CN108595858B - BIM-based lightweight advanced treatment working method - Google Patents
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Abstract
The invention provides a BIM-based lightweight advanced treatment working method, which comprises the following steps: s1, acquiring BIM original data and attribute information needing light weight, and setting light weight working parameters for conversion; s2, reading each geometric figure original data and geometric figure attribute information in BIM original data, analyzing the geometric figure original data by the light-weight working parameters, and analyzing the geometric figure attribute information, thereby optimizing the quantities of the geometric figure original data and the geometric figure attribute information; and S3, optimizing and calculating the original data of the geometric figure and the attribute information of the geometric figure, obtaining a BIM lightweight advanced processing file for format conversion, and meeting the display requirements of users.
Description
Technical Field
The invention relates to the field of BIM software optimization, in particular to a light weight advanced processing working method based on BIM.
Background
In the large-scale engineering construction field, the BIM software is used for engineering planning construction in the aspect of more and more engineering construction, so that the utilization rate of the BIM is improved, and sufficient theoretical support is provided for actual construction, but in the current BIM using process, a plurality of technical problems occur:
1. the existing light-weight technology focuses on a certain specialty of the civil engineering industry, and a BIM model light-weight technology platform aiming at multiple specialties of the civil engineering industry is not provided;
2. the current lightweight BIM platform does not deeply relate to the reprocessing technology of the lightweight BIM model, such as re-chartlet rendering, model display optimization setting and the like;
3. the light-weight technology aiming at the BIM three-dimensional model with various source formats is not provided.
Based on the above-mentioned situations, it is necessary for those skilled in the art to solve the corresponding technical problems.
Disclosure of Invention
The invention aims to at least solve the technical problems in the prior art, and particularly creatively provides a light weight advanced treatment working method based on BIM.
In order to achieve the above object, the present invention provides a light weight advanced treatment method based on BIM, comprising the steps of:
s1, acquiring BIM original data and attribute information needing light weight, and setting light weight working parameters for conversion;
s2, reading each geometric figure original data and geometric figure attribute information in BIM original data, analyzing the geometric figure original data by the light-weight working parameters, and analyzing the geometric figure attribute information, thereby optimizing the quantities of the geometric figure original data and the geometric figure attribute information;
and S3, optimizing and calculating the original data of the geometric figure and the attribute information of the geometric figure, obtaining a BIM lightweight advanced processing file for format conversion, and meeting the display requirements of users.
Preferably, the BIM-based lightweight advanced treatment method in the S1 includes:
s1-1, adopting a modeling kernel with a three-dimensional geometric modeling component ACIS and a 3D solid modeling component Parasolidd for BIM original geometric primitives, acquiring discrete data and organizing a data structure through an application program interface API; the data structure is adaptive to different versions, Business logic function Interface Business Interface interfaces are defined, working modules of different versions inherit and realize the Business Interface interfaces, and corresponding working modules are instantiated according to different versions through an internal matching method;
s1-2, dividing the geometric data into point sets and point indexes forming a patch;
s1-3, if the obtained patch is not a triangular patch, splitting the existing data and remapping the point index, otherwise, directly storing the point set and the index data of the patch;
polyhedral grid consisting of mixed patches, polygonal patches (n) of different numbers of edges>3, n is the number of edges), there is a set of vertices (pt)1、pt2、pt3……ptn) To find out
And
and vector angles, and reorganizing the main index data structure of the patch from small to large according to the magnitude of the vector angles: {3, 0, 1, 2 …..3, 15, 17, 20 … … 3, n-3, n-2, n-1}, 3 denotes a triangular patch, followed by three numbers indicating the indices of its vertices in the set of principal points;
and (3) carrying out grid vector distribution adjustment on the data so as to ensure the consistency of the front side and the back side:
A. the vectors are distributed according to each patch forming the grid, and then the original data is directly adopted; for the mesh subjected to splitting processing, vector data is associated to each new triangular patch;
B. the vectors are distributed according to each surface of the grid, if the number of the grid point sets is greater than the number of the vector distribution, the vectors at the last position of the vector set are adopted for completion, otherwise, if the number of the grid point sets is less than the number of the vector distribution, the rear-end vectors are directly abandoned, and if the number of the grid point sets is equal to the number of the vector distribution, the original data are directly adopted;
s1-4, calculating two-dimensional horizontal and vertical coordinate system UV information of the grid patch;
s1-5, extracting material information attached to the geometric surface, and analyzing the material information, including color, illumination and texture pictures;
s1-6, dispersing a NURBS curved surface (a non-uniform rational B spline surface), and setting parameters of a precision range, a pitch and a vector angle, so as to control the appearance of the NURBS curved surface to avoid distortion;
s1-7, the storage mode and the structure type of the BIM attribute information have diversity, so that the attribute extraction needs to be respectively processed according to different conditions;
aiming at the difference of storage modes and structure types, a label data processing module, a link data processing module and an extended attribute XAttributes processing module are respectively created, and after data are extracted by each module, the data are associated with geometric primitives and model tree nodes according to unique identifiers;
and S1-8, for the diversity of data types, extracting the attributes and methods of the data types by adopting a net reflection mechanism, and finally converting the finally obtained value information into character string types and outputting the character string types.
Preferably, the BIM-based lightweight advanced treatment method in the S2 includes:
s2-1, performing discrete sampling on the geometric point set data which cannot be processed in S1 to establish a basic data point model, substituting different calculation methods for different characteristics of the basic data point model to obtain a regular data point set and a patch index array;
and (3) carrying out data optimization on the basic data point model by adopting a point cloud self-adaptive slicing method:
determining the thickness of each layer of slices according to a given error, carrying out preliminary slicing on a point cloud model at a characteristic point, dividing the point cloud into a plurality of intervals, and then determining whether the interval needs to be subdivided according to the maximum distance from the point to a B spline curve, wherein the method relates to the fitting of the B spline curve;
II, reading all point cloud data into a linked list Plist, and performing space secondary grid division and K neighbor calculation;
III, the scattered point clouds have no obvious set distribution information and present a scattered disordered state, so that a topological relation among data points must be established to search K neighbors of each point;
in a point Cloud model generated by setting BIM original data and attribute information, a formed measuring point set is Cloud ═ p1,p2,......,pn},pnE is R3, if any measuring point p is E is Cloud, the k point closest to the measuring point p is called as the k neighborhood of p; wherein R3 refers to the minimum volume of the grid bounding box;
s2-2, calculating the side length L' of the grid by the point cloud data point, wherein the calculation formula is as follows,
estimating average point distance d by using number of non-empty grids, dividing side length L' and number of data pointsavgAdopting the average point distance to perform quadratic rasterization, calculating the final grid side length L, and classifying each data point into a corresponding grid on the basis of the final grid side length L, thereby calculating
According to K neighbor, solving neighborhood curvature value K (p) of each pointi) And according to k (p) of each pointi) Sequentially classifying the points into four point sets respectively, and then marking the points as S1, S2 and S3 respectively according to the intervals; find out
The subscript i, j is a positive integer, v is a function of solving an absolute value by referring to a feature vector and fabs, and the precision is a double-precision floating point type;
according to the neighborhood curvature of the point cloud midpoint calculated by the K neighbor, respectively storing the points with the neighborhood curvatures larger or smaller than gamma,
the formula for gamma is
γ is a reference threshold value for the defined approximate feature point, and σ is an adjustment factor.
Preferably, the BIM-based lightweight advanced treatment method in the S3 includes:
s3-1, the control formula of the triangle B spline curve type of any topology is as follows:
the determinant function of the above-mentioned point distance formula d (·.,..,) verifies the linear combination of the control points (); judging according to the series to obtain a triangular B spline curve control point set of the complex model curved surface; c represents a control point; t represents the proximity point around the control point, β is used to mark points at different positions in the linear group;
s3-2, processing of different grid patterns:
optimizing a Grid data conversion Grid into a triangular patch, wherein the Grid pattern comprises a multi-surface Grid Multi (n >4), a triangular Grid Triangle (n is 3), a quadrilateral Grid Quad and an array with 3 logically formed vertexes as a line, each line represents a trilateral Grid Triangle List, 4 logically formed vertexes as an array with a line, each line represents a quadrilateral Grid Quad List, and because the expression forms are inconsistent and the data organization modes are different, the program can cope with the situation of variable patterns by combining the program structure with the design mode, the self-adaptive respective processing is realized, and the unified data format is finally output;
s3-3, dividing the face slice into minimum units:
according to the point set and the indexes of the points forming the surface in the point set, remapping the points according to the rule of a triangular surface patch to obtain the main index data of a new surface patch;
s3-4, attribute:
due to the diversity of formats, the association relation between the attributes and the geometric primitives is not uniform; and after all the attributes are taken out in a self-adaptive manner through the corresponding module, writing the attributes into a sqlite lightweight database of the relational database management system, creating a corresponding table, and setting related main keys in the table, so that the association between the geometric primitives and the attributes is facilitated during later-period display.
Preferably, the BIM-based lightweight advanced treatment method, in which the step S3 further includes:
layering the three-dimensional model into a group of horizontal contour lines, filling the contour line regions in various modes to form thin layers, and superposing the thin layers in the height direction to generate a physical model; one triangular mesh in the scattered triangular set after model discretization always has three edges shared by only three other adjacent triangles; searching a group of triangles intersected with a certain horizontal section plane from the scattered triangle set in sequence, and respectively calculating the section lines of the triangles to form one or more closed polygons;
the triangular edge is represented as: one isThree z-coordinate values of the triangle are respectively zmax，zminAnd zmidThere are three distributions: the z values of the three vertexes are different from each other; there are two vertices of maximum z-value; there are two minimum z-value vertices; the correlation formula used is:
the light weight advanced treatment working method based on BIM preferably further comprises the following steps:
many models are complete and complex space curved surfaces, a single curved surface is often difficult to meet the requirement of describing complex shapes, the traditional method generally adopts a B-spline surface technology to construct the model, however, N edges cannot be used to construct a transitional N edge region under some conditions, the traditional construction method cannot be applied under the conditions, and therefore, a combined curved surface must be adopted; a synthetic curved surface with a smooth degree is constructed by the method, so that the purpose of designing the appearance of any curved surface is achieved; the related API can freely adjust the shape of the splicing curved surface by adjusting 2 set parameters and keep G2Continuously;
g of curved surfacenThe equation of the spliced curved surface is as follows:
φx＝S(s,t)＝f(t)S1(S,t)+(1-f(t))S2(s,t)，
t∈[0,1],s∈[S1,S2]，
the control point is corrected to satisfy G1One condition in succession:
satisfies G2One condition in succession:
the control point b can be calculated according to the geometric property of the triangle3Coordinate values of
And storing the corrected information from the control point to the topological structure for later-stage triangle B-threads type control processing.
In the method for performing light weight advanced treatment based on BIM, it is preferable that the sampling mode in S1 is to selectively sample mountains, depressions, bottlenecks, and boundary feature points; and the light weight effect is achieved through special treatment on the regular grid model, the contour line model and the irregular triangular net model.
In the BIM-based lightweight advanced processing method, preferably, the obtained lightweight file is a lightweight model file in a suffix-3 gd format.
In summary, due to the adoption of the technical scheme, the invention has the beneficial effects that:
the invention has the advantages that the BIM technology is taken as a basis, the light-weight technical thought and method are taken as a center, the problem of a light-weight multi-professional BIM model is solved, the BIM model with large data volume is analyzed according to a geometric algorithm, and meanwhile, the corresponding attribute information data is integrated and managed, so that the light weight of the BIM model is realized. The BIM model of realizing many professions fast, many formats is lightweight, improves the efficiency of lightweight model simultaneously, satisfies different configuration user's browsing demand and data management demand, improves the work efficiency of BIM data show for the engineering construction progress.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1 is a general schematic of the present invention;
fig. 2 is a schematic view of the present invention for weight reduction.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.
As shown in fig. 1 and 2, the invention provides a light weight advanced treatment working method based on BIM, comprising the following steps:
the method comprises the steps of obtaining BIM original data and attribute information which need to be light-weighted for one imported BIM original data, setting and matching the converted light-weighted data, importing working parameters, conducting reading operation and geometric figure attribute information reading operation on each geometric figure original data in the BIM original data, analyzing the geometric figure original data by the light-weighted working parameters, analyzing the geometric figure attribute information, optimizing the quantities of the geometric figure original data and the geometric figure attribute information, optimizing and calculating the geometric figure original data and the geometric figure attribute information, obtaining a BIM light-weighted depth processing file for format conversion, and meeting the display requirements of users.
Preferably, the S1 includes:
s1-1, adopting a modeling kernel with a three-dimensional geometric modeling component ACIS and a 3D solid modeling component Parasolidd for BIM original geometric primitives, acquiring discrete data and organizing a data structure through an application program interface API; the data structure is adaptive to different versions, Business logic function Interface Business Interface interfaces are defined, working modules of different versions inherit and realize the Business Interface interfaces, and corresponding working modules are instantiated according to different versions through an internal matching method;
s1-2, dividing the geometric data into point sets and point indexes forming a patch;
s1-3, if the obtained patch is not a triangular patch, splitting the existing data and remapping the point index;
polyhedral grid consisting of mixed patches, polygonal patches (n) of different numbers of edges>3, n is the number of edges), there is a set of vertices (pt)1、pt2、pt3……ptn) To find out
And
and (3) vector angles, and reorganizing the main index data structure of the patch from small to large according to the magnitude of the vector angles as follows: (e.g., 3, 1, 0, 3), 3 represents a triangular patch, followed by three numbers representing the indices of its vertices in the set of principal points;
adjusting the distribution of the grid vectors:
the vectors are distributed according to each patch forming the grid, and then the original data is directly adopted; for the mesh subjected to splitting processing, vector data is associated to each new triangular patch; 2. the vectors are distributed according to each surface of the grid, and if the number of the grid point sets is greater than the number of the vector distribution, the vectors at the last position of the vector set are adopted for completion;
s1-4, calculating two-dimensional horizontal and vertical coordinate system UV information of the grid patch;
s1-5, extracting material information attached to the geometric surface, and analyzing the material information, including color, illumination and texture pictures;
s1-6, dispersing the non-uniform rational B-spline surface NURBS surface, setting parameters of the depth of the precision range and the vector angle, and controlling the appearance of the NURBS surface to avoid distortion;
s1-7, the storage mode and the structure type of the BIM attribute information are various, so that the attribute extraction needs to be carried out according to different conditions;
creating a tag data processing module, a link data processing module and an extended attribute XAttributes processing module, wherein after each module extracts data, each module is associated with a geometric primitive and a model tree node according to a unique identifier;
and S1-8, for the diversity of data types, extracting the attributes and methods of the data types by adopting a net reflection mechanism, and finally converting the finally obtained value information into character string types and outputting the character string types.
Preferably, the BIM-based lightweight advanced treatment method in the S2 includes:
s2-1, performing discrete sampling on the geometric point set data which cannot be processed in S1 to establish a basic data point model, substituting different calculation methods for different characteristics of the basic data point model to obtain a regular data point set and a patch index array.
By using the point cloud adaptive slicing method,
determining the thickness of each layer of slices according to a given error, carrying out preliminary slicing on a point cloud model at a characteristic point, dividing the point cloud into a plurality of intervals, and then determining whether the interval needs to be subdivided or not according to the maximum distance from the point to a B spline curve, wherein the method relates to the fitting of the B spline curve;
reading all point cloud data into a linked list Plist, and performing space secondary grid division and K nearest neighbor calculation;
the scattered point cloud has no obvious set distribution information and presents a scattered disordered state, so that a topological relation among data points must be established to search K neighbors of each point;
in a point Cloud model generated by setting BIM original data and attribute information, a formed measuring point set is Cloud ═ p1,p2,......,pn},pnE is R3, if any measuring point p is E is Cloud, the k point closest to the measuring point p is called as the k-neighborhood of p; wherein R3 refers to the minimum volume of the grid bounding box
S2-2, calculating the side length L' of the grid by the point cloud data point, wherein the calculation formula is as follows,
estimating average point distance d by using number of non-empty grids, dividing side length L' and number of data pointsavgAdopting the average point distance to perform quadratic rasterization, calculating the final grid side length L, and classifying each data point into a corresponding grid on the basis of the final grid side length L, thereby calculating
According to K neighbor, solving neighborhood curvature value K (p) of each pointi) And according to k (p) of each pointi) Sequentially classifying the points into four point sets respectively, and then marking the points as S1, S2, S3 and S4 respectively according to the intervals; find out
The subscript i, j is a positive integer, v is a function of solving an absolute value by referring to a feature vector and fabs, and the precision is a double-precision floating point type;
according to the neighborhood curvature of the point cloud midpoint calculated by the K neighbor, respectively storing the points with the neighborhood curvatures larger or smaller than gamma,
is calculated by the formula
Gamma is a reference threshold value of the defined approximate characteristic point, and sigma is an adjusting factor;
preferably, the BIM-based lightweight advanced treatment method in the S3 includes:
s3-1, the control formula of the triangle B spline curve type of any topology is as follows:
the above-described point-distance formula d (·. ) a determinant function verifies a linear combination of control points (). Judging according to the series to obtain a triangular B spline curve control point set of the complex model curved surface; c represents a control point; t represents the proximity point around the control point, β is used to mark points at different positions in the linear group;
s3-2, processing of different grid patterns:
optimizing Grid data conversion Grid to be Triangle patch, Grid style has multiaspect net multiple (n >4), Triangle Grid (n is 3), quadrilateral mesh Quad Grid, 3 summits that constitute logically are the array of a line, each line represents a trilateral mesh Triangle List, 4 summits that constitute logically are the array of a line, each line represents a quadrilateral mesh Quad List, because the presentation form is inconsistent, the organization mode of data is different, therefore the procedure is coping with the situation that the style is changeable, combine the design mode through the program structure, accomplish self-adaptation and handle respectively, and finally output unified data format
S3-3, dividing the face slice into minimum units:
and remapping the point sets according to the point sets and indexes of the points forming the surface in the point sets according to the rule of the triangular surface patch to obtain the main index data of the new surface patch.
S3-4, attribute:
due to the diversity of formats, the association relationship between the attributes and the geometric primitives is not uniform. And after all the attributes are taken out in a self-adaptive manner through the corresponding module, writing the attributes into a sqlite lightweight database of the relational database management system, creating a corresponding table, and setting related main keys in the table, so that the association between the geometric primitives and the attributes is facilitated during later-period display.
Preferably, the BIM-based lightweight advanced treatment method, in which the step S3 further includes:
the three-dimensional model is layered into a group of horizontal contour lines, the contour line areas are filled in various modes to form thin layers, and the thin layers are overlapped in the height direction to generate the physical model. One triangular mesh in the discretized model discretized triangulated triangle set always has only three other adjacent triangles sharing its three edges. A group of triangles intersected with a certain horizontal section plane is searched from the scattered triangle set in sequence, and the section lines of the triangles are respectively calculated to form one or more closed polygons.
The triangular edge is represented as: three z-coordinate values of a triangle are zmax，zminAnd zmidThere are three distributions: z values of three vertices each otherDifferent; there are two vertices of maximum z-value; there are two minimum z-value vertices; the correlation formula used is:
the light weight advanced treatment working method based on BIM preferably further comprises the following steps:
many models are complete and complex space curved surfaces, a single curved surface often cannot meet the requirement of describing complex shapes, the traditional method generally adopts a B-spline surface technology to construct the model, however, N edges cannot be used for constructing a transitional N edge region in some cases, the traditional construction method cannot be applied in the case, and therefore, a combined curved surface is required to be adopted. The synthetic curved surface with smooth degree is constructed to achieve the purpose of designing the appearance of any curved surface. The relevant API was able to freely adjust the shape of the curved surface of the splice by adjusting 2 set parameters and keep G2 continuous.
The equation of the Gn splicing curved surface of the curved surface is as follows:
φx＝S(s,t)＝f(t)S1(S,t)+(1-f(t))S2(s,t)，
t∈[0,1],s∈[S1,S2]，
the control point is corrected to satisfy G1One condition in succession:
satisfies G2One condition in succession:
the control point b can be calculated according to the geometric property of the triangle3Coordinate values of
And storing the corrected information from the control point to the topological structure for later-stage triangle B-threads type control processing.
Preferably, the sampling mode in S1 is to selectively sample peaks, depressions, bottlenecks and boundary feature points; and achieving the lightweight effect by special processing of the regular grid model, the contour line model and the irregular triangulation network model, wherein the obtained lightweight file is a suffix-3 gd-format lightweight model file.
While embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.
Claims (6)
1. A BIM-based lightweight advanced treatment working method is characterized by comprising the following steps:
s1, acquiring BIM original data and attribute information needing light weight, and setting light weight working parameters for conversion;
s2, reading each geometric figure original data and geometric figure attribute information in BIM original data, analyzing the geometric figure original data by the light-weight working parameters, and analyzing the geometric figure attribute information, thereby optimizing the quantities of the geometric figure original data and the geometric figure attribute information;
the S2 includes:
s2-1, performing discrete sampling on the geometric point set data which cannot be processed in S1 to establish a basic data point model, substituting different calculation methods for different characteristics of the basic data point model to obtain a regular data point set and a patch index array;
and (3) carrying out data optimization on the basic data point model by adopting a point cloud self-adaptive slicing method:
determining the thickness of each layer of slices according to a given error, carrying out preliminary slicing on a point cloud model at a characteristic point, dividing the point cloud into a plurality of intervals, and then determining whether the interval needs to be subdivided according to the maximum distance from the point to a B spline curve, wherein the method relates to the fitting of the B spline curve;
II, reading all point cloud data into a linked list Plist, and performing space secondary grid division and K neighbor calculation;
III, the scattered point clouds have no obvious set distribution information and present a scattered disordered state, so that a topological relation among data points must be established to search K neighbors of each point;
in a point Cloud model generated by setting BIM original data and attribute information, a formed measuring point set is Cloud ═ p1，p2，......，pn}，pnE is R3, if any measuring point p is E is Cloud, the k point closest to the measuring point p is called as the k neighborhood of p; wherein R3 refers to the minimum volume of the grid bounding box;
s2-2, calculating the side length L' of the grid by the point cloud data point, wherein the calculation formula is as follows,
estimating average point distance d by using number of non-empty grids, dividing side length L' and number of data pointsavgAdopting the average point distance to perform quadratic rasterization, calculating the final grid side length L, and classifying each data point into a corresponding grid on the basis of the final grid side length L, thereby calculating
According to K neighbor, solving neighborhood curvature value K (p) of each pointi) And according to k (p) of each pointi) Sequentially classifying the points into four point sets respectively, and then marking the points as Z1, Z2 and Z3 respectively according to the intervals; find out
The subscript i, j is a positive integer, v is a function of solving an absolute value by referring to a feature vector and fabs, and the precision is a double-precision floating point type;
according to the neighborhood curvature of the point cloud midpoint calculated by the K neighbor, respectively storing the points with the neighborhood curvatures larger or smaller than gamma,
the formula for gamma is
Gamma is a reference threshold value of the defined approximate characteristic point, and sigma is an adjusting factor;
and S3, optimizing and calculating the original data of the geometric figure and the attribute information of the geometric figure, obtaining a BIM lightweight advanced processing file for format conversion, and meeting the display requirements of users.
2. The BIM-based lightweight advanced treatment work method according to claim 1, wherein the S1 includes:
s1-1, adopting a modeling kernel with a three-dimensional geometric modeling component ACIS and a 3D solid modeling component Parasolidd for BIM original geometric primitives, acquiring discrete data and organizing a data structure through an application program interface API; the data structure is adaptive to different versions, Business logic function Interface Business Interface interfaces are defined, working modules of different versions inherit and realize the Business Interface interfaces, and corresponding working modules are instantiated according to different versions through an internal matching method;
s1-2, dividing the geometric data into point sets and point indexes forming a patch;
s1-3, if the obtained patch is not a triangular patch, splitting the existing data and remapping the point index, otherwise, directly storing the point set and the index data of the patch;
a multi-face grid composed of mixed patches, n-edge patches with different edge numbers, wherein n is more than 3, n is the edge number, and there is a vertex set (pt)1、pt2、pt3……ptn) To find out
And
and vector angles, and reorganizing the main index data structure of the patch from small to large according to the magnitude of the vector angles: {3, 0, 1, 2 … … 3, 15, 17, 20 … … 3, n-3, n-2, n-1}, 3 denotes a triangular patch, followed by three numbers indicating the indices whose vertices are in the set of principal points;
and (3) carrying out grid vector distribution adjustment on the data so as to ensure the consistency of the front side and the back side:
A. the vectors are distributed according to each patch forming the grid, and then the original data is directly adopted; for the mesh subjected to splitting processing, vector data is associated to each new triangular patch;
B. the vectors are distributed according to each surface of the grid, if the number of the grid point sets is greater than the number of the vector distribution, the vectors at the last position of the vector set are adopted for completion, otherwise, if the number of the grid point sets is less than the number of the vector distribution, the rear-end vectors are directly abandoned, and if the number of the grid point sets is equal to the number of the vector distribution, the original data are directly adopted;
s1-4, calculating two-dimensional horizontal and vertical coordinate system UV information of the grid patch;
s1-5, extracting material information attached to the geometric surface, and analyzing the material information, including color, illumination and texture pictures;
s1-6, dispersing a NURBS curved surface (a non-uniform rational B spline surface), and setting parameters of a precision range, a pitch and a vector angle, so as to control the appearance of the NURBS curved surface to avoid distortion;
s1-7, the storage mode and the structure type of the BIM attribute information have diversity, so that the attribute extraction needs to be respectively processed according to different conditions;
aiming at the difference of storage modes and structure types, a label data processing module, a link data processing module and an extended attribute XAttributes processing module are respectively created, and after data are extracted by each module, the data are associated with geometric primitives and model tree nodes according to unique identifiers;
and S1-8, for the diversity of data types, extracting the attributes and methods of the data types by adopting a net reflection mechanism, and finally converting the finally obtained value information into character string types and outputting the character string types.
3. The BIM-based lightweight advanced treatment work method according to claim 1, wherein the S3 includes:
s3-1, the control formula of the triangle B spline curve type of any topology is as follows:
the determinant function of the point distance formula d (·.,..,.) verifies the linear combination of the control points; judging according to the series to obtain a triangular B spline curve control point set of the complex model curved surface; c represents a control point; t represents the proximity point around the control point, β is used to mark points at different positions in the linear group;
s3-2, processing of different grid patterns:
optimizing a grid data conversion grid into a triangular patch, wherein the grid has a multi-surface grid Polyface, and n is more than 4; triangle Grid, n is 3; the method comprises the following steps that a Quad mesh Quad Grid and 3 logically formed vertexes are an array of a row, each row represents a tri-edge mesh Triangle List, 4 logically formed vertexes are an array of a row, each row represents a Quad mesh Quad List, and due to the fact that the expression forms are inconsistent and the data organization modes are different, a program can deal with the situation of changeable styles by combining the program structure with the design mode, self-adaptive respective processing is achieved, and a unified data format is finally output;
s3-3, dividing the face slice into minimum units:
according to the point set and the indexes of the points forming the surface in the point set, remapping the points according to the rule of a triangular surface patch to obtain the main index data of a new surface patch;
s3-4, attribute:
due to the diversity of formats, the association relation between the attributes and the geometric primitives is not uniform; and after all the attributes are taken out in a self-adaptive manner through the corresponding module, writing the attributes into a sqlite lightweight database of the relational database management system, creating a corresponding table, and setting related main keys in the table, so that the association between the geometric primitives and the attributes is facilitated during later-period display.
4. The BIM-based lightweight advanced treatment work method according to claim 1, wherein the S3 further comprises:
layering the three-dimensional model into a group of horizontal contour lines, filling the contour line regions in various modes to form thin layers, and superposing the thin layers in the height direction to generate a physical model; one triangular mesh in the scattered triangular set after model discretization always has three edges shared by only three other adjacent triangles; searching a group of triangles intersected with a certain horizontal section plane from the scattered triangle set in sequence, and respectively calculating the section lines of the triangles to form one or more closed polygons;
the triangular edge is represented as: three z-coordinate values of a triangle are zmax，zminAnd zmidThere are three distributions: the z values of the three vertexes are different from each other; there are two vertices of maximum z-value; there are two minimum z-value vertices; the correlation formula used is:
5. the BIM-based lightweight advanced treatment work method according to claim 1, further comprising:
the sampling mode in the S1 is to selectively sample mountain peaks, pits, bottlenecks and boundary characteristic points; and the light weight effect is achieved through special treatment on the regular grid model, the contour line model and the irregular triangular net model.
6. The BIM-based lightweight advanced processing method as claimed in claim 1, wherein the lightweight file is a suffix-3 gd-format lightweight model file.
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