CN107369205B - A mobile terminal city 2D and 3D linkage display method - Google Patents

Abstract

The invention discloses a method for displaying two-dimensional and three-dimensional linkage of a city on a mobile terminal, comprising the following steps: 1. Analyzing and organizing three-dimensional file data, establishing a three-dimensional scene, and displaying a three-dimensional view; 2. Obtaining a current perspective point and a direction point in the three-dimensional scene , and transmit it to the two-dimensional view in real time; 3. The two-dimensional view analyzes the two-dimensional vector data, and draws the two-dimensional view in real time by combining the projection values of the current perspective point and the direction point in the three-dimensional scene on the horizontal plane. This method can realize the linkage display of 2D and 3D, give full play to the advantages of 2D map in location positioning, and realize complementary advantages. While browsing the 3D urban scene, the current perspective positioning and observation direction can be seen on the 2D scene.

Description

A mobile terminal city 2D and 3D linkage display method

technical field

The invention belongs to the field of virtual reality, and in particular relates to a method for performing 2D and 3D linked display on a mobile terminal.

Background technique

In recent years, although the continuous development of mobile 3D GIS has further improved the expression level of geographic information, it is still in the development stage, and it is more appropriate to start with mature 2D GIS to solve some problems. This requires the realization of 2D and 3D integration, giving full play to the respective advantages of 2D GIS and 3D GIS. At the same time, with the introduction of concepts such as "smart city" and "digital earth", the research on 3D city visualization technology on mobile terminals is particularly important.

The principle of linkage between the two-dimensional display window and the three-dimensional display window is realized through a certain message response mechanism. Realizing the one-to-one mapping of two-dimensional map coordinates and three-dimensional scene coordinates is the basic premise of the response, and the projected reference coordinate system of the two-dimensional electronic map should be consistent with the coordinate system of the three-dimensional scene construction. The system realizes the synchronization of 2D and 3D window display through the mutual transmission of 2D and 3D coordinates. In order to fully reflect the respective advantages of 2D GIS and 3D GIS, some related technical requirements need to be fully considered in the research process of realizing GIS 2D and 3D linkage display. The main requirements are listed as follows:

(1) Data requirements

The data model design, data organization and storage in the 2D and 3D linkage display must fully consider the characteristics of 2D and 3D, and it is best to share a set of geospatial data with the source data. In some display situations, at least two-dimensional data and three-dimensional data must be required to be related, and the corresponding proportions must be consistent.

(2) Display control requirements

The same rules and the same human-computer interaction modules should be used in the visualization and manipulation of 2D and 3D scenes, and the consistency of scene scope and scene manipulation in 2D and 3D display environments should be maintained. The operation of the scene includes forward, backward, rotation, zoom in, zoom out, etc. When the visualization operation is performed, the perspective, content, and scope of the scene change, and the indicators of the other window also change accordingly.

Of course, there are still many contents that need to be consistent in the process of 2D and 3D linkage. However, due to the relatively limited capabilities of the mobile terminal platform, too much consideration of consistent content will inevitably lead to the smoothness of real-time interaction, and should focus on application characteristics. necessary linkage requirements. At present, the main problems of the existing technologies for realizing 2D and 3D linkage are: 1. The realization platform is mainly based on the desktop terminal, and the mobile terminal is relatively small; 2. Most of the 2D and 3D linkage display software is developed with the help of third-party platforms, relying on It is highly flexible, the implementation process is not transparent, and the data organization is not clear.

SUMMARY OF THE INVENTION

Purpose of the invention: In view of the problems existing in the prior art, the present invention provides a mobile terminal city 2D and 3D linkage display method, which can realize 2D and 3D linkage display on the mobile terminal, aiming at "high-rise buildings, covering the sky and sun" Based on the characteristics of urban scenes, the advantages of two-dimensional maps in location positioning are used to achieve complementary advantages. While browsing three-dimensional urban scenes, you can see the positioning and observation direction of the current perspective on the two-dimensional scene.

Technical scheme: The present invention adopts the following technical scheme: a method for displaying two-dimensional and three-dimensional linkage of a mobile terminal city, comprising the following steps:

(1) Analyze and organize 3D file data, build 3D scenes, and display 3D views;

(2) Obtain the current perspective point and direction point in the 3D scene, and transfer it to the 2D view in real time;

(3) The two-dimensional view analyzes the two-dimensional vector data; combines the projection position of the current viewpoint point and the direction point in the three-dimensional scene on the horizontal plane, and draws the two-dimensional view in real time.

The three-dimensional file data includes three-dimensional coordinate data, and the projection value of the three-dimensional coordinate data on the horizontal plane is in a corresponding proportional relationship with the two-dimensional vector data.

The 3D file data is obtained from the GIS 2D vector map; add the height attribute in ArcGIS, and use the SketchUp plug-in to stretch it into a 3D model file, open it in SketchUp for model editing, add textures, and export a 3D universal obj format file as a 3D model file. file data.

In the present invention, step (1) adopts OpenGL ES to establish a three-dimensional scene and display a three-dimensional view. Step (2) specifically includes the following steps:

(2.1) According to the parameters of the projection view cone and the camera parameters set by OpenGL ES, select the lower bound center point of the near plane as the transmitted perspective point, and select the direction point of the camera as the transmitted direction point;

(2.2) using the inverse matrix of the scene transformation matrix to calculate the untransformed three-dimensional position coordinates corresponding to the current point of view and the direction point;

(2.3) The projection value of the three-dimensional original position coordinates calculated in step (2.2) on the horizontal plane is passed to the two-dimensional view.

The display of the 3D view and the display of the 2D view are completed by different threads; step (2) realizes inter-thread communication through a singleton class, and transmits the current viewpoint point and direction point in the acquired 3D scene to the 2D view display thread in real time.

The above mobile terminal is a mobile embedded device based on an Android system or an IOS system.

Beneficial effects: Compared with the prior art, the mobile terminal city 2D and 3D linkage display method disclosed in the present invention has the following advantages: 1. Two-dimensional and 3D linkage display can give full play to the advantages of the two-dimensional map in location positioning, and realize complementary advantages. While browsing the 3D city scene, you can see the positioning and viewing direction of the current perspective on the 2D scene; 2. On the 2D vector map, you can mark the position and perspective direction of the current city 3D scene roaming process in real time.

Description of drawings

Fig. 1 is a block diagram of a mobile terminal city two-dimensional scene linkage display;

Fig. 2 is the flow chart of 2D and 3D scene linkage realization;

Fig. 3 is a two-dimensional three-dimensional linkage display effect diagram of a mobile terminal;

Fig. 4 is the flow chart of realizing 3D city model based on 2D vector map and 3D modeling software;

FIG. 5 is a schematic diagram of a transmitted perspective point;

6 is a schematic diagram of the scaling of three-dimensional original coordinates and two-dimensional vector coordinates;

Detailed ways

The invention discloses a mobile terminal city two-dimensional linkage display method, comprising the following steps:

(1) Analyze and organize 3D file data, build 3D scenes, and display 3D views;

(2) Obtain the current perspective point and direction point in the 3D scene, and transfer it to the 2D view in real time;

(3) The two-dimensional view analyzes the two-dimensional vector data; combines the projection position of the current viewpoint point and the direction point in the three-dimensional scene on the horizontal plane, and draws the two-dimensional view in real time.

This embodiment further illustrates the present invention by constructing a 2D and 3D linkage display interface on the mobile terminal. As shown in Figure 1, a 3D view display thread and a 2D view display thread are established on the mobile terminal, and then the initialization of the 2D window and the 3D window is performed respectively, and the 2D SHP data and the 3D obj data are also analyzed respectively. Organized into system memory. After the initialization work is completed, it will enter the real-time refresh drawing stage. Under normal circumstances, two-dimensional data is used for real-time rendering of a two-dimensional window, and three-dimensional data is used for real-time rendering of a three-dimensional window without interfering with each other. In the 2D and 3D linkage of the scene, every time the 3D view thread draws the corresponding scene, it needs to solve the perspective and transfer it to the 2D real-time rendering thread, and the 2D view will draw the current perspective point in real time. Realize the scene linkage between them. In this embodiment, the communication between threads is implemented through a singleton class, and the acquired current perspective point and direction point in the 3D scene are transmitted to the 2D view display thread in real time.

The present invention uses OpenGL ES to establish a three-dimensional scene and display a three-dimensional view. OpenGL ES is a subset of OpenGL 3D graphics API. It is specially designed for embedded devices such as mobile phones, PDAs and game consoles. Building 3D scenes based on OpenGL ES is also an effective method for 3D development on mobile devices, and it also gives full play to mobile devices. Flexible and convenient features.

Obtain the current perspective point and direction point in the 3D scene and transfer it to the 2D view in real time. The specific steps are:

(2.1) According to the parameters of the projection view cone and the camera parameters set by OpenGL ES, select the lower bound center point of the near plane as the transmitted perspective point, and select the direction point of the camera as the transmitted direction point;

(2.2) using the inverse matrix of the scene transformation matrix to calculate the untransformed three-dimensional position coordinates corresponding to the current point of view and the direction point;

(2.3) The projection value of the three-dimensional original position coordinates calculated in step (2.2) on the horizontal plane is passed to the two-dimensional view.

The two-dimensional view draws a two-dimensional view according to the two-dimensional vector data, the projection value of the current viewpoint point and the direction point in the three-dimensional scene on the horizontal plane, as shown in Figure 2.

As shown in FIG. 3 , the effect diagram of the urban 2D and 3D linkage display effect of the mobile terminal implemented in this embodiment, the right picture is a real-time 3D scene, the left picture is a real-time 2D scene, and the current 2D scene is marked by a dot in the 2D scene. The three-dimensional view point, the arrow marks the current viewing direction of the view point.

As shown in Figure 4, the three-dimensional data file used in this embodiment can be a commonly used three-dimensional data format - obj file; the XOZ plane of the coordinate data in the file, that is, the projection of the horizontal plane and the two-dimensional vector data must have a corresponding proportional relationship . This embodiment combines the GIS two-dimensional vector map and the three-dimensional modeling software to realize the establishment of the three-dimensional city model. Add the height attribute in ArcGIS, and use the Sketch Up plug-in to stretch it into a 3D model file, open it in Sketch Up for model editing, add textures, and export a 3D universal obj format file.

As shown in FIG. 5 , in order to fit the actual situation, this embodiment selects and calculates the lower bound center point of the near plane as the transmitted perspective point. In Figure 5, 1 is the observation direction, 2 is the camera viewpoint, 3 is the near plane, 4 is the far plane, 5 is the projection of the direction point on the near plane, and 6 is the lower bound center point of the near plane.

Because the 3D view finally displays the projection of the scene inside the cone on the near plane 3, if the position of the camera is used as the transmitted perspective point, then the perspective point displayed in the 2D view must be behind the current 3D view. big error. This embodiment adopts such a selection principle, which is also very consistent with the visual principle of the interactor, and also avoids certain errors.

As shown in FIG. 6 , in this embodiment, the three-dimensional original coordinates are on the XOZ plane, that is, the projection of the horizontal plane and the two-dimensional vector coordinates satisfy the corresponding relationship, that is, the minimum envelope rectangle of the horizontal projection of the three-dimensional scene and the minimum envelope rectangle of the two-dimensional scene There is a certain proportional relationship between them. In this embodiment, after the position in the original coordinate system of the 3D scene is obtained, the distances ΔX and ΔZ from the position to the left and lower sides of the minimum envelope rectangle projected by the 3D scene on the horizontal plane are calculated, and scaled to form ΔX and ΔZ. X' and △Y"; △X' and △Y' are the distances from the left and bottom of the minimum envelope rectangle of the two-dimensional vector diagram; from this, it can be concluded that the perspective point and direction point in the three-dimensional scene are in the two-dimensional vector The corresponding location coordinates in the map.

Claims (5)

1. a mobile terminal city two-dimensional linkage display method, is characterized in that, comprises the steps: (1) Analyze and organize 3D file data, build 3D scenes, and display 3D views; (2) Obtain the current perspective point and direction point in the 3D scene, and transfer it to the 2D view in real time; (3) The two-dimensional view analyzes the two-dimensional vector data; combines the projection position of the current perspective point and the direction point in the three-dimensional scene on the horizontal plane, and draws the two-dimensional view in real time; In step (1), OpenGL ES is used to establish a three-dimensional scene, and a three-dimensional view is displayed; step (2) specifically includes the following steps: (2.1) According to the parameters of the projection view cone and the camera parameters set by OpenGL ES, select the lower bound center point of the near plane as the transmitted perspective point, and select the direction point of the camera as the transmitted direction point; (2.2) using the inverse matrix of the scene transformation matrix to calculate the untransformed three-dimensional position coordinates corresponding to the current point of view and the direction point; (2.3) The projection value of the three-dimensional original position coordinates calculated in step (2.2) on the horizontal plane is passed to the two-dimensional view. 2. The urban 2D and 3D linkage display method for a mobile terminal according to claim 1, wherein the 3D file data comprises 3D coordinate data, and the projection value of the 3D coordinate data on the horizontal plane is in a corresponding proportional relationship with the 2D vector data . 3. mobile terminal city two-dimensional linkage display method according to claim 1, is characterized in that, described three-dimensional file data is obtained by GIS two-dimensional vector map; In ArcGIS, add height attribute, and utilize Sketch Up plug-in to stretch as. 3D model files, open in Sketch Up for model editing, add textures, and export 3D universal obj format files as 3D file data. 4. mobile terminal city two-dimensional linkage display method according to claim 1 is characterized in that, the display of three-dimensional view and the display of two-dimensional view are completed by different threads; Step (2) realizes inter-thread communication by singleton class, Pass the acquired current viewpoint point and direction point in the 3D scene to the 2D view display thread in real time. 5 . The urban 2D and 3D linkage display method for a mobile terminal according to claim 1 , wherein the mobile terminal is a mobile embedded device based on an Android system or an IOS system. 6 .

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