Flight view display method and system based on VTK

Abstract

The invention discloses a flight scene display method and system based on VTK, and belongs to the technical field of flight simulation and avionics display. The method comprises the following steps: reading and converting a digital elevation model, a satellite image and three-dimensional model data through a VTK pipeline, and constructing a three-dimensional terrain and scene; mapping the aircraft pose data into viewpoint parameters, and driving a virtual camera to dynamically render; vTK coloring, texture and marking functions are utilized to superpose a flight path and a navigation mark in real time, and a flight visual picture is generated and output; and a real-time data interface and interaction logic are circularly integrated through the main control, so that continuous rendering and driving are realized. The high-fidelity visual scene generation is realized based on the VTK, the expandability and the configuration flexibility are improved by adopting an open and modular architecture, the dependence on special hardware and a commercial simulation platform is reduced, and an economic and efficient solution is provided for flight simulation and avionics research and development.

Description

Technical Field

[0001] This invention relates to the field of flight simulation and avionics display technology, and more specifically, to a flight visual display method and system based on the VTK visualization tool library. Background Technology

[0002] Flight visualization systems are a core component of flight simulators and avionics system R&D and simulation verification platforms. They provide pilots and researchers with an intuitive and realistic external visual environment and overlay display of flight information. High-quality flight visualization is crucial for improving training effectiveness, conducting ergonomics assessments, and validating navigation algorithms.

[0003] Currently, most mainstream flight visualization solutions rely on specific commercial simulation platforms (such as FlightGear and Prepar3D's visualization modules) or professional visualization software (such as Vega Prime and high-level encapsulations of Open Scene Graph). While these existing solutions are functionally mature, they generally suffer from the following drawbacks: First, their system architecture is relatively closed, with core rendering logic deeply coupled to specific engines, resulting in poor scalability and configurability. Users find it difficult to make in-depth modifications to meet specific needs (such as importing special data formats or achieving customized rendering effects). Second, secondary development is difficult, with a steep learning curve, and commercial licensing agreements limit their application in agile research and customized projects. Finally, these solutions often have a strong dependence on dedicated graphics hardware or specific runtime environments, increasing deployment costs and complexity.

[0004] Therefore, the industry urgently needs a technical solution that is open in architecture, easy to customize, does not depend on a specific commercial platform, and can efficiently generate high-fidelity flight visuals. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a flight visual display method and system based on VTK to solve the problems of closed system architecture, difficulty in secondary development, and dependence on specific platforms and hardware in the existing system.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] On one hand, the present invention provides a flight visual display method based on VTK, comprising the following steps:

[0008] Step S1: 3D Scene Construction: Based on the VTK visualization tool library, read and convert digital elevation model data and satellite remote sensing image data to construct a 3D terrain scene with realistic surface texture. At the same time, load and integrate 3D model data.

[0009] Step S2: Viewpoint Dynamic Driving: Real-time acquisition of the aircraft's pose data, and mapping the pose data to the position and orientation parameters of the virtual camera in the VTK rendering scene to drive synchronous viewpoint updates;

[0010] Step S3 Enhancement Information Overlay: Using VTK's graphics drawing function, preset flight enhancement information is overlaid on the three-dimensional scene in real time to synthesize a flight visual image;

[0011] Step S4 Real-time rendering and display control: By integrating the data interface and interaction logic through the main control loop, steps S1 to S3 are executed in a loop to realize the real-time rendering and display of the flight scene.

[0012] Preferably, in step S1, the specific steps for constructing the 3D scene are as follows:

[0013] Step S11: Select the appropriate reader (such as vtkDEMReader, vtkXMLImageDataReader or GDAL-based reader) according to the DEM data format to import the digital elevation raster, use vtkImageDataGeometryFilter to generate terrain plane geometry, and combine vtkWarpScalar to deform the terrain undulation according to the elevation scalar. If necessary, use vtkTriangleFilter to triangulate the mesh to obtain a triangular patch terrain model.

[0014] Step S12: Read satellite remote sensing images and create vtkTexture. Set texture coordinates according to the spatial range of the image and the terrain (vtkTextureMapToPlane can be used to generate / adjust TCoords) to realize texture mapping of the image to the terrain grid.

[0015] Step S13: Import 3D models of airports, buildings, and aircraft using vtkOBJReader or vtkGLTFReader, and align the scale and coordinates using vtkTransform. Organize and build the complete scene using vtkActor / vtkAssembly or similar methods.

[0016] Preferably, in step S2, the pose data includes the longitude, latitude, altitude, pitch angle, roll angle, and yaw angle of the aircraft; the mapping process includes: converting geographic coordinates into local Cartesian coordinates through coordinate transformation, calculating the view matrix based on the attitude angles, and finally setting the position, focal length, and vertical direction of the vtkCamera.

[0017] Preferably, in step S3, the flight enhancement information includes flight path lines, waypoint markers, runway markings, terrain warning prompts, and two-dimensional flight instrument symbols. A geometric path is created using vtkPolyData, and the flight path line is generated through pipelined rendering using vtkTubeFilter; text or graphic symbols that always face the camera are created using vtkVectorText and vtkFollower; and a two-dimensional instrument panel is drawn in an overlay on the rendering window using vtkContext2D.

[0018] Preferably, in step S4, the method for real-time rendering of the flight scene is as follows: multi-level resolution data layers are constructed for the digital elevation model data and remote sensing image data respectively. During the rendering process, the resolution level required for the current display is determined according to the viewpoint parameters, and the corresponding resolution data layer is simultaneously selected in the digital elevation model data and remote sensing image data for loading and rendering, so as to ensure the display accuracy of near-view details while reducing the data processing and rendering overhead of distant areas.

[0019] Preferably, in step S4, the method for real-time display of the flight scene is as follows: based on the view frustum range of the virtual camera, the camera height, and the preset scene load threshold, the number of terrain units participating in the rendering is dynamically determined, and the loading or unloading control is performed on terrain units that exceed the view frustum range or do not meet the current resolution requirements, so as to maintain the real-time performance and stability of the scene display under complex terrain and high-speed flight conditions.

[0020] On the other hand, the present invention provides a VTK-based flight visual display system, comprising:

[0021] The data preprocessing module is used to read and process geographic information data and 3D models based on VTK to construct a basic 3D scene;

[0022] The viewpoint-driven module is used to calculate and set the position and orientation parameters of the VTK rendering camera based on the aircraft's pose data.

[0023] The visual composition module is used to overlay flight enhancement information graphics onto the basic three-dimensional scene to generate a flight visual image;

[0024] The main rendering module is used to manage data flow, respond to interactive commands, and control the rendering loop to continuously output the flight scene images.

[0025] The system uses VTK as its core graphics rendering engine.

[0026] The beneficial effects of this invention are as follows:

[0027] This invention is built entirely on the open-source VTK library, eliminating dependence on specific commercial simulation platforms. VTK's modular pipeline architecture makes each processing stage of the system (data reading, filtering, mapping, rendering) clearly controllable. Users can easily replace or extend any module as needed, such as supporting new geographic data formats or implementing specific coloring algorithms, greatly improving the system's configurability and secondary development efficiency.

[0028] High-fidelity and efficient rendering: VTK boasts powerful scientific data visualization capabilities and an optimized 3D graphics rendering pipeline, enabling efficient processing of large-scale terrain data and complex models to achieve high-fidelity 3D scene rendering. Utilizing its texture mapping, lighting models, and transparency blending features, it can generate highly realistic flight scenes.

[0029] Cross-platform compatibility and low cost: VTK natively supports cross-platform operation (Windows, Linux, macOS, etc.). This invention adopts a pure software architecture, which reduces the dependence on dedicated graphics hardware or specific operating systems, enabling the solution to be deployed on a wider range of general-purpose computing devices. It provides a flexible and economical solution for flight simulation, teaching and research, and avionics system prototype verification.

[0030] High degree of functional integration: This method integrates terrain rendering, model loading, viewpoint-driven, enhanced information overlay and interactive control into a unified VTK framework, realizing a complete and smooth pipeline from raw data to final visual output, simplifying system complexity and improving development and maintenance efficiency. Attached Figure Description

[0031] Figure 1 Here is a flowchart of a VTK-based flight visual display method;

[0032] Figure 2 This is a structural diagram of a VTK-based flight visual display system;

[0033] Figure 3 This is a rendering of a flight visual display based on VTK. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings. It should be noted that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0035] like Figure 1 As shown, the VTK-based flight visual display method provided by this invention includes the following steps:

[0036] Step S1: 3D Scene Construction: Based on the VTK visualization tool library, read and convert digital elevation model data and satellite remote sensing image data to construct a 3D terrain scene with realistic surface texture. At the same time, load and integrate 3D model data.

[0037] Specifically, in step S1, prepare TIF format DME digital elevation model data, TIF format satellite remote sensing imagery, and OBJ format 3D models of aircraft and airport buildings. The vtkGDALRasterReader raster data reader is used to read the DEM and remote sensing image data respectively, and the vtkOBJReader is used to import the 3D model data. Subsequently, the DEM raster is geometrically processed and its elevation deformed using the VTK visualization pipeline, converting it into a triangular mesh terrain model in vtkPolyData format. Based on this, texture coordinates are generated according to the spatial extent of the remote sensing imagery and terrain data, and vtkTexture and vtkTextureMapToPlane are used to achieve texture mapping from the imagery to the terrain mesh. Finally, the terrain actor and each 3D model actor are added to vtkRenderer to complete the construction of the static 3D scene.

[0038] Step S2: Dynamic viewpoint driving: Real-time acquisition of the aircraft's pose data, and mapping the pose data to the position and orientation parameters of the virtual camera in the VTK rendering scene to drive synchronous viewpoint updates.

[0039] Specifically, in step S2, pose data packets from flight simulation software (such as X-Plane) or a real flight data recorder are received in real time via the UDP protocol to obtain the aircraft's longitude, latitude, altitude, and attitude angles at the current moment. The geodetic coordinates are converted to scene world coordinates, and the camera orientation is calculated based on yaw, pitch, and roll angles. In the rendering loop, methods such as `vtkCamera.SetPosition()`, `SetFocalPoint()`, and `SetViewUp()` are called to update the camera parameters, thereby simulating the view observed from the aircraft cockpit.

[0040] Step S3 Enhancement Information Overlay: Using VTK's graphics drawing function, preset flight enhancement information is overlaid on the three-dimensional scene in real time to synthesize a flight visual image.

[0041] Specifically, in step S3, additional vtkActors are created in the renderer to represent the enhanced information. For example, using the vtkContext2D API, vector graphics of 2D dashboards such as the airspeed indicator and altimeter are drawn at specified screen coordinates in the rendering window. These enhanced elements, together with the 3D terrain, constitute the final flight view, such as... Figure 3 As shown.

[0042] Step S4 Real-time rendering and display control: By integrating the data interface and interaction logic through the main control loop, steps S1 to S3 are executed in a loop to realize the real-time rendering and display of the flight scene.

[0043] Specifically, in step S4, a rendering event loop based on vtkRenderWindowInteractor is created and started. This loop automatically executes callback functions within each frame cycle, with the following sequential logic: reading updated aircraft pose data, driving virtual camera parameter updates based on this data, and triggering a redraw of the rendering window. This framework also listens for and processes user input events, enabling free switching of viewpoints, simulation flow control, and layered display management. Specifically, users can independently control the display and hiding of terrain meshes, flight paths, navigation markers, and various augmentation information layers via keyboard or mouse commands, thus creating a fully interactive real-time simulation environment.

[0044] Specifically, in step S4, to eliminate the computational load of invisible areas, the main control module dynamically constructs the view frustum of the virtual camera in each frame based on the latest state parameters. These parameters include: camera world coordinate position, viewing direction vector, up direction vector, vertical field of view angle, rendering window aspect ratio, and near and far clipping plane distances. The calculated right direction vector determines the six plane equations defining the view frustum space. The scene terrain is pre-divided into regular terrain units. Each unit is associated with a pre-computed axis-aligned bounding box. Before rendering each frame, a view frustum clipping test is performed on each terrain unit: if the axis-aligned bounding box is completely outside any view frustum plane, the unit is determined to be invisible and discarded; otherwise, it is included in the candidate rendering set for this frame. This mechanism ensures that only valid data within the view frustum is processed subsequently.

[0045] Specifically, in step S4, to balance the rendering efficiency of distant terrain with the visual detail of nearby terrain, the system adopts adaptive detail level technology:

[0046] 1) Resolution Level Mapping: Calculate the Euclidean distance from the virtual camera to the center of each candidate terrain unit. The system presets a set of distance thresholds (e.g., near, medium, and far). Based on the distance falling within the specified range, the terrain unit is dynamically mapped to the corresponding resolution level.

[0047] 2) Synchronous Loading of Multi-Resolution Data: For digital elevation models and satellite remote sensing imagery data, the system constructs a multi-level overview pyramid for the dataset during the preprocessing stage. The downsampling scaling levels are: 1, 2, 4, 8, 16, 32, 64, 128, and 256 times the original pixel resolution, respectively. Level 1 represents the original resolution, and the other levels correspond to pixel resolutions that are 2, 4, 8, 16, 32, 64, 128, and 256 times the original pixel resolution. During rendering, the main control module synchronously schedules and loads matching terrain elevation geometric grid data and image texture data for the same terrain unit based on the determined levels, ensuring the consistency of geometric contours and surface textures at different viewing distances.

[0048] Specifically, in step S4, to maintain stable rendering performance, the system performs intelligent load control based on the runtime state:

[0049] 1) Total number of rendering units constraint: The system presets multiple flight altitude ranges and associates them with the range of terrain units that can be rendered in each range (the minimum value is set to 36 and the maximum value is 30,000). When the virtual camera is in the low-altitude range, more units are allowed to be rendered to present rich details; when it is in the high-altitude range, the number is limited to ensure rendering efficiency for large-scale scenes.

[0050] 2) Incremental Loading Rate Limiting: To avoid momentary stuttering caused by a large number of new terrain units being loaded simultaneously in a single frame due to rapid camera movement, the system sets a maximum limit of 5 new units to be loaded per frame. This strategy smoothly distributes the loading pressure across multiple consecutive frames, significantly improving visual continuity and interactive response speed.

[0051] like Figure 2 As shown, in order to realize the above-mentioned VTK-based flight visual display method, this embodiment modularizes the functions of steps S1 to S4 and organizes them into a visual display system in a data stream manner.

[0052] Specifically, the flight visual display system is based on the VTK rendering pipeline and includes a data preprocessing module, a viewpoint-driven module, a visual composition module, and a main control rendering module. The data preprocessing module is responsible for reading, aligning, meshing, and mapping data such as digital elevation models and remote sensing images in step S1 to generate a basic 3D scene. The viewpoint-driven module completes the processing flow in step S2, receiving external pose data (via UDP, User Datagram Protocol, etc.), performing coordinate calculations, and updating virtual camera parameters in real time. The visual composition module implements the processing flow in step S3, overlaying flight enhancement information (such as flight paths, navigation points, warning prompts, and instrument symbols) onto the basic scene and performing composite output. The main control rendering module implements the processing flow in step S4, responsible for main loop scheduling, event interaction, and rendering refresh, and combining view frustum clipping and resolution level scheduling strategies to achieve continuous real-time rendering output, thus completing the closed-loop processing from data input to visual display.

[0053] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this invention, and these modifications or substitutions should all be covered within the scope of protection of this invention. Therefore, the scope of protection of this invention should be determined by the scope of the claims.

Claims

1. A flight visual display method and system based on VTK, characterized in that, Includes the following steps: S1 3D Scene Construction: Based on the VTK visualization tool library, it reads and converts digital elevation model data and satellite remote sensing image data to construct a 3D terrain scene with realistic surface texture. At the same time, it loads and integrates 3D model data. S2 Viewpoint Dynamic Drive: Real-time acquisition of the aircraft's pose data, and mapping the pose data to the position and orientation parameters of the virtual camera in the VTK rendering scene to drive synchronous viewpoint updates; S3 Enhanced Information Overlay: Utilizing VTK's graphics rendering capabilities, preset flight enhancement information is overlaid on the three-dimensional scene in real time to synthesize a flight visual image; S4 Real-time Rendering and Display Control: This involves integrating data interfaces and interaction logic through a main control loop, and cyclically executing steps S1 to S3. The main control loop executes the following during each frame rendering process: a) View frustum clipping and resolution adaptation: The terrain unit is clipped according to the view frustum range of the virtual camera, and the corresponding multi-level resolution is determined for the synchronization of the digital elevation model and satellite remote sensing image data based on the spatial distance between the virtual camera and the terrain unit, and the data of the corresponding resolution is loaded for rendering; b) Dynamic scene management: Based on the camera height and preset scene load threshold, the terrain unit is loaded or unloaded to achieve real-time, smooth rendering and display of the flight scene.

2. The flight visual display method based on VTK according to claim 1, characterized in that, In step S1, the digital elevation model is triangulated using the VTK pipeline, and the satellite remote sensing image is coordinate registered and texture mapped to fit the terrain grid surface, thereby constructing a three-dimensional terrain scene with realistic surface texture.

3. The VTK-based flight visual display method according to claim 1, characterized in that, In step S2, the pose data includes the longitude, latitude, altitude, pitch angle, roll angle, and yaw angle of the aircraft; the mapping process includes converting the pose data into the position coordinates and attitude matrix of the VTK camera in the world coordinate system.

4. The VTK-based flight visual display method according to claim 1, characterized in that, In step S3, the flight enhancement information includes at least one of the following: flight path lines, navigation point markers, runway markings, terrain warning prompts, and flight instrument symbols.

5. The VTK-based flight visual display method according to claim 1, characterized in that, In step S4, both the digital elevation model data and the satellite remote sensing image data are pre-constructed with multi-level resolution data layers; the resolution adaptation process ensures the consistency of terrain geometric details and surface texture details at different viewing distances.

6. The VTK-based flight visual display method according to claim 1, characterized in that, In step S4, the dynamic scene management maintains a balance between rendering performance and visual display quality by balancing the number of terrain units participating in rendering with the system load.

7. A VTK-based flight visual display system, characterized in that, The system for implementing the method as described in any one of claims 1 to 6 comprises: The data preprocessing module is used to read and process geographic information data and 3D models based on VTK to construct a basic 3D scene; The viewpoint-driven module is used to calculate and set the position and orientation parameters of the VTK rendering camera based on the aircraft's pose data. The visual composition module is used to overlay flight enhancement information graphics onto the basic three-dimensional scene to generate a flight visual image; The main rendering module manages the data flow, responds to interactive commands, and controls the rendering loop; during each frame rendering process, the main rendering module executes: a) The terrain units are clipped according to the view frustum of the virtual camera, and the corresponding resolution level is determined and loaded for rendering based on the spatial distance between the virtual camera and the terrain units and the digital elevation model and satellite remote sensing image data. b) Based on the flight altitude and the preset scene load threshold, dynamically manage the loading and unloading of terrain units to continuously output the flight scene images that are updated in real time.

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