CN103324783B - Based on the LOD model Real-time Generation of edge contraction - Google Patents

Abstract

The invention discloses a real-time generation method of an LOD model based on edge folding, comprising the following steps: calculating the distance from the viewpoint to the three-dimensional equipment model according to the position of the viewpoint and the position of the three-dimensional equipment model; determining the distance of the three-dimensional equipment model according to the distance from the viewpoint to the three-dimensional equipment model Simplification degree: According to the simplification degree of the 3D device model, the 3D device model is simplified in real time according to the real-time simplification operation based on the vertex simplification weight. Through the real-time simplification of the three-dimensional equipment model, the present invention can obtain an approximate three-dimensional equipment model with the required resolution in real time, and ensure the continuity of the resolution change; by introducing simplified weight values, the visual information of the three-dimensional equipment model can be obtained relatively good reservation.

Description

Real-time generation method of LOD model based on edge folding

technical field

The invention relates to a method for generating a three-dimensional model, in particular to a method for generating a real-time LOD (Levels of Detail) model based on edge folding, and belongs to the technical field of power system simulation.

Background technique

With the continuous development of 3D modeling technology, it is becoming a trend to apply 3D virtual reality technology to power system simulation. Currently, geometric models are becoming more and more detailed to achieve visual realism. However, the substation scene of the power system has the characteristics of a very large number and types of equipment. If highly detailed geometric models are fully adopted, these geometric models are superimposed and displayed in the virtual scene with a large amount of vector data, which will give the data reading of the 3D virtual scene Acquisition, rendering, and drawing have brought enormous pressure, which far exceeds the computing power that the computer graphics card can provide, which makes it difficult for the simulation system to achieve fast rendering of 3D virtual scenes, and significantly reduces the experience of using the simulation system.

To solve the above problems, an effective way is to dynamically load and draw complex 3D vector data in real time. However, there is a shortcoming in the existing methods, that is, they generally require the entire vector data to be loaded into the memory for drawing at the same time, and then display the texture on the terrain, which will inevitably cause a large amount of memory space occupation and computing resources in the simulation system. consume. Due to the limited memory capacity of the computer, when large-scale 3D scenes need to be superimposed for vector data display, the existing vector data display superimposition method is almost inadvisable.

In order to enable the simulation system to quickly draw a large number of 3D models of power equipment and at the same time provide a strong sense of graphic reality, the currently widely used model optimization technology is the level of detail graphics rendering (LOD) technology. LOD technology refers to determining the resource allocation of object rendering according to the position and importance of the nodes of the object model in the display environment, reducing the number of faces and details of non-important objects, so as to obtain high-efficiency rendering operations. In the equipment model modeling stage, LOD technology builds a fixed number of models through modeling software. When the observer is far away from the equipment model, he only needs to see the approximate outline of the equipment model. At this time, the original fine equipment The model is highly simplified to form a rough grid to represent the device model; when the observer is getting closer to the device model, the detailed information of the device model is gradually and continuously added to the original rough grid in real time Up until all the information of the original fine device model is restored. However, in order to ensure the effect of hierarchical details, the transition between models has a certain continuity, often requiring a lot of layers, which will generate a large amount of data, which is difficult to store and transmit effectively.

Contents of the invention

Aiming at the deficiencies in the prior art, the technical problem to be solved by the present invention is to provide a real-time generation method of an LOD model based on edge folding. Through the real-time simplification of the three-dimensional equipment model, the method can obtain an approximate three-dimensional equipment model with required resolution in real time, and can better preserve the visual information of the three-dimensional equipment model.

For realizing above-mentioned purpose of the invention, the present invention adopts following technical scheme:

A real-time generation method of an LOD model based on edge folding, comprising the following steps:

Calculate the distance from the viewpoint to the 3D device model according to the position of the viewpoint and the position of the 3D device model;

Determine the degree of simplification of the 3D equipment model according to the distance from the viewpoint to the 3D equipment model;

According to the degree of simplification of the 3D device model, the 3D device model is simplified in real time according to the real-time simplification operation based on the vertex simplification weight.

Preferably, the step of calculating the distance from the viewpoint to the 3D device model according to the position of the viewpoint and the position of the 3D device model further includes:

Determine the three-dimensional coordinates of the viewpoint position according to the current observation position;

Traverse the three-dimensional coordinates of all vertices of the three-dimensional equipment model, and find out the maximum and minimum three-dimensional coordinates of the vertices of the three-dimensional equipment model;

Calculate the three-dimensional coordinates of the center point of the three-dimensional equipment model according to the maximum and minimum values of the three-dimensional coordinates of the vertices of the three-dimensional equipment model;

Calculate the distance from the viewpoint to the device according to the three-dimensional coordinates of the viewpoint position and the three-dimensional coordinates of the center point of the three-dimensional device model.

Preferably, the degree of simplification of the 3D equipment model is configured according to the distance from the viewpoint to the 3D equipment model according to user requirements.

Preferably, the real-time simplification operation based on the vertex simplification weight further includes:

Determine the simplified weight value of the vertex distance of each vertex of the 3D device model according to the position of the viewpoint and the position of each vertex of the 3D device model;

Determine the vertex orientation simplified weight value of each vertex of the 3D equipment model according to the viewpoint orientation and the orientation of each vertex of the 3D equipment model;

Synthesizing the vertex distance simplification weight value and vertex orientation simplification weight value of each vertex of the three-dimensional equipment model to obtain each vertex simplification weight value;

The 3D device model is simplified in real time according to the real-time simplification operation of the 3D device model based on vertex merging according to the simplification weight value.

Preferably, the step of determining the simplified weight value of the vertex distance of each vertex of the three-dimensional equipment model further includes:

Calculate the distance between the viewpoint and each vertex of the 3D device model according to the 3D coordinates of the viewpoint position and the 3D coordinates of each vertex of the 3D device model;

Determine the vertex distance simplification weight value of each vertex of the 3D device model according to the user's requirement according to the distance between the viewpoint and each vertex of the 3D device model.

Preferably, the step of determining the simplified weight value of the vertex orientation of each vertex of the 3D equipment model according to the viewpoint orientation and the orientation of each vertex of the 3D equipment model further includes:

According to the angle between the position of the viewpoint and the positive direction of the Z axis, the angle of the viewpoint is determined;

Determine the vertex orientation angle according to the angle between the vertex position and the positive direction of the Z axis;

According to the user's needs, the simplified weight value of the orientation of the fixed point is determined according to the difference between the orientation angle of the viewpoint and the orientation angle of the vertex.

Preferably, the vertex simplified weight value is calculated according to the following formula:

Simplified weight value of vertex distance × 0.5 + simplified weight value of vertex orientation × 0.5 = simplified weight value of vertex

Preferably, the step of simplifying the 3D equipment model in real time according to the vertex simplification weight value according to the real-time simplification operation of the 3D equipment model based on vertex merging further includes:

Traverse the vertex simplified weight values of all vertices of the 3D device model, and find out the two vertices whose sum of the simplified weights of two adjacent vertices is the smallest;

Remove the triangle whose vertices are the two vertices whose sum of the simplified weights of two adjacent vertices is the smallest at the same time;

If the sum of the simplified weights of two adjacent vertices is the same, remove any one of the vertices as the triangle of the vertices, replace the other with one of the vertices, and remove the replaced vertices;

If the two vertex simplification weight values with the smallest sum of adjacent two vertex simplification weights are not equal, remove the triangle with the vertex with the smallest vertex simplification weight value as the vertex, and replace the vertex simplification with the vertex with the second smallest vertex simplification weight value The vertex with the smallest weight value, remove the vertex to simplify the vertex with the smallest weight value;

Repeat the above steps until the degree of model simplification required by the user is met.

In the real-time generation method of the LOD model provided by the present invention, through the real-time simplification of the three-dimensional equipment model, an approximate three-dimensional equipment model with the required resolution can be obtained in real time, and the continuity of the resolution change can be guaranteed. By introducing simplified weight values, the visual information of the 3D equipment model is better preserved.

Description of drawings

FIG. 1 is a schematic diagram of the operation of vertex merging in the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

In the existing substation simulation system, the substation is modeled by commercial modeling tools (such as 3D modeling software 3DSMax, etc.), and the 3D equipment scene of the substation is generated. The 3D equipment model is the basic unit for constructing the 3D equipment scene of the substation, and the combination of multiple 3D equipment models constitutes the 3D equipment scene model of the substation. In order to further improve the authenticity of the simulation equipment and achieve a more realistic visual effect, a viewpoint is also set in the existing substation simulation system, and users can browse the 3D equipment scene model in the substation simulation system according to the viewpoint position. When the user browses the 3D equipment model in the substation simulation system, the position of the viewpoint also changes correspondingly with the change of the browsing position. The geometric information data of the 3D device model is composed of a set of 3D coordinates of geometric vertices, and these vertices form a triangle every three vertices in order. The spatial position reference point and reference coordinate axis of the viewpoint are consistent with the spatial position reference point and reference coordinate axis of the 3D equipment model in the substation 3D equipment scene.

In the real-time generation method of the LOD model, the following steps are included: calculating the distance from the viewpoint to the 3D device model according to the position of the viewpoint and the position of the 3D device model; determining the degree of simplification of the 3D device model according to the distance from the viewpoint to the 3D device model; The degree of simplification is based on the real-time simplification operation based on the vertex simplification weight to simplify the 3D device model in real time. When using the method provided by the present invention to simplify the 3D equipment model, the farther the 3D equipment model is from the viewpoint, the higher the degree of real-time simplification; the side of the 3D equipment model facing the viewpoint adopts a lower degree of model simplification, and the 3D equipment model faces away from the viewpoint One side adopts a higher degree of model simplification. The following is a detailed description of the real-time generation method of the LOD model based on edge folding provided by the present invention.

Firstly, the steps of calculating the distance from the viewpoint to the 3D device model according to the position of the viewpoint and the position of the 3D device model are introduced.

In one embodiment of the present invention, the step of calculating the distance from the viewpoint to the 3D equipment model mainly includes: determining the 3D coordinates of the viewpoint position according to the current observation position; value and minimum value; calculate the three-dimensional coordinates of the center point of the three-dimensional equipment model according to the maximum and minimum values of the three-dimensional coordinates of the vertices of the three-dimensional equipment model; calculate the distance from the viewpoint to the three-dimensional equipment model according to the three-dimensional coordinates of the viewpoint position and the three-dimensional coordinates of the central point of the three-dimensional equipment model. Details are given below.

Determine the three-dimensional coordinates of the viewpoint position according to the current observation position. In the existing substation simulation system, the position of the general viewpoint is based on the three-dimensional or accurate position of the x, y, and z axes of the current observation position. A 3D device model often has multiple vertices, and the connecting lines between the vertices constitute the outline of the 3D device model. Each vertex has corresponding 3D coordinates. Traverse the 3D coordinates of all vertices of the 3D device model, and find the maximum and minimum values of the 3D coordinates of the vertices of the 3D device model (ie Xmin, Xmax, Ymin, Ymax, Zmin, Zmax). Calculate the coordinates of the central point of the three-dimensional equipment model according to the maximum and minimum values of the three-dimensional coordinates of the vertices of the three-dimensional equipment model; calculate the three-dimensional coordinates of the central point of the three-dimensional equipment model as ((Xmin+Xmax)/2, (Ymin+Ymax)/2, (Zmin+ Zmax)/2). Calculate the distance from the viewpoint to the device according to the three-dimensional coordinates of the viewpoint position and the three-dimensional coordinates of the center point of the three-dimensional device model.

Secondly, the steps of determining the simplification degree of the 3D equipment model according to the distance from the viewpoint to the 3D equipment model are introduced.

When the method provided by the invention is used to simplify the three-dimensional equipment model, the degree of simplification of the three-dimensional equipment model is flexibly configured according to the distance from the viewpoint to the three-dimensional equipment model according to user requirements. In order to maintain the visual effect of the 3D equipment model in the 3D equipment scene of the substation as much as possible, and at the same time simplify the pictures of the 3D equipment model in real time to achieve rapid drawing, it is necessary to use the current viewpoint position in the substation simulation system to map the 3D equipment at different spatial positions. , 3D equipment models with different orientations adopt different degrees of model simplification. The greater the distance from the viewpoint to the 3D device model, the greater the degree of simplification of the 3D model, that is, the greater the proportion of the number of simplified 3D vertices. When the degree of simplification is greater, the hardware resources required for rendering the model are smaller, thereby improving rendering efficiency.

The relationship between the distance from the viewpoint to the 3D device model and the degree of simplification of the 3D device model can be flexibly configured according to different application environments. In one embodiment of the present invention, the number of vertices of the three-dimensional device model is simplified by using the corresponding relationship shown in Table 1. If the distance from the viewpoint to the 3D equipment model is 0 to 10 meters, the number of vertices of the 3D equipment model is not simplified, and all vertices are kept; if the distance from the viewpoint to the 3D equipment model is 10 to 50 meters, the 3D equipment model The number of vertices of the 3D equipment model is simplified to 80% of the original number of vertices; if the distance from the viewpoint to the 3D equipment model is 50-100 meters, the number of vertices of the 3D equipment model is simplified to 70% of the original number of vertices; When the distance of the 3D equipment model is 100-150 meters, the number of vertices of the 3D equipment model is simplified to 60% of the original number of vertices; if the distance from the viewpoint to the 3D equipment model is 150-200 meters, the The number of vertices is simplified to 50% of the original number of vertices; if the distance from the viewpoint to the 3D equipment model is greater than 200 meters, the number of vertices of the 3D equipment model is simplified to 40% of the original number of vertices.

Distance size interval (/m) corresponding degree of simplification 0～10 The number of vertices is not simplified, 100% is reserved 10～50 The number of vertices is simplified to 80% of the original 50～100 The number of vertices is reduced to 70% of the original 100～150 The number of vertices is simplified to 60% of the original 150～200 The number of vertices is reduced to 50% of the original >200 The number of vertices is reduced to 40% of the original

Table 1 Simplification of the distance interval and the number of vertices

Finally, it introduces the steps of real-time simplification of the 3D equipment model according to the simplification degree of the 3D equipment model according to the real-time simplification operation based on the vertex simplification weight.

In one embodiment of the present invention, the step of simplifying the 3D equipment model in real time according to the simplification degree of the 3D equipment model according to the real-time simplification operation based on the vertex simplification weight further includes: determining the 3D equipment according to the position of the viewpoint and the position of each vertex of the 3D equipment model The vertex distance simplified weight value of each vertex of the model; the simplified weight value of the vertex orientation of each vertex of the 3D equipment model is determined according to the orientation of the viewpoint and the orientation of each vertex of the 3D equipment model; the simplified weight of the vertex distance of each vertex of the integrated 3D equipment model The simplified weight value of each vertex is obtained according to the simplified weight value and the simplified weight value of the vertex; the 3D equipment model is simplified in real time according to the real-time simplified operation of the 3D equipment model based on vertex merging according to the simplified weight value. By introducing the simplified weight value, the key graphic information of the 3D equipment model can be preserved. After the 3D equipment model is simplified, the 3D equipment scene of the substation can be drawn more smoothly in real time, and the picture quality is good, so that the visual information of the 3D equipment model can be obtained. A better reservation.

The vertex distance simplified weight value of each vertex of the 3D device model is determined according to the position of the viewpoint and the position of each vertex of the 3D device model. The distance from the viewpoint to the 3D device model and the degree of simplification of the vertices of the 3D device model can be flexibly configured according to different application environments. In an embodiment of the present invention, according to the three-dimensional coordinates of the viewpoint position and the three-dimensional coordinates of each vertex of the three-dimensional device model, the distance between the viewpoint position and each vertex of the three-dimensional device model is calculated first. Then, according to the distance between the viewpoint position and each vertex of the 3D device model, the vertex distance simplified weight value of each vertex of the 3D device model is determined. The calculation method of the simplified weight value of the vertex distance is specifically: by comparing the distance between the viewpoint position and the vertex of the three-dimensional device model with each distance interval in Table 1 in turn. The degree of simplification corresponding to the range of the distance between the viewpoint position and each vertex of the 3D device model. The vertex on the side of the 3D device model facing the viewpoint is closer to the viewpoint, and the vertex on the side facing away from the viewpoint is farther away from the viewpoint. The side of the 3D equipment model facing the viewpoint adopts a lower degree of model simplification, and the side of the 3D equipment model facing away from the viewpoint adopts a higher degree of model simplification. For example, when the distance from the viewpoint to a vertex of the 3D equipment model is 50 to 100 meters, 70% is the simplified weight value of the vertex distance. The simplified weight value of the vertex distance of each vertex of the three-dimensional equipment model is determined according to the above-mentioned method for other distance ranges, and details will not be repeated here.

The vertex orientation simplified weight value of each vertex of the 3D equipment model is determined according to the viewpoint orientation and the orientation of each vertex of the 3D equipment model. The viewpoint orientation is the angle between the viewpoint position of the observer in the substation simulation system and the positive direction of the Z axis, and the orientation of each vertex of the 3D equipment model is the angle between the direction of each vertex and the positive direction of the Z axis. In one embodiment of the present invention, when determining the simplified weight value of the vertex orientation of each vertex of the three-dimensional equipment model, first calculate the angle between the viewpoint and the positive direction of the Z-axis of the substation simulation system (ie, the angle between the viewpoint orientation) according to the current viewpoint position; Then calculate the angle between each vertex of the 3D equipment model and the positive direction of the Z axis of the substation simulation system (the orientation angle of each vertex of the 3D equipment model) according to the 3D coordinates of the vertex of the 3D equipment model; The difference between the orientation angles of each vertex of the model. The vertex orientation simplified weight value of each vertex of the three-dimensional device model is determined according to the difference. When using the method provided by the present invention to simplify the three-dimensional equipment model, the degree of simplification of the three-dimensional equipment model can be flexibly configured according to different application environments according to the difference between the orientation angle of the viewpoint and the orientation angle of each vertex of the three-dimensional equipment model.

In one embodiment of the present invention, the corresponding relationship shown in Table 2 is used to determine the vertex orientation simplified weight value of each vertex of the three-dimensional device model. The method for determining the simplified weight value of the vertex orientation is as follows: by comparing the difference between the orientation angle of the viewpoint and the orientation angle of each vertex of the 3D device model with the distance intervals in Table 2 in turn. The degree of simplification corresponding to the interval of the difference between the orientation angle of the viewpoint and the orientation angle of each vertex of the 3D device model. If the difference between the angle between the viewpoint orientation and the orientation angle of each vertex of the 3D device model is 0 to 10 degrees, the number of vertices of the 3D device model will not be simplified, and 100% will be reserved; if the angle between the viewpoint orientation and the 3D device model When the difference between the orientation angles of each vertex of the model is 10 to 45 degrees, the number of vertices of the 3D equipment model is simplified to 80% of the original number of vertices; When the difference between the orientation angles of the three-dimensional equipment model is 45 to 90 degrees, the number of vertices of the 3D equipment model is simplified to 60% of the original number of vertices; When the difference is 90 to 135 degrees, the number of vertices of the 3D equipment model is simplified to 40% of the original number of vertices; if the difference between the orientation angle of the viewpoint and the orientation angle of each vertex of the 3D equipment model is 135～ At 180 degrees, the number of vertices of the 3D equipment model is simplified to 20% of the original number of vertices.

The difference interval of the orientation angle (/degree) corresponding degree of simplification 0～10 The number of vertices is not simplified, 100% is reserved 10～45 The number of vertices is simplified to 80% of the original 45～90 The number of vertices is simplified to 60% of the original 90～135 The number of vertices is reduced to 40% of the original 135～180 The number of vertices is reduced to 20% of the original

Table 2 The difference interval of the orientation angle and the simplification degree of the number of vertices

The simplified weight value of each vertex is obtained by synthesizing the simplified weight value of the vertex distance and the simplified weight value of the vertex orientation of each vertex of the three-dimensional device model. In one embodiment of the present invention, the simplified weight value of each vertex can be calculated as follows: simplified weight value of vertex distance×0.5+simplified weight value of vertex direction×0.5=simplified weight value of vertex.

In one embodiment of the present invention, the step of simplifying the 3D equipment model in real time according to the vertex simplification weight value according to the real-time simplification operation of the 3D equipment model based on vertex merging further includes the following steps: traversing the vertex simplification weight values of all vertices of the 3D equipment model, Find the two vertices with the smallest sum of the simplified weights of two adjacent vertices; remove the triangle whose vertices are the two vertices with the smallest sum of the simplified weights of the adjacent two vertices; if the sum of the simplified weights of two adjacent vertices The smallest two vertex simplification weight values are equal, then remove any vertex as the triangle of the vertex, replace the other vertex with one vertex, and remove the substituted vertex; if the sum of the simplified weights of two adjacent vertices is the smallest If two vertex simplification weight values are not equal, remove the triangle with the vertex with the smallest vertex simplification weight value as the vertex, replace the vertex with the smallest vertex simplification weight value with the vertex with the second smallest vertex simplification weight value, and remove the vertex simplification weight value The smallest vertices; repeat the above steps until the degree of model simplification that meets the user's needs.

All two adjacent vertices in the 3D device model are traversed to obtain the vertex with the smallest simplified weight value of the two vertices. The real-time simplification method of the three-dimensional equipment model using vertex merging performs merging vertex simplification to the found two vertex simplification weight values and the smallest vertex. Repeat the above steps until the required degree of simplification is met (the degree of simplification of the 3D device model, that is, the number of vertices after simplification is the percentage of the number of original vertices). The degree of simplification to meet the needs here is determined by the user according to different application environments, the distance from the viewpoint to the device, and the flexible configuration of the viewpoint orientation.

As shown in FIG. 1 , the method described in the present invention will be described in detail below taking the simplified weight values of the two vertices found and the smallest vertices being vertex u and vertex v as a preferred example.

In Figure 1, vertex u and vertex v are the two vertices that find the simplified weight value and the smallest vertex. Vertex u and vertex v are two vertices of the common side of two triangles in the 3D device model. If the vertex u and vertex v are merged Vertex v to simplify the surface of the 3D device model, the following steps need to be performed:

Remove triangles with both vertex u and vertex v as vertices.

If the simplification weight values of vertex u and vertex v are equal, remove any triangle whose vertex is the vertex (for example, remove the triangle whose vertex u is the vertex), replace vertex u with vertex v, and remove vertex u.

If the simplified weight values of vertex u and vertex v are not equal (for example, the simplified weight value of vertex v > the simplified weight value of vertex u), remove the triangle with vertex u as the vertex, replace vertex u with vertex v, and move except vertex u.

Repeat the above steps until the degree of model simplification required by the user is met. Through the above operation, 1 vertex, 2 faces and 3 edges will be removed.

In summary, using the real-time generation method of the LOD model provided by the present invention, through the real-time simplification of the three-dimensional equipment model, an approximate three-dimensional equipment model with the required resolution can be obtained in real time, and the continuity of the resolution change can be guaranteed . 3D equipment models with different degrees of simplification have different degrees of visual distortion. By introducing the simplified weight value, the key graphic information of the 3D equipment model can be preserved. After the 3D equipment model is simplified, the 3D equipment scene of the substation can be drawn more smoothly in real time, with good picture quality, and the visual information of the 3D equipment model is obtained. better reserved.

The method for real-time generation of an LOD model based on edge folding provided by the present invention has been described in detail above. For those skilled in the art, any obvious changes made to it without departing from the essential spirit of the present invention will constitute an infringement of the patent right of the present invention and will bear corresponding legal responsibilities.

Claims (6)

1., based on a LOD model Real-time Generation for edge contraction, it is characterized in that comprising the steps:

The distance of viewpoint to three dimensional device model is calculated according to viewpoint position and three dimensional device modal position;

By the simplification degree of viewpoint to the distance determination three dimensional device model of three dimensional device model;

According to the simplification degree of three dimensional device model, simplify weighted value by the vertex distance on viewpoint position and each summit of three dimensional device model each vertex position determination three dimensional device model, by viewpoint towards with each summit of three dimensional device model towards determine the summit on each summit of three dimensional device model towards simplification weighted value;

The vertex distance on each summit of comprehensive three dimensional device model simplifies weighted value and summit obtains each summit simplification weighted value towards simplification weighted value;

Simplify weighted value according to summit, simplifying the operation in real time according to the three dimensional device model based on vertex merge simplifies in real time to three dimensional device model; Wherein, the described three dimensional device model based on vertex merge simplifies the operation in real time and comprises the steps:

The summit on the traversal all summits of three dimensional device model simplifies weighted value, finds out adjacent two summits and simplifies two minimum summits of weight sum;

Remove and simplify with adjacent two summits the triangle that summit is done on two minimum summits of weight sum simultaneously;

If two summits simplification weighted values that adjacent two summits simplify weight sum minimum are equal, then remove the triangle of summit as summit of any one, replace another one summit with one of them summit, remove replaced summit;

If two summits simplification weighted values that adjacent two summits simplify weight sum minimum are unequal, then remove and simplify the triangle of the minimum summit of weighted value as summit using summit, simplifying weighted value time little summit with summit replaces summit to simplify the minimum summit of weighted value, removes summit and simplifies the minimum summit of weighted value;

Repeat above-mentioned steps, until the three dimensional device model simplification degree of satisfying the demand.

2. LOD model Real-time Generation as claimed in claim 1, it is characterized in that, described calculating viewpoint comprises further to the step of the distance of three dimensional device model:

Viewpoint position three-dimensional coordinate is determined according to current observation place;

The three-dimensional coordinate on the traversal all summits of three dimensional device model, finds out three dimensional device model vertices three-dimensional coordinate maximal value and minimum value;

Three dimensional device model center point three-dimensional coordinate is calculated according to three dimensional device model vertices three-dimensional coordinate maximal value and minimum value;

The distance of viewpoint to equipment is calculated according to viewpoint position three-dimensional coordinate and three dimensional device model center point three-dimensional coordinate.

3. LOD model Real-time Generation as claimed in claim 1, is characterized in that:

The simplification degree of described three dimensional device model configures according to the distance of viewpoint to three dimensional device model.

4. LOD model Real-time Generation as claimed in claim 1, is characterized in that, the described step determining that the vertex distance on each summit of three dimensional device model simplifies weighted value comprises further:

The distance between viewpoint and each summit of three dimensional device model is calculated according to each summit three-dimensional coordinate of viewpoint position three-dimensional coordinate and three dimensional device model;

Vertex distance according to each summit of distance determination three dimensional device model between viewpoint and each summit of three dimensional device model simplifies weighted value.

5. LOD model Real-time Generation as claimed in claim 1, is characterized in that, describedly determines that the summit on each summit of three dimensional device model comprises further towards the step simplifying weighted value:

According to the angle determination viewpoint of viewpoint position and Z axis positive dirction towards angle;

Determine that summit is towards angle according to the angle of vertex position and Z axis positive dirction;

Determine to fix a point towards simplifying weighted value towards angle and summit towards the difference of angle according to viewpoint.

6. LOD model Real-time Generation as claimed in claim 1, is characterized in that, calculates according to the following formula when described summit simplifies weighted value:

Vertex distance simplifies weighted value × 0.5+ summit and simplifies weighted value towards simplification weighted value × 0.5=summit.