CN109961515A - A kind of efficient Spatial three-dimensional dispersion model meshes reconstructing method - Google Patents
A kind of efficient Spatial three-dimensional dispersion model meshes reconstructing method Download PDFInfo
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- CN109961515A CN109961515A CN201910272220.2A CN201910272220A CN109961515A CN 109961515 A CN109961515 A CN 109961515A CN 201910272220 A CN201910272220 A CN 201910272220A CN 109961515 A CN109961515 A CN 109961515A
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Abstract
The invention discloses a kind of efficient Spatial three-dimensional dispersion model meshes reconstructing methods, include the following steps: S1: setting grid cell simultaneously sets grid operator；S2: original three-dimensional model is read, and traverses grid cell；S3: setting and simplify threshold value, and the simplified threshold definitions are the mean value of the grid operator on each vertex of the grid cell；S4: model simplification operation traverses the grid cell again, the grid operator of each grid cell and the simplified threshold value comparison deletes the qualified grid cell；The present invention can while reducing model data amount it is as much as possible retain original three-dimensional model local detail feature.
Description
Technical Field
The invention relates to the technical field of three-dimensional modeling, in particular to a high-efficiency three-dimensional space entity model grid reconstruction method.
Background
At present, with the rapid development of science and technology, the three-dimensional modeling technology and the equipment for acquiring three-dimensional data are increasingly perfected, and 3D products such as movie animation, 3D games, terrain modeling and the like gradually enter the lives of people, so that the requirements of people on the aspects of graphic accuracy and reality are met.
However, large and complex Three-Dimensional Models are common nowadays, the data volume of the Models is huge, and great problems are brought to storage, transmission, display and rendering, so that model Simplification technology slowly becomes a problem to be solved, for example, Yongzhi Wang can reduce the data volume of the Models to a certain extent while maintaining the characteristics of the Models and relieving the contradiction between data storage and model rendering by performing statistical analysis on the Geometric information of first-order adjacent points and second-order adjacent points of each vertex of the model grid cells (Yongzhi Wang, Jianwen Zheng, Hui Wang, Fast Mesh simple location method for Three-Dimensional Geometric Models with Feature-forecasting, 2019); although model simplification is a relatively mature research direction and has a great number of research methods, the problem that a certain degree of geometric features are lost when a large-scale three-dimensional model is simplified still exists.
Therefore, how to provide a three-dimensional solid model method without losing geometric features is a problem that needs to be solved urgently by those skilled in the art.
Disclosure of Invention
In view of this, the invention provides an efficient three-dimensional space entity model grid reconstruction method, which can reduce the data volume of a model, simultaneously retain local detail characteristics of an original three-dimensional model as much as possible, and simultaneously improve the algorithm efficiency.
In order to achieve the purpose, the invention adopts the following technical scheme:
a method for reconstructing a high-efficiency three-dimensional space entity model grid comprises the following steps:
s1: setting grid cells and setting grid operators, and defining a grid operator formula as follows:
wherein E (V) is a grid operator, and V represents the grid sheetOne vertex in the element, PvIs the in degree, P, of the cell vertex V of the meshvjIs the jth vertex V adjacent to the vertex VjThe in-degree of (c) is the average length of all input edges of vertices adjacent to vertex V in the mesh cell;
s2: reading an original three-dimensional model and traversing the grid unit;
s3: setting a simplified threshold value, wherein the simplified threshold value is defined as the mean value of the grid operators of all the vertexes of the grid unit;
s4: and model simplification operation, traversing the grid cells again, comparing the grid operator of each grid cell with the simplification threshold value, judging whether the grid operator meets the simplification condition, and deleting the grid cells meeting the simplification condition.
The method has the beneficial effects that: the original model is divided through the grid units, the grid operators are compared with the simplified threshold values, the grid units meeting the conditions are deleted, and the generated simplified model can effectively retain the characteristics of the original model, reduce the data volume of the model and simultaneously retain the local detail characteristics of the original three-dimensional model as much as possible.
Preferably, the step S4 further includes the steps of:
s41: when the grid operator is smaller than or equal to the simplification threshold, deleting the grid unit;
s42: adding a new vertex in a cavity area generated after the grid unit is deleted, and performing spatial reconstruction with the original three-dimensional model;
s43: and outputting the processed model.
The method has the beneficial effects that: and deleting the grid cells based on the grid operator selectively, wherein when the grid operator is low, the grid distribution is smooth, the characteristic is weak, and the influence of deleting the grid on the characteristic of the model is small, so that the grid cells with high grid operators are reserved, and the grid cells with low grid operators are deleted.
Preferably, the average length of the input edge is defined as:
wherein,is the jth vertex adjacent to vertex VThe degree of penetration of the (c) is,for the vertices of the model mesh cell adjacent to said vertex VAverage length of all input edges, LjIs the total length of the input edge.
Preferably, in step S4, when the grid operator is greater than the simplification threshold, the grid operator is weighted and the grid cell is traversed again.
Preferably, the weighting coefficient is in the range of (0, 1). The weighting coefficients have important influence on the time efficiency and the simplification degree of simplification, the larger the coefficient is, the larger the three-dimensional space model is simplified, and conversely, the smaller the energy threshold coefficient is, the smaller the model simplification degree is.
Preferably, the grid cells can also be curved cells, in which case all the simplified steps are identical to all the steps described above.
According to the technical scheme, the invention discloses the high-efficiency three-dimensional space entity model grid reconstruction method, which can generate an approximate model with relatively low precision to replace the original model, reduce the number of grid units, simultaneously reserve the local detail characteristics of the original model, effectively relieve the contradiction between a complex scene and the real-time model drawing requirement, and provide support for the three-dimensional space entity model research and application.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
FIG. 1 is a flow chart of a method for reconstructing a grid of an efficient three-dimensional spatial entity model according to the present invention;
FIG. 2 is a diagram illustrating an application effect of an embodiment 2 of a method for reconstructing a mesh of a high-efficiency three-dimensional solid model according to the present invention;
FIG. 3 is a graph showing the effect of the application of the comparative example 2 of the present invention;
FIG. 4 is a graph showing the comparison of the execution efficiency of two methods in example 2 of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
Referring to fig. 1, an embodiment 1 of the present invention provides a method for reconstructing a mesh of an efficient three-dimensional spatial entity model, including the following steps:
s1: setting grid cells and setting grid operators, and defining a grid operator formula as follows:
wherein E (V) is a mesh operator, V represents a vertex in the mesh cell, PvFor the in-degree of the vertex V of the grid cell, the number of adjacent edges connected with one vertex is the in-degree of one point, PvjIs the jth vertex V adjacent to the vertex VjThe degree of penetration of the (c) is,for vertex V adjacent to vertex V in the mesh celljAverage length of all input edges;
s2: reading an original three-dimensional model and traversing the grid unit;
s3: setting a simplified threshold value, wherein the simplified threshold value is defined as the mean value of the grid operators of all the vertexes of the grid unit;
s4: and model simplification operation, traversing the grid cells again, comparing the grid operator of each grid cell with the simplification threshold value, judging whether the grid operator meets the simplification condition, and deleting the grid cells meeting the simplification condition.
Specifically, in step S2, a mesh unit is constructed based on a half-edge data structure, where the half-edge data structure is the most common data structure for constructing a solid surface model in the solid geometric modeling technology; when the grid unit is simplified, the model is constructed by adopting a half-edge data structure, so that the traversing and querying efficiency of the model is obviously improved.
In a specific embodiment, the step S4 further includes the following steps:
s41: when the grid operator is smaller than or equal to the simplification threshold, deleting the grid unit;
s42: adding a new vertex in a cavity area generated after the grid unit is deleted, and performing spatial reconstruction with the original three-dimensional model;
s43: and outputting the processed model.
Specifically, the new vertex and the original model vertex reconstruct a spatial topological relation, and perfect a half-edge data structure of the geometric elements for reconstructing the topological relation in step S42, and recalculate the mesh operators of the corresponding vertices and the mesh cells.
In a specific embodiment, the average length of the input edges is defined as:
wherein,is the jth vertex adjacent to vertex VThe degree of penetration of the (c) is,for the vertices of the model mesh cell adjacent to said vertex VAverage length of all input edges, LjIs the total length of the input edge.
In particular, the vertexMay be first order neighboring points.
In a specific embodiment, in step S4, when the grid operator is greater than the simplification threshold, the grid operator is weighted and the grid cell is traversed again.
In a specific embodiment, the weighting factor ranges from (0, 1).
Specifically, the value of the weighting coefficient may be any one of 0.2, 0.5, and 0.8.
In a specific embodiment, the grid cells can also be surface cells.
Example 2
In order to further verify the effectiveness and the efficiency of the simplification method provided by the present invention, the method provided by the present invention and the QEM mesh simplification algorithm implemented by OpenMesh are compared and analyzed, the experimental hardware environment is a PC with a CPU of intel (r) core (tm) i7-4700U CPU @3.40GHZ and a memory of 16G, the adopted example data is a dragon model of stanford university Computer Graphics Laboratory, 47800 mesh units are included in the initial state, and the simplification result is shown in table 1-1.
TABLE 1.1 model reduced Algorithm execution time statistics Table
Referring to fig. 2-4, it can be seen that the two simplified algorithms have similar visualization effects, and both can well maintain important local detail features, but the algorithm provided herein has higher time efficiency as can be seen through time efficiency comparison analysis.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (5)
1. A method for reconstructing a grid of an efficient three-dimensional space entity model is characterized by comprising the following steps:
s1: setting grid cells and setting grid operators, and defining a grid operator formula as follows:
wherein E (V) is a mesh operator, and the vertex V represents a vertex in the mesh cell, PvFor the vertices V of the grid cellsDegree, PvIs the jth vertex V adjacent to the vertex VjThe degree of penetration of the (c) is,for the vertex adjacent to vertex V in the mesh cellAverage length of all input edges;
s2: reading an original three-dimensional model and traversing the grid unit;
s3: setting a simplified threshold value, wherein the simplified threshold value is defined as the mean value of the grid operators of all the vertexes of the grid unit;
s4: and model simplification operation, traversing the grid cells again, comparing the grid operator of each grid cell with the simplification threshold value, judging whether the grid operator meets the simplification condition, and deleting the grid cells meeting the simplification condition.
2. The method for reconstructing a mesh of an efficient three-dimensional solid model according to claim 1, wherein the step S4 further comprises the steps of:
s41: when the grid operator is smaller than or equal to the simplification threshold, deleting the grid unit;
s42: adding a new vertex in a cavity area generated after the grid unit is deleted, and performing spatial reconstruction with the original three-dimensional model;
s43: and outputting the processed model.
3. The method according to claim 1, wherein the average length of the input edge is defined as:
wherein, PvjIs the jth vertex V adjacent to the vertex VjThe degree of penetration of the (c) is,for the vertices V adjacent to said vertex V in the model mesh celljAverage length of all input edges, LjIs the total length of the input edge.
4. The method for reconstructing a mesh of an efficient three-dimensional solid model according to any one of claims 1-3, wherein in step S4, when the mesh operator is greater than the simplified threshold, the mesh operator is weighted and traversed again through the mesh cells.
5. The method according to claim 4, wherein the range of the weighting coefficients is (0, 1).
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107527384A (en) * | 2017-07-14 | 2017-12-29 | 中山大学 | A kind of lattice simplified method of Three-Dimensional Dynamic based on motion feature and its system |
| CN108961411A (en) * | 2018-07-02 | 2018-12-07 | 南京大学 | A kind of simplified method of the complex three-dimensional building model keeping external appearance characteristic |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107527384A (en) * | 2017-07-14 | 2017-12-29 | 中山大学 | A kind of lattice simplified method of Three-Dimensional Dynamic based on motion feature and its system |
| CN108961411A (en) * | 2018-07-02 | 2018-12-07 | 南京大学 | A kind of simplified method of the complex three-dimensional building model keeping external appearance characteristic |
Non-Patent Citations (1)
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| YONGZHI WANG等: "fast mesh simplification method for three-dimensional geometric models with feature-preserving efficiency", 《SCIENTIFIC PROGRAMMING》 * |
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