. Based on the geographic spatial relationship, the corresponding building mesh is embedded in the building area holes of the watermarked 3D terrain model to generate a watermarked 3D city model.

2. The watermarking method according to claim 1, characterized in that: Obtain the building mesh; Obtain a building material image with an embedded building watermark image from the building material library; or, obtain a building material material from the building material library and implicitly embed the building watermark image obtained from the watermark database into the building material material to generate a watermarked building material image. The watermarked building material image is embedded into the building mesh to generate a watermarked 3D building model; Based on the geographic spatial relationship, the corresponding watermarked 3D building model is embedded in the building area hole of the watermarked terrain 3D model to generate a watermarked city 3D model.

3. The watermarking method according to claim 1, characterized in that: The city 3D model also includes several indoor scene models, each of which corresponds to a room in the building grid. The indoor scene model includes window areas, wall areas, and / or floor areas; The indoor scene material image with embedded indoor scene watermark image is obtained from the indoor scene material library, or the indoor scene watermark image obtained from the watermark database is embedded into the indoor scene material material obtained from the indoor scene material library to generate an indoor scene material image with embedded indoor scene watermark image. The interior scene material image is embedded into the window area, wall area and / or floor area to generate an interior scene 3D model containing watermark and material information.

4. The watermarking method according to claim 3, characterized in that: The indoor scene model contains an embedded indoor watermark image in the window area; When a user instructs the user to view a specific room on the 3D building model, the corresponding interior scene model is retrieved, and the corresponding interior scene is displayed on the visual interface. When the indoor scene viewpoint moves to an area containing windows, the corresponding outdoor scene is displayed in the window area based on the viewpoint position of the current indoor scene viewpoint in the city's 3D scene.

5. The watermarking method according to claim 1, characterized in that: The watermarking method also includes a step of semantic segmentation of the terrain grid; The terrain grid is semantically identified by a trained semantic segmentation model, and several terrain regions are segmented. The terrain regions include at least one type of road region, landscape region, water region, farmland region, forest region, and wilderness region. Based on the label type of the terrain region, obtain the corresponding terrain material image with embedded terrain watermark from the terrain material library, or embed the corresponding terrain watermark image obtained from the watermark database into the corresponding terrain material material obtained from the terrain material library to generate a terrain material image with embedded terrain watermark. The watermark database includes at least multiple tag types from road area watermarks, landscape area watermarks, water area watermarks, farmland area watermarks, forest area watermarks, and wilderness area watermarks.

6. The watermarking method according to claim 1, characterized in that: The city 3D model includes a landscape grid, and the terrain grid has several landscape area holes that are adapted to the landscape grid. The watermarking method includes the following steps: Obtain the landscape mesh; Obtain a landscape material image with an embedded landscape watermark image from the landscape material library; or, obtain a landscape material material from the landscape material library and implicitly embed the landscape watermark image obtained from the watermark database into the landscape material material to generate a watermarked landscape material image. The watermarked landscape material image is embedded into the landscape mesh to generate a watermarked 3D landscape model. Based on the geographic spatial relationship, the corresponding landscape 3D model is embedded in the landscape area hole of the watermarked terrain 3D model.

7. The watermarking method according to claim 1, characterized in that: The city 3D model includes a road grid, and the terrain grid has several road area holes that are adapted to the road grid. The watermarking method includes the following steps: Obtain the road grid; Obtain a road material image with an embedded road watermark image from the road material library; or, obtain road material material from the road material library and implicitly embed the road watermark image obtained from the watermark database into the road material material to generate a watermarked road material image. The watermarked road material image is embedded into the road mesh to generate a watermarked 3D road model; Based on the geographic spatial relationship, the corresponding road 3D model is embedded in the road area hole of the watermarked terrain 3D model.

8. The watermarking method according to claim 1, characterized in that: The city 3D model includes a water area grid, and the terrain grid has several water area holes that are adapted to the water area grid. The watermarking method includes the following steps: Obtain the water area grid; Obtain a water texture image with an embedded water texture image from the water texture library; or, obtain water texture material from the water texture library and implicitly embed the water texture image obtained from the watermark database into the water texture material to generate a water texture image with a watermark. The water-marked water texture image is embedded into the water mesh to generate a water-marked 3D model of the water. Based on the geographic spatial relationship, the corresponding water area 3D model is embedded in the water area hole of the water area in the water-marked 3D terrain model.

9. A digital watermarking system for urban 3D models, characterized in that: The watermarking system includes a city 3D model, a watermark embedding module, a material mapping module, a material database, a watermark database, and a compositor; The city 3D model includes a terrain grid and a building grid, and the terrain grid has several building area holes that are adapted to the building grid. The material database includes a terrain material library and building material images; The watermark database includes topographic watermarked images; The watermark embedding module is used to obtain the terrain mesh; obtain a terrain material image with an embedded terrain watermark image from the terrain material library; or, obtain terrain material material from the terrain material library and implicitly embed the terrain watermark image obtained from the watermark database into the terrain material material to generate a watermarked terrain material image. The material mapping module is used to embed the watermarked terrain material image into the terrain mesh to generate a watermarked 3D terrain model. The synthesizer is used to embed the corresponding building mesh into the building area holes of the watermarked 3D terrain model according to the geospatial location relationship, so as to generate a watermarked 3D city model.

10. A computer program storage medium, characterized in that: The storage medium is used to store a computer program. When the computer reads the computer program in the storage medium, the computer runs the digital watermarking method for the three-dimensional urban model as described in any one of claims 1-9.

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