CN114842132A - Touch screen-based 3D model efficient picking method and device - Google Patents

Abstract

The invention belongs to the technical field of 3D model picking, and in particular relates to an efficient picking method for 3D models based on a touch screen. Each rectangular patch of the simple model is converted into a triangular patch; mark conversion: convert the screen click position information into a ray in three-dimensional space; hit judgment: pass

The algorithm judges whether the ray and the triangular patch intersect; Picking and outputting: By calculating the distance between each intersection point and the starting point of the ray, the model part picked up by clicking on the screen is determined, and it is output. The present invention is based on the touch screen-based 3D model efficient picking method, using

The algorithm to pick model parts can not only improve the picking efficiency of 3D model parts, but also effectively save a lot of memory usage space. In addition, the present invention also provides an efficient 3D model picking device suitable for the above picking method.

Description

A method and device for efficient picking up of 3D models based on touch screen

technical field

The invention belongs to the technical field of 3D model picking, and in particular relates to an efficient picking method for 3D models based on a touch screen.

Background technique

In the intelligent car entertainment system or human-computer interaction interface, more and more 3D elements are added, such as 3D car models. In the human-computer interaction interface, we generally slide the screen to view the 3D car models from different perspectives, and control the corresponding parts of the vehicle by clicking on each part in the 3D car model; for example, by clicking on the trunk of the 3D car model to Open or close the trunk of the vehicle, open or close the hood of the vehicle by clicking on the hood in the 3D car model, etc.

In the prior art, the problem of selecting and picking 3D models is generally solved by using "texture (color) picking" technology in OpenGL ES. This technology generally requires two renderings of the scene, one is called "texture picking", and the texture contains Primitive index data, and the other time is directly rendered to the actual color buffer; in which "texture picking" is often not output to the color buffer, which is invalid rendering, so this picking technology not only has low picking efficiency, but also requires a large amount of memory. space.

Therefore, designing a 3D model picking technology that can effectively improve the 3D model picking efficiency and save memory space is of decisive significance for us to efficiently identify which part of the 3D car model is selected when we click on the 3D car model on the touch screen.

SUMMARY OF THE INVENTION

算法相结合的方式，来对3D模型的各部件进行选中和拾取，相较于现有技术中需要经过两次渲染、占用较大内存空间的纹理拾取方式而言，

算法是一种快速计算射线与三角形在三个维度上的交点的方法，通过向量与矩阵计算可以快速得出交点与重心坐标，而无需对包含三角形的平面方程进行预计算；因此，采用该算法进行运算不仅可有效的提高运算的效率、提高3D模型部件被拾取的效率，而且由于该算法无需进行预计算，可有效的节省大量的内存使用空间。本发明还提供了一种适用于上述拾取方法的3D模型高效拾取装置，通过采集模块、存储模块、处理模块和控制模块的结合，可快速的采集标记点和3D模型部件的信息、并对采集的信息进行快速的运算，从而高效的判断出点击屏幕所选中和拾取的模型部件。In order to solve the shortcomings of the prior art, the present invention provides an efficient picking method for 3D models based on a touch screen.

The combination of algorithms is used to select and pick up each component of the 3D model. Compared with the texture picking method in the prior art, which requires two renderings and occupies a large memory space,

The algorithm is a method of quickly calculating the intersection of a ray and a triangle in three dimensions. The intersection and barycentric coordinates can be quickly obtained through vector and matrix calculations, without the need to pre-calculate the plane equation containing the triangle; therefore, this algorithm is used. Performing operations can not only effectively improve the efficiency of operations and the efficiency of picking up 3D model parts, but also can effectively save a lot of memory usage space because the algorithm does not need to perform pre-computation. The present invention also provides an efficient 3D model pickup device suitable for the above pickup method. Through the combination of the acquisition module, the storage module, the processing module and the control module, the information of the marked points and the 3D model components can be quickly collected, and the collected information can be quickly collected. The information is quickly calculated, so as to efficiently determine the model parts selected and picked by clicking on the screen.

The operation of the above picking method is effectively realized.

The technical effect to be achieved by the present invention is realized by the following technical solutions:

算法判断射线与三角形面片是否相交；拾取输出：通过计算各交点与射线起点的距离来确定点击屏幕所拾取的模型部件，并对其进行输出。The method for efficiently picking up 3D models based on a touch screen in the present invention includes the following steps to simplify the model: simplify each model component into a simple rectangular parallelepiped by reading model data; patch conversion: convert each rectangular patch of the simple rectangular parallelepiped into triangles Patch; mark conversion: convert the screen click position information into a ray in three-dimensional space; hit judgment: pass

The algorithm judges whether the ray and the triangular patch intersect; Picking and outputting: By calculating the distance between each intersection point and the starting point of the ray, the model part picked up by clicking on the screen is determined, and it is output.

Further, in the step of simplifying the model, including, reading data: by reading each model file to obtain all mesh data in each model file, saving it into the mesh container, and setting a corresponding name for the mesh of each model file ;Create simple model: Create a model object for the mesh of each model file, and generate a simple model of a cuboid surrounding the original mesh.

Further, in the step of creating a simplified model, including,

S1. Preset variables: The preset simplified model object contains member variables m_PointMinx, m_PointMiny, m_PointMinz; m_PointMaxx, m_PointMaxy, m_PointMaxz;

S2. Variable assignment: Compare the coordinate values X, Y, Z of each vertex in the mesh with the corresponding member variables separately, assign the smallest X value to m_PointMinx, the smallest Y value to m_PointMiny, and the smallest Z value to assign To m_PointMinz; assign the largest X value to m_PointMaxx, the largest Y value to m_PointMaxy, and the largest Z value to m_PointMaxz;

S3. Generate a simplified model: generate a simple model of a cuboid surrounding the original mesh by assigning m_PointMinx, m_PointMiny, m_PointMinz, m_PointMaxx, m_PointMaxy, and m_PointMaxz.

Further, in the step of creating a simplified model, assign values to each member variable by the following formula,

If X<m_PointMinx, then m_PointMinx=X;

If X>m_PointMaxx, then m_PointMaxx=X;

If Y<m_PointMiny, then m_PointMiny=Y;

If Y>m_PointMaxy, then m_PointMaxy=Y;

If Z<m_PointMinz, then m_PointMinz=Z;

If Z>m_PointMaxz, then m_PointMaxz=Z.

Further, in the step of creating the simplified model, the coordinates of the vertices of the simplified model of the cuboid after assignment are as follows:

vertex D0(m_PointMinx, m_PointMiny, m_PointMinz);

vertex D1(m_PointMinx, m_PointMaxy, m_PointMinz);

Vertex D2(m_PointMaxx, m_PointMaxy, m_PointMinz);

vertex D3(m_PointMaxx, m_PointMiny, m_PointMinz);

Vertex D4(m_PointMaxx, m_PointMaxy, m_PointMaxz);

Vertex D5(m_PointMinx, m_PointMaxy, m_PointMaxz);

vertex D6(m_PointMinx, m_PointMiny, m_PointMaxz);

Vertex D7(m_PointMaxx, m_PointMiny, m_PointMaxz).

Further, the mark conversion step includes: mark conversion: uniformly convert the screen click position information into corresponding pixel positions on the display screen; ray conversion: convert the two-dimensional screen coordinate information into rays in the three-dimensional space where the 3D model is located.

Further, in the mark conversion step, the screen click position information is the touched point of the screen or the point shot by the laser pointer on the display screen.

Further, in the patch conversion step, the 6 rectangular patches of the simple rectangular parallelepiped are converted into 12 triangular patches, and each triangular patch is represented by Sx(a, b, c), where x represents the number of the Triangular patch, a, b, c represent the vertex numbers of the simple cube.

Further, in the patch conversion step, the representation of the 12 triangular patches of the simple rectangular parallelepiped is as follows:

S0(D0,D1,D2), S1(D0,D2,D3), S2(D0,D6,D7),

S3(D0,D7,D3), S4(D0,D6,D5), S5(D0,D5,D1),

S6(D1,D2,D4), S7(D1,D4,D5), S8(D4,D5,D6),

S9 (D4, D6, D7), S10 (D2, D3, D4), S11 (D4, D7, D3).

Further, in the hit determination step, it is judged whether the ray intersects with the simplified rectangular parallelepiped by whether the ray intersects with the 12 triangular patches of the simplified rectangular parallelepiped.

算法的计算公式如下：Further, in the hit judgment step,

The calculation formula of the algorithm is as follows:

其中O为射线起点，

为射向方向；V0，V1，V2为三角形的三个顶点，t、u、v为标量。

where O is the starting point of the ray,

is the shooting direction; V0, V1, V2 are the three vertices of the triangle, and t, u, and v are scalars.

Further, in the hit judgment step, when t>0, 0<u<1, 0<v<1, 0<u+v<1, the intersection of the ray and the triangular patch is inside the triangular patch, and the ray and The focal coordinates of the triangular patch are

Further, in the step of picking and outputting, including, distance comparison: comparing the distances between the intersection of each model part and the ray and the starting point of the ray; selecting and outputting: selecting the model part whose intersection is the shortest from the starting point of the ray, and outputting it .

The touch-screen-based high-efficiency picking-up device for 3D models in the present invention includes: a collection module: used to collect externally inputted model component data information, as well as user's touch signal or gesture information; a storage module: used to store computer programs, and The information collected by the collection module is stored; the processing module is used to execute a computer program, convert and calculate the collected information, and output the picked up model components; and the control module: used to control the collection module and the storage module and the operation of the processing module.

Further, the acquisition module includes a model data acquisition unit: used to acquire externally inputted model component data information; and a marker point acquisition unit: used to acquire user's touch signal or gesture information.

Further, the processing module includes a conversion unit: used to convert the data information of the model components into a simple rectangular parallelepiped, and to convert externally input touch signals or gesture information into rays in three-dimensional space; a detection unit: used to detect rays Whether there is an intersection point with the simple model of the rectangular parallelepiped, and calculating the position of the intersection point, comparing the distance between each intersection point and the starting point of the ray; and an output unit for outputting the picked model parts.

To sum up, the present invention has at least the following benefits:

算法来进行模型部件拾取，相较于现有技术中在OpenGL ES使用“纹理(颜色)拾取的方式而言，不仅算法本身运算较快，无需进行多次渲染，可有效的避免无效渲染，从而提高对3D模型部件的拾取效率，而且

算法无需对包含三角形的平面方程进行预计算，可有效的节省大量的内存使用空间。1. The efficient picking method of 3D models based on the touch screen of the present invention, using

Compared with the method of using "texture (color) picking in OpenGL ES in the prior art, not only the algorithm itself is faster, but it does not need to perform multiple renderings, which can effectively avoid invalid rendering, thereby Improves picking efficiency for 3D model parts, and

The algorithm does not need to pre-compute the plane equations containing triangles, which can effectively save a lot of memory space.

2. The present invention is based on the efficient picking method of 3D models on the touch screen, and selects and judges each 3D model component by converting it into a simplified model. Compared with the complex and different shapes of the model components themselves, the simplified Model parts can greatly reduce the difficulty of operation, thereby further effectively improving the picking efficiency of 3D model parts.

算法的基础判断量需求，大大地提高运算的效率，从而更进一步有效的提高对3D模型部件的拾取效率。3. The present invention is based on a touch screen-based efficient picking method for 3D models, which is selected and judged by converting the 3D model components into a simple rectangular parallelepiped and then into triangular patches, and the converted triangular patches can satisfy the

The basic judgment demand of the algorithm greatly improves the efficiency of the operation, thereby further effectively improving the picking efficiency of the 3D model parts.

4. The high-efficiency pick-up device for 3D models based on the touch screen of the present invention can not only quickly collect the information of marked points and 3D model parts, but also perform fast operations on the collected information, so as to efficiently determine the selected and picked objects by clicking on the screen. model parts.

Description of drawings

Fig. 1 is a flow chart of an efficient method for picking up 3D models based on a touch screen in an embodiment of the present invention;

Fig. 2 is each vertex labeling diagram of the rectangular parallelepiped model in the embodiment of the present invention;

Fig. 3 is the schematic diagram that screen two-dimensional coordinate information is converted into three-dimensional space ray in the embodiment of the present invention;

算法的原理示意图；Figure 4 is an embodiment of the present invention

The schematic diagram of the algorithm;

FIG. 5 is a schematic structural diagram of an efficient pick-up device for a 3D model based on a touch screen according to an embodiment of the present invention.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. The described embodiments are some, but not all, embodiments of the present invention.

Accordingly, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Example 1:

Please refer to FIG. 1 , the method for efficiently picking up 3D models based on a touch screen in this embodiment includes the following steps:

Simplified model: Simplify each model component into a cuboid simplified model by reading model data;

Patch conversion: Convert each rectangular patch of the cuboid simple model into a triangular patch;

Mark conversion: Convert the screen click position information into rays in three-dimensional space;

算法判断射线与三角形面片是否相交；Hit Judgment: Pass

The algorithm judges whether the ray intersects the triangular patch;

Picking and output: Determine the model parts picked by clicking on the screen by calculating the distance between each intersection point and the starting point of the ray, and output it.

算法相结合的方式，来对3D模型的各部件进行选中和拾取，相较于现有技术中需要经过两次渲染、占用较大内存空间的纹理拾取方式而言，

算法是一种快速计算射线与三角形在三个维度上的交点的方法，通过向量与矩阵计算可以快速得出交点与重心坐标，而无需对包含三角形的平面方程进行预计算；因此，采用该算法进行运算不仅可有效的提高运算的效率、提高3D模型部件被拾取的效率，而且由于该算法无需进行预计算，可有效的节省大量的内存使用空间。In this embodiment, the efficient picking method of 3D model based on touch screen, through model simplification, simplified model and mark point conversion, and

Compared with the texture picking method in the prior art, which requires two renderings and occupies a large memory space,

The algorithm is a method of quickly calculating the intersection of a ray and a triangle in three dimensions. The intersection and barycentric coordinates can be quickly obtained through vector and matrix calculations, without the need to pre-calculate the plane equation containing the triangle; therefore, this algorithm is used. Performing operations can not only effectively improve the efficiency of operations and the efficiency of picking up 3D model parts, but also can effectively save a lot of memory usage space because the algorithm does not need to perform pre-computation.

Example 2:

In this embodiment, the efficient picking method for 3D models based on a touch screen includes the steps of Embodiment 1, and the main differences are:

In the simplified model step, it specifically includes the following steps,

Read data: Obtain all mesh data in each model file by reading each model file, save it in the mesh container, and set the corresponding name for the mesh of each model file, such as M1, M2, etc.; among them, the model file Refers to the 3D model file exported from the 3D model produced by the 3D software, which saves the vertex information of a series of model components, generally suffixed with .fbx, .obj, etc.

Create a simple model: Create a simple model object for the mesh of each model file, and generate a simple model of a cuboid surrounding the original mesh; in order to ensure the accuracy of judging and picking model parts, the simple model of the cuboid can only just completely surround the mesh. If the size of the simple model of the cuboid If it is too small and does not completely surround the model part, when the hit judgment is made on the model part, it is easy for the ray to intersect with the model part that exceeds the part of the simple cuboid, but it is not selected; if the size of the simple cuboid is too large, when the model part is When making hit judgment, it is easy to occur that the ray intersects with the simple model of the cuboid, but does not intersect with the model part, which not only affects the picking accuracy of the model part, but also increases the difficulty of the hit judgment calculation, thereby reducing the model part picking efficiency.

Example 3:

In this embodiment, the efficient picking method for 3D models based on a touch screen includes the steps of Embodiment 2, and the main differences are:

In the steps of creating a simple model, it includes the following steps:

S1. Preset variables: The preset simplified model object contains member variables m_PointMinx, m_PointMiny, m_PointMinz; m_PointMaxx, m_PointMaxy, m_PointMaxz;

S2. Variable assignment: Compare the coordinate values X, Y, Z of each vertex in the mesh with the corresponding member variables separately, assign the smallest X value to m_PointMinx, the smallest Y value to m_PointMiny, and the smallest Z value to assign To m_PointMinz; assign the largest X value to m_PointMaxx, the largest Y value to m_PointMaxy, and the largest Z value to m_PointMaxz;

S3. Generate a simplified model: generate a simple model of a cuboid surrounding the original mesh by assigning m_PointMinx, m_PointMiny, m_PointMinz, m_PointMaxx, m_PointMaxy, and m_PointMaxz.

Specifically, in the variable assignment step, each member variable is assigned by the following formula:

If X<m_PointMinx, then m_PointMinx=X;

If X>m_PointMaxx, then m_PointMaxx=X;

If Y<m_PointMiny, then m_PointMiny=Y;

If Y>m_PointMaxy, then m_PointMaxy=Y;

If Z<m_PointMinz, then m_PointMinz=Z;

If Z>m_PointMaxz, then m_PointMaxz=Z.

Please refer to accompanying drawing 2, the 8 vertices of the cuboid simplified model are represented by D0-D7, then the coordinates of the 8 vertices of the cuboid simplified model after the assignment are as follows:

vertex D0(m_PointMinx, m_PointMiny, m_PointMinz);

vertex D1(m_PointMinx, m_PointMaxy, m_PointMinz);

Vertex D2(m_PointMaxx, m_PointMaxy, m_PointMinz);

vertex D3(m_PointMaxx, m_PointMiny, m_PointMinz);

Vertex D4(m_PointMaxx, m_PointMaxy, m_PointMaxz);

Vertex D5(m_PointMinx, m_PointMaxy, m_PointMaxz);

vertex D6(m_PointMinx, m_PointMiny, m_PointMaxz);

Vertex D7(m_PointMaxx, m_PointMiny, m_PointMaxz).

The touch-screen-based 3D model pick-up method in Embodiments 2 and 3 selects and judges each 3D model part by converting it into a simple model. Compared with the complex and different-shaped model parts themselves, the method is simplified. The latter model parts can greatly reduce the difficulty of operation, thereby further effectively improving the picking efficiency of 3D model parts.

Example 4:

The touch screen-based efficient picking method for 3D models in this embodiment includes the steps of any one of Embodiments 1-3, and the main differences are:

In the label conversion step, it specifically includes the following steps:

Mark conversion: uniformly convert the screen click position information into the corresponding pixel position on the display screen; wherein, the screen click position information is the touched point of the screen or the point shot by the laser pointer on the display screen.

Ray conversion: Convert the two-dimensional screen coordinate information into rays in the three-dimensional space where the 3D model is located.

OpenGL transforms the three-dimensional vertex information of the 3D model through coordinate transformation: object coordinate system - world coordinate system - camera coordinate system - clipping space - standard device space - actual window space, and finally converts it into two-dimensional screen information; two-dimensional screen coordinates are Through the above inverse transformation: actual window space - standard device space - clipping space - camera coordinate system - world coordinate system, it can be converted into a three-dimensional space vertex. Among them, a hexahedral space is customized in the clipping space conversion (through parameter configuration settings, which exists in the form of a matrix in OpenGL) to clip the content seen by the camera, and define the front plane close to the camera as the near plane, far from the camera. The front plane is the far plane; then, the two-dimensional pixel coordinates of the screen can be converted to obtain the vertex (point B) of the near plane and the vertex (point A) on the far plane in the observation space, as shown in Figure 3.

Example 5:

The touch screen-based efficient 3D model picking method in this embodiment includes the steps of any one of Embodiments 1-4, and the main differences are:

In the patch conversion step, the 6 rectangular patches of the cuboid simplified model are converted into 12 triangular patches, each triangular patch is represented by Sx(a, b, c), where x represents the number of the triangular patch , a, b, c represent the vertex numbers of the simple model of the cuboid. It can be concluded that the representation of the 12 triangular patches of the simple model of the cuboid is as follows:

S0(D0,D1,D2), S1(D0,D2,D3), S2(D0,D6,D7),

S3(D0,D7,D3), S4(D0,D6,D5), S5(D0,D5,D1),

S6(D1,D2,D4), S7(D1,D4,D5), S8(D4,D5,D6),

S9 (D4, D6, D7), S10 (D2, D3, D4), S11 (D4, D7, D3).

In the hit judgment step, it is judged whether the ray intersects with the simplified rectangular parallelepiped by whether the ray intersects with the 12 triangular facets of the simplified rectangular parallelepiped.

Example 6:

The touch screen-based efficient picking method for 3D models in this embodiment includes the steps in Embodiment 5, and the main differences are:

算法的计算公式如下：In the hit judgment step,

The calculation formula of the algorithm is as follows:

为射向方向，既顶点B到顶点A的方向向量；V0，V1，V2为三角形的三个顶点；t、u、v为标量，其中u为V1的权重，v为V2的权重，1-u-v是V0的权重。where O is the starting point of the ray;

is the shooting direction, that is, the direction vector from vertex B to vertex A; V0, V1, V2 are the three vertices of the triangle; t, u, v are scalars, where u is the weight of V1, v is the weight of V2, 1- uv is the weight of V0.

Please refer to Fig. 4, a point V in the triangle can be understood as moving a distance along the side V0V1, and then moving along the side V0V2 for a distance, and finally find their sum vector; as for the distance to move, it is determined by the parameter u and v control, so the calculation formula is an equation that can express the triangle and all the points inside it. Therefore, when t>0, 0<u<1, 0<v<1, 0<u+v<1, the intersection of the ray and the triangular patch is inside the triangular patch, and the focal coordinates of the ray and the triangular patch are

算法的基础判断量需求，大大地提高运算的效率，从而更进一步有效的提高对3D模型部件的拾取效率。The touch-screen-based 3D model pick-up method in Embodiments 5 and 6 selects and judges the 3D model components by converting them into simple rectangular parallelepipeds and then into triangular patches, and the converted triangular patches can satisfy the

The basic judgment demand of the algorithm greatly improves the efficiency of the operation, thereby further effectively improving the picking efficiency of the 3D model parts.

Example 7:

The touch screen-based efficient picking method for 3D models in this embodiment includes the steps of any one of Embodiments 1-6, and the main differences are:

In the step of picking up the output, it specifically includes the following steps,

Distance comparison: Compare the distance between the intersection of each model component and the ray and the starting point of the ray; after calculating the intersection position of each model component and the ray, calculate the distance from each intersection to the near-plane vertex (point B). .

Selected output: Select the model part whose intersection point is the shortest from the ray start point, and output it; both the model part corresponding to the intersection point with the shortest distance from the near plane vertex (point B) is the truly selected model, and output it.

Example 8:

Referring to Figure 5, the touch screen-based 3D model high-efficiency pick-up device in this embodiment includes,

Collection module 100: used to collect externally input model component data information, and user touch signals or gesture information; wherein, the collection module includes a model data acquisition unit used to acquire externally input model component data information, and a model data acquisition unit used to collect A marker point collection unit for the user's touch signal or gesture information.

Storage module 200: used for storage of computer programs (such as OpenGL), and storage of information collected by the collection module;

Processing module 300: used to execute a computer program, convert and calculate the collected information, and output the picked model parts; wherein, the processing module includes data information for converting model parts into a simple rectangular solid model, and converting externally inputted model parts. A conversion unit that converts touch signals or gesture information into a three-dimensional space ray; a detection unit used to detect whether there is an intersection between the ray and the simple rectangular parallelepiped, calculate the position of the intersection, and compare the distance between each intersection from the starting point of the ray; The output unit of the model part.

And the control module 400: used to control the operation of the acquisition module, the storage module and the processing module.

The high-efficiency picking device for 3D models based on the touch screen in this embodiment can not only quickly collect the information of markers and 3D model parts, but also perform quick operations on the collected information, so as to efficiently determine the selected and picked objects by clicking on the screen. model parts.

算法相结合的方式，来对3D模型的各部件进行选中和拾取，不仅可有效的提高运算的效率、提高3D模型部件被拾取的效率，而且由于该算法无需进行预计算，可有效的节省大量的内存使用空间。本发明还提供了一种适用于上述拾取方法的3D模型高效拾取装置，通过采集模块、存储模块、处理模块和控制模块的结合，可快速的采集标记点和3D模型部件的信息、并对采集的信息进行快速的运算，从而高效的判断出点击屏幕所选中和拾取的模型部件。It can be seen from the technical solutions of the above embodiments that the present invention provides an efficient picking method for 3D models based on a touch screen.

Algorithms are combined to select and pick each part of the 3D model, which can not only effectively improve the efficiency of the operation and the picking efficiency of the 3D model parts, but also save a lot of money because the algorithm does not require pre-calculation. of memory usage. The present invention also provides an efficient 3D model pickup device suitable for the above pickup method. Through the combination of the acquisition module, the storage module, the processing module and the control module, the information of the marking points and the 3D model components can be quickly collected, and the collected information can be quickly collected. The information is quickly calculated, so as to efficiently determine the model parts selected and picked by clicking on the screen.

Although the present invention has been described in conjunction with the above specific embodiments, it will be apparent to those skilled in the art that many substitutions, modifications and changes can be made in light of the above. Accordingly, all such alternatives, modifications and changes are intended to be included within the spirit and scope of the appended claims.

Claims (16)

1. a 3D model efficient picking method based on a touch screen, is characterized in that, comprises the following steps, Simplified model: Simplify each model component into a cuboid simplified model by reading model data; Patch conversion: Convert each rectangular patch of the cuboid simple model into a triangular patch; Mark conversion: Convert the screen click position information into rays in three-dimensional space; Hit Judgment: Pass

The algorithm judges whether the ray intersects the triangular patch; Picking and output: Determine the model parts picked by clicking on the screen by calculating the distance between each intersection point and the starting point of the ray, and output it. 2. The efficient 3D model picking method according to claim 1, wherein in the step of simplifying the model, comprising: Read data: Get all mesh data in each model file by reading each model file, save it in the mesh container, and set the corresponding name for the mesh of each model file; Create a simple model: Create a model object for the mesh of each model file, and generate a simple model of a cuboid surrounding the original mesh. 3. The efficient 3D model picking method according to claim 2, wherein, in the step of creating a simplified model, comprising: S1. Preset variables: The preset simplified model object contains member variables m_PointMinx, m_PointMiny, m_PointMinz; m_PointMaxx, m_PointMaxy, m_PointMaxz; S2. Variable assignment: Compare the coordinate values X, Y, Z of each vertex in the mesh with the corresponding member variables separately, assign the smallest X value to m_PointMinx, the smallest Y value to m_PointMiny, and the smallest Z value to assign To m_PointMinz; assign the largest X value to m_PointMaxx, the largest Y value to m_PointMaxy, and the largest Z value to m_PointMaxz; S3. Generate a simplified model: Generate a simple model of a cuboid surrounding the original mesh by assigning m_PointMinx, m_PointMiny, m_PointMinz, m_PointMaxx, m_PointMaxy, and m_PointMaxz. 4. The 3D model efficient picking method according to claim 3, wherein in the step of creating a simplified model, each member variable is assigned a value by the following formula, If X<m_PointMinx, then m_PointMinx=X; If X>m_PointMaxx, then m_PointMaxx=X; If Y<m_PointMiny, then m_PointMiny=Y; If Y>m_PointMaxy, then m_PointMaxy=Y; If Z<m_PointMinz, then m_PointMinz=Z; If Z>m_PointMaxz, then m_PointMaxz=Z. 5. 3D model efficient picking method according to claim 3, is characterized in that, in the step of creating simplified model, the coordinates of each vertex of the cuboid simplified model after the assignment are as follows: vertex D0(m_PointMinx, m_PointMiny, m_PointMinz); vertex D1(m_PointMinx, m_PointMaxy, m_PointMinz); vertex D2(m_PointMaxx, m_PointMaxy, m_PointMinz); vertex D3(m_PointMaxx, m_PointMiny, m_PointMinz); Vertex D4(m_PointMaxx, m_PointMaxy, m_PointMaxz); Vertex D5(m_PointMinx, m_PointMaxy, m_PointMaxz); vertex D6(m_PointMinx, m_PointMiny, m_PointMaxz); Vertex D7(m_PointMaxx, m_PointMiny, m_PointMaxz). 6. The efficient 3D model picking method according to claim 1, characterized in that, in the mark conversion step, comprising: Mark conversion: uniformly convert the screen click position information into the corresponding pixel position on the display screen; Ray conversion: Convert the two-dimensional screen coordinate information into rays in the three-dimensional space where the 3D model is located. 7 . The efficient 3D model picking method according to claim 1 , wherein, in the mark conversion step, the screen click position information is a touched point of the screen or a point shot by a laser pointer on the display screen. 8 . 8. The method for efficiently picking up 3D models according to claim 1, wherein, in the patch conversion step, 6 rectangular patches of the simple rectangular parallelepiped are converted into 12 triangular patches, and each triangular patch uses Sx (a,b,c) is represented, where x represents the number of triangular facets, and a,b,c represents the vertex number of the simplified cuboid. 9. The efficient 3D model picking method according to claim 8, wherein, in the patch conversion step, the representations of 12 triangular patches in a simple rectangular parallelepiped are as follows: S0(D0,D1,D2), S1(D0,D2,D3), S2(D0,D6,D7), S3(D0,D7,D3), S4(D0,D6,D5), S5(D0,D5,D1), S6(D1,D2,D4), S7(D1,D4,D5), S8(D4,D5,D6), S9 (D4, D6, D7), S10 (D2, D3, D4), S11 (D4, D7, D3). 10 . The efficient 3D model picking method according to claim 1 , wherein, in the hit judgment step, it is judged whether the ray intersects with the simplified cuboid model by whether the ray intersects with 12 triangular facets of the simplified cuboid model. 11 . 11. 3D model efficient picking method according to claim 1, is characterized in that, in hit judgment step,

The calculation formula of the algorithm is as follows:

where O is the starting point of the ray,

is the shooting direction; V0, V1, V2 are the three vertices of the triangle, and t, u, and v are scalars. 12. The efficient 3D model picking method according to claim 11, wherein in the hit judgment step, when t>0, 0<u<1, 0<v<1, 0<u+v<1 , the intersection of the ray and the triangular patch is inside the triangular patch, and the focal coordinates of the ray and the triangular patch are

13. The efficient 3D model picking method according to claim 1, characterized in that, in the picking and outputting step, comprising: Distance comparison: Compare the distance between the intersection of each model part and the ray and the starting point of the ray one by one; Select Output: Select the model part with the shortest intersection point from the starting point of the ray, and output it. 14. An efficient 3D model pick-up device based on a touch screen, characterized in that, comprising: a collection module: used to collect externally input model component data information, and user touch signal or gesture information; Storage module: used for storage of computer programs, and storage of the information collected by the collection module; Processing module: used to execute a computer program, convert and calculate the collected information, and output the picked model parts; and a control module: used to control the operation of the acquisition module, the storage module and the processing module. 15. The efficient 3D model picking device according to claim 14, wherein the acquisition module comprises: Model data acquisition unit: used to acquire externally input model component data information; and a marker point collection unit: used to collect the user's touch signal or gesture information. 16. The efficient 3D model picking device according to claim 14, wherein the processing module comprises: Conversion unit: used to convert the data information of the model parts into a simple rectangular model, and to convert the touch signal or gesture information input from the outside into rays of three-dimensional space; Detection unit: It is used to detect whether there is an intersection between the ray and the simple model of the cuboid, calculate the position of the intersection, and compare the distance between each intersection from the starting point of the ray; and an output unit for outputting the picked model parts.

Images