CN107633555A - The mutual cutting method of curved surface collection and system based on spacescan - Google Patents

Abstract

The invention discloses a method and system for realizing mutual cutting of curved surface sets based on space scanning. The method and system provide users with a technology for efficiently processing a large number of curved surface mutual cutting, and can complete triangle intersection detection, Multiple links such as memory scheduling, re-triangulation, and result surface patch generation can overcome inconsistencies such as multi-surface co-point, collinear, co-planar, and self-intersection in pairwise cutting calculations; through streaming loading, maintenance, and scanning Triangles intersecting planes, producing and storing completed surface patches as soon as possible and releasing the memory occupied by them can reduce the amount of data involved in the calculation and reduce the scale of calculation; the calculation of each step in the cutting process no longer depends on all the data of the previous step After processing, each step can be completed in parallel, which is especially suitable for high-performance computing environments.

Description

Method and system for mutual cutting of surface sets based on space scanning

technical field

The invention relates to a three-dimensional curved surface cutting technology, in particular, a method and system for realizing mutual cutting of curved surface sets based on space scanning.

Background technique

With the development of surveying and mapping technology and 3D modeling technology, people gradually have the conditions to construct various complex and fine 3D object models. The construction of these three-dimensional surface object models often involves cutting a large number of three-dimensional surfaces, and then eliminating redundant parts and kneading different surfaces into a whole. Generally, the idea of completing the mutual cutting of three-dimensional surfaces is: construct a separate index for each surface, and then perform intersection calculations in pairs. During the calculation process, the index is used to accelerate the triangle collision detection, and the intersection line is traced from a detected intersection position to complete. Cut calculation. But the above method also has the following problems:

(1) Cutting calculations are performed in pairs, and inconsistencies are likely to occur when multiple surfaces pass through and intersect at the same point in space;

(2) If a triangular patch intersects multiple surfaces, the triangular patch will undergo multiple re-triangulation through multiple rounds of pairwise cutting, and the triangulation process is affected by the cutting order, which may result in a non-globally optimal solution ;

(3) It is difficult to find the self-intersection phenomenon existing in the same surface by only judging the intersection of triangular patches from different surfaces;

(4) N three-dimensional surfaces need to perform N*(N-1)/2 pairwise cutting calculations, and the calculation scale may become very large;

(5) The generation of the result patch needs to be completed at the end of the pairwise intersection process. Only at this time can it be guaranteed that all intersecting triangles have been processed. When the data volume of a single surface is large, a large amount of memory will be consumed;

(6) Although pairwise cutting calculations between a large number of surfaces can be used as a basic computing unit to support parallel calculations, the surface data structure needs to support parallel operations. When the same surface is processed in parallel, it is necessary to coordinate the consistency relationship in the cutting process. However, each parallel unit corresponds to a complete cutting process, and consistency maintenance is quite difficult.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method and system for realizing mutual cutting of curved surface sets based on space scanning, especially for a large number of scattered three-dimensional Method and system for realizing mutual cutting of curved surfaces.

According to one aspect of the present invention, in order to solve the technical problem, the present invention provides a method for mutual cutting of curved surface sets based on space scanning, which includes the following steps:

Dynamically load the memory in sequence for the surface sets participating in the cutting;

Establish a two-dimensional dynamic spatial index to maintain the triangle information currently intersected with the scan plane;

Establish a priority queue to manage the upper V-shaped vertices along the scanning forward direction in the surface boundary;

Deal with the update and adjustment of the spatial index structure caused by scanning the V-shaped vertices;

Deal with the update and adjustment of the spatial index structure caused by scanning the intermediate vertices of the triangle;

Handle the update and adjustment of the spatial index structure caused by scanning the end vertices of the triangle;

Process the scan to complete the re-triangulation of the triangle;

Process the generation, growth, branching, merging and termination of the resulting surface patches;

Among them, the so-called upper V-shaped vertex refers to the boundary vertex on the boundary of the curved surface that satisfies the following conditions: the spatial order of the two adjacent vertices of the boundary vertex is greater than the spatial order of the boundary vertex, and any triangle connecting the boundary vertex The spatial sorting of any point is larger than the spatial sorting of the boundary vertices; the spatial sorting is reflected by the order in the priority queue, and the order in the priority queue is designed according to the order from the dimension where the scanning direction is located to any other dimension , and are sorted lexicographically for the spatial coordinates of the points.

In the surface set mutual cutting method of the present invention, the sequential dynamic loading of memory for the surface set is performed in the following manner:

Calculate the space occupied by the surfaces participating in the calculation in each dimension, and sort them according to the dimension with the largest extension. Only when the space scanning plane starts to intersect with a surface, the surface is dispatched to the memory. The above sorting order is exactly the scanning space The order in which the plane intersects the surfaces, so that the surfaces can be loaded sequentially during the scan in that order.

In the surface set mutual cutting method of the present invention, the two-dimensional dynamic spatial index structures used to maintain the triangle information currently intersected with the scanning plane are R tree spatial index, R+ tree spatial index, R* tree spatial index and quadtree space any of the indexes.

In the surface set mutual cutting method of the present invention, the triangle information maintained in the two-dimensional dynamic spatial index includes: the source surface of the triangle, the adjacent triangle corresponding to the edge that does not intersect the scanning plane, and the adjacent triangle in the spatial index , the set of adjacent triangles corresponding to the sides that have completely passed the scanning plane, and the set of intersection lines detected within the triangles.

In the mutual cutting method of the curved surface set of the present invention, only when the scanning plane touches the curved surface for the first time, the upper V-shaped vertices along the scanning forward direction in the boundary of the curved surface are calculated.

In the mutual cutting method of surface sets of the present invention, the update and adjustment of the spatial index structure caused by scanning the V-shaped vertices are processed, specifically including:

According to the surface and topology associated with the upper V-shaped vertex, all triangles including the upper V-shaped vertex are obtained, and the source surface is set for each triangle. The first type of adjacent triangle is set as a triangle that is opposite to the side that does not intersect with the scanning plane. The second type of adjacent triangle is set to the triangle that is in the same spatial index and shares the boundary with the triangle, the third type of adjacent triangle is set to the triangle that is opposite to the edge that has completely passed the scanning plane, and the set of intersection lines detected in the triangle is set The result of computing intersections for each triangle with the triangles in the spatial index;

Filter irrelevant triangles through the spatial index itself in the process of triangle calculation intersection;

The process of calculating the intersection line of triangles specifically includes: by converting the triangle into a parametric equation, analyzing the solution and its boundary satisfying two triangle parametric equations at the same time to obtain the intersection at 1 point, the intersection at 1 line segment, the intersection at a triangle patch, the intersection at A quadrilateral face, intersecting with a pentagonal face, intersecting with a hexagonal face...;

The common surface patch with overlapping surfaces is regarded as a single result surface patch;

The calculation of the intersection line above will also update the triangle information already in the spatial index structure, as long as these triangles intersect with the new triangles to be added.

In the surface set mutual cutting method of the present invention, the update and adjustment of the spatial index structure caused by scanning the middle vertex of a certain triangle can be refined as follows:

The unprocessed triangles containing the intermediate vertices of a certain triangle are processed in the same way as the upper V-shaped vertices, and these unprocessed triangles are added to the spatial index structure;

The construction of the adjacency relationship between triangles in the triangle information update process also needs to consider the processed triangle that contains the vertex: update the triangle information of the edge that has been scanned with the intermediate vertex of the triangle as the endpoint, and the adjacent The triangle is added to the set of adjacent triangles corresponding to the scanned edges.

In the surface set mutual cutting method of the present invention, the update and adjustment of the spatial index structure caused by scanning the end vertex of a certain triangle can be refined as follows:

Remove the scanned triangles from the spatial index structure;

The triangles adjacent to these removed triangles and in the spatial index update the adjacent triangle information corresponding to their scanned edges;

In the mutual cutting method of the surface set of the present invention, the re-triangulation of the completed triangle is performed in the following manner:

The intersection lines and triangle boundaries recorded in the triangle information are used as constraints for constrained triangulation;

For the above scanned original triangles, if one of its adjacent triangles is still in the spatial index, the new triangles constructed by triangulation are updated to the set of adjacent triangles corresponding to the scanned sides of these adjacent triangles.

In the mutual cutting method of surface sets of the present invention, the generation, growth, branching, merging and ending of processing result surface pieces can be refined as follows:

The resulting surface patch is generated: if the newly generated triangle does not have topological adjacency with the scanned triangle and the re-triangulated triangle, it marks the generation of a new surface patch;

Result surface patch growth: For the original triangle that has been scanned above, if its adjacent triangles have also been scanned, then starting from the common vertex with the adjacent triangle, all connected vertices that have been scanned are added to the vertex set of the result surface patch, all by The triangles formed by the above vertices are added to the result surface patch triangle set;

Branching of the result surface patch: If the result surface patch is broken into multiple disconnected parts along the scan plane at the growth boundary, it is necessary to process the branch and connect the differentiated multiple disconnected parts together through a linked list; each disconnected part may be called a growth point;

Result surface patch merging: each growing result surface patch independently maintains its vertex set and triangle set. If two or three result surface patches form a connected whole due to the completion of a certain triangle scan, you need Merge the vertex sets and triangle sets of two or three resulting surface patches, and update the vertex indices in the triangle sets;

The end of the result surface patch: If a scanned triangle and its adjacent triangles are also scanned, and there are no other differentiated growth points, the result surface patch will end processing and a complete result surface patch will be generated, which is also the final product of the algorithm. output; in order to improve memory utilization, the newly generated surface patch can be directly saved to the external storage or database, and at the same time release the memory occupied by the surface patch.

According to another aspect of the present invention, in order to solve the technical problem, the present invention also provides a system for mutual cutting of curved surface sets based on space scanning, including:

The memory dynamic loading unit is used to dynamically load the memory sequentially for the surface set participating in the cutting;

A spatial index establishment unit, configured to establish a two-dimensional dynamic spatial index to maintain current triangle information intersecting the scanning plane;

The priority queue building unit is used to build the upper V-shaped vertex along the scanning forward direction in the priority queue management surface boundary;

The upper V-shaped vertex processing unit is used to process the update and adjustment of the spatial index structure caused by scanning the upper V-shaped vertex;

The intermediate vertex processing unit is used to process the update and adjustment of the spatial index structure caused by scanning the intermediate vertex of the triangle;

The end vertex processing unit is used to process the update and adjustment of the spatial index structure caused by scanning the end vertex of the triangle;

A re-triangulation processing unit, configured to process the re-triangulation of the scanned triangles;

The surface patch processing unit is used to process the generation, growth, branching, merging and termination of the result surface patch;

Among them, the so-called upper V-shaped vertex refers to the boundary vertex on the boundary of the curved surface that satisfies the following conditions: the spatial order of the two adjacent vertices of the boundary vertex is greater than the spatial order of the boundary vertex, and any triangle connecting the boundary vertex The spatial sorting of any point is larger than the spatial sorting of the boundary vertices; the spatial sorting is reflected by the order in the priority queue, and the order in the priority queue is designed according to the order from the dimension where the scanning direction is located to any other dimension , and are sorted lexicographically for the spatial coordinates of the points.

Implementing the method and system for realizing mutual cutting of curved surface sets based on space scanning of the present invention has the following beneficial effects: the present invention provides users with a technology for efficiently processing a large number of curved surface mutual cutting, and can complete triangle intersection detection in a single scanning process , memory scheduling, re-triangulation, generation of result surface patches, etc., it can overcome inconsistencies such as multi-surface co-point, collinear, co-planar and self-intersection in pairwise cutting calculations; through stream loading, maintenance and Scan the triangles where the planes intersect, produce and store the completed surface as soon as possible and release the memory it occupies (scan while storing and releasing) and other methods to reduce the amount of data involved in the calculation and reduce the calculation scale; each step in the cutting process The calculation no longer depends on the completion of all data processing in the previous step, and each step can be completed in parallel, which is especially suitable for high-performance computing environments.

Description of drawings

The present invention will be further described below in conjunction with accompanying drawing and embodiment, in the accompanying drawing:

Fig. 1 is the functional block diagram of the mutual cutting system of curved surface sets based on the space scanning method of the present invention;

Fig. 2 is the schematic diagram of curved surface in the present invention;

Fig. 3 is a flow chart of the method for cutting current collection and mutual cutting of curved surfaces based on the space scanning method of the present invention.

detailed description

In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific implementation manners of the present invention will now be described in detail with reference to the accompanying drawings.

As shown in FIG. 1 , the surface set mutual cutting system based on the spatial scanning method of the present invention includes a surface loader 101, an upper V-shaped vertex priority queue 102, a spatial index 103, a surface patch growth list 104, and a result generator 105, wherein :

The surface loader 101 is used to receive from other surface modeling modules or read the existing surface data sets in the external memory, assuming that the y-axis direction is the spatial scanning direction, which is also the main sequence of the spatial sorting, and the x-axis is the spatial sorting The first sub-sequence when the z-axis is the second sub-sequence when the space is sorted. Spatial sorting linearly sorts the spatial points according to the main sequence-the first sub-sequence-the second sub-sequence. If the coordinates of the main sequence dimensions are different, they will be sorted according to the main sequence. Only when the main sequence coordinates are exactly the same, they will be sorted according to the first sub-order; if The coordinates on the first sub-sequence are also the same, then they are sorted according to the second sub-sequence; if the second sub-sequence is also the same, then they are the same coordinate points.

In order to avoid the equality judgment of floating-point numbers in spatial sorting, it is necessary to specify the data processing precision ε, which is the minimum step size during space scanning. The three-dimensional points in the cube are considered to have the same coordinate value, and the three-dimensional points in all the small cubes in the grid surface perpendicular to the main sequence have the same main sequence coordinates.

The above-mentioned surface loader 101 spatially sorts the minimum points sorted by space in each surface vertex set in the loaded surface data set, and obtains the surface scheduling sequence table L; if the input is the result data of the surface modeling module, or does not support external The memory randomly reads the surface, and the surface data set itself is cached in the external memory; the surface loader 101 schedules according to the intersection order of each surface and the spatial scanning plane, which is consistent with the order of the surfaces in the surface scheduling sequence table L, so through Whether the next surface needs to be loaded can be determined by judging the positional relationship between the first surface in the surface scheduling sequence table L and the scanning plane.

The surface loader 101 needs to calculate the boundary for each newly loaded surface, and output a list of upper V-shaped vertices therein, and the boundaries of the main curved surfaces include inner boundaries and outer boundaries. Assuming that the function Ord(V) obtains the spatial ordering of the vertex V, then the upper V-shaped vertex satisfies:

Ord(V)<Ord(Vprev) and Ord(V)<Ord(V _next ) and Ord(V)<Ord(P _any )

V _prev is the previous point of V on the surface boundary, and V _next is the next point. The vertices that are continuous and have the same sort number on the surface boundary should be merged into one; P _any is any point in the triangle with V as the vertex.

For the meaning of the upper V vertices, please refer to Figure 2. The surface in the figure is composed of triangles, and any two adjacent triangles have a common edge; any vertex belongs to 1 or more triangles. The upper V-shaped vertex is shown as the leftmost vertex 6 in the figure. When the scanning surface S scans to the position of this vertex 6, all the triangles associated with this vertex are on the right of S. Other vertices do not have this property, but have this property The boundary vertex of is the upper V vertex.

The upper V-shaped vertex priority queue 102 is used to receive the upper V-shaped vertices output by the surface loader 101. These upper V-shaped vertices are still sorted from small to large according to the space sorting order defined in the surface loader 101. The head of the queue is space The upper V-shaped vertex with the smallest sort, the tail of the queue is the upper V-shaped vertex with the largest spatial sort, you can choose a standard priority queue and redefine the sorting function; the order of elements in the upper V-shaped vertex priority queue 102 reflects the order of space scanning , the upper V-shaped vertices in the new surface loaded by the scanning process will be dynamically added to the appropriate position in this queue.

The spatial index 103 is used to receive the triangle associated with the head element (upper V-shaped vertex) of the upper V-shaped vertex priority queue 102, and maintain and assist in finding all triangles intersecting with the current scanning plane. Each index entry in the spatial index 103 includes: the source surface M of the triangle, the minimum enclosing rectangle R of the projection of the triangle on the scanning plane, the triangle JComing adjacent to the edge of the triangle that does not reach the scanning plane, and the triangle JOne adjacent to the edge intersecting the scanning plane and JTwo, the triangle set JPass adjacent to the edge that has passed the scanning plane, and the detected intersection line set SInter in the triangle.

In this specific implementation, the spatial index 103 is realized on the basis of the grid index, and its grid size adopts twice the longest side of the average triangle direction bounding box; each grid maintains a list of triangles intersecting with the grid, and the same An index entry information is shared across multiple grids.

The construction of the intersection line set Sinter is divided into two parts: one part is that when the triangle is added to the spatial index 103, it is obtained by querying other triangles that intersect with it and calculating the intersection line; the other part is when the subsequent triangle is added to the spatial index 103, due to the Triangles intersect to update the incoming intersection line. The intersection line obtained in the previous part will also be updated to the intersection line set Sinter of each intersecting triangle.

The surface patch growth linked list 104, each node of which represents a surface patch growth point, is used to receive the triangle that has just been scanned in the spatial index 103, and complete the link with the related elements of the linked list through the JPass set of the triangle, which is represented as a new structure The growth of the surface patch; through the JOne and JTwo information in the triangle, it can be traced back to the triangle adjacent to its other two sides, and its JPass and one of JOne and JTwo are updated; if the above-mentioned adjacent triangle has also completed the scan, it can be merged into Add them to the surface patch growth list 104 together.

If the triangles associated with JOne and JTwo of the triangles newly added to the surface patch growth list 104 are still in the spatial index 103, then the surface patch growth list 104 will add two nodes, one of which replaces the JPass node, describing two nodes respectively. The growth point corresponding to the edge is shown as a branch of the linked list 104; if JOne and JTwo are not associated with any triangle, then the node that originally described JPass needs to be removed from the linked list 104, which is shown as a linked list merge; if a surface patch grows linked list 104 nodes If it is empty, it means that the processing of the surface patch is completed, and all its constituent triangles are traced through the last deleted node, as the output of the surface patch growth list 104 .

The result generator 105 receives the triangle set output by the surface patch growth linked list 104, and forms a (vertex set, triangle set) data organization model suitable for storage, wherein each triangle in the triangle set is described by the index number of its vertex in the vertex set; the result The generator 105 is also responsible for calling back the output function for further processing or data storage.

The mutual cutting of curved surface sets based on space scanning in the present invention realizes that each component in the system is connected in series, the output of the previous component is the input of the latter component, and each component can generate output while receiving new input, Instead of waiting until all the data is entered, each component can work in parallel.

As shown in Fig. 3, the surface-collecting mutual cutting method based on the space scanning method of the present invention comprises the following steps:

Step 201 : Calculating the minimum points of spatial sorting in each surface vertex set; this step is completed by the surface loader 101 .

Step 202 : Spatially sort the set of minimum points in the previous step; this step is completed by the surface loader 101 .

Step 203: The scanning plane is moved forward to the plane determined by the first element L of the surface scheduling sequence table and the smaller point in the spatial order of the top element of the upper V-shaped vertex priority queue 102; this step is completed by the main control program.

Step 204: judging whether the scanning plane has scanned the first L element of the surface scheduling sequence table;

Step 205: Load the surface corresponding to the first L elements, calculate all its upper V-shaped vertices, and insert them into the priority queue 102; this step is completed by the surface loader 101.

Step 206: judging whether the head element of the priority queue 102 is an upper V-shaped vertex;

Step 207: Process the upper V-shaped vertex corresponding to the head element of the priority queue 102, and add all triangles containing the vertex to the spatial index 103; this step is completed by the main control function.

Step 208: judging whether the head element of the priority queue 102 is also an intermediate vertex of some triangles;

Step 209: process the triangle with the corresponding vertex of the head element of the priority queue 102 as the middle vertex, and establish an adjacency topology relationship between the triangles that share the edge on the side that has just finished scanning;

Step 210: determine whether the head element of the priority queue 102 is also the end vertex of some triangles; if not, there must be unprocessed triangles, and the scan must be continued;

Step 211: process the triangle with the corresponding vertex of the head element of the priority queue 102 as the end vertex, and establish the adjacency topology relationship among the triangles sharing the edge for the two edges that have just been scanned;

Step 212: Re-triangulate the triangle that completely passes through the scanning plane. At this time, the triangle already contains the intersection lines between other triangles that intersect with this triangle; these intersection lines and the original edges are used as constraints to perform constrained triangulation;

Step 213: Maintain the topological adjacency relationship between the triangles after re-triangulation. The establishment of these relationships is represented by the generation of patches in the scanning direction (the vertices with no associated triangles in the opposite direction of scanning), growth (full surrounding vertices), branching (the vertex with a defect in the scanning direction), merge (the vertex with a defect in the opposite direction of the scan), and end (the vertex with no associated triangle in the scanning direction); this step is completed by the surface patch growth list 104.

Step 214: Process the intersection relationship between all triangles newly added to the spatial index 101 and other triangles already in 101; the newly generated triangles include the part introduced by the upper V-shaped vertex, the intermediate vertex and the end vertex introduced by the topological relationship part; this step is completed by the main control function using the spatial index 103.

Step 215 : Generate a result surface, and convert the completely closed surface patch in the surface patch growth list 104 into a complete surface representation; this step is completed by the result generator 105 .

Embodiments of the present invention have been described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementations, and the above-mentioned specific implementations are only illustrative, rather than restrictive, and those of ordinary skill in the art will Under the enlightenment of the present invention, many forms can also be made without departing from the gist of the present invention and the protection scope of the claims, and these all belong to the protection of the present invention.

Claims (10)

1. a kind of mutual cutting method of curved surface collection based on spacescan, it is characterised in that comprise the following steps：

Curved surface collection dynamic load internal memory in order to participating in cutting；

Two-dimentional dynamically spatial-data index is established to safeguard the triangle information representing currently intersected with the plane of scanning motion；

The upper V-type summit for the edge scanning direction of advance established in priority query's management surface boundary；

Handle the renewal and adjustment of the space index structure triggered because scanning upper V-type summit；

Handle the renewal and adjustment of the space index structure triggered by the intermediate vertex for scanning triangle；

Handle the renewal and adjustment of the space index structure triggered by the end vertex for scanning triangle；

The trigonometric ratio again of triangle is completed in processing scanning；

Generation, growth, branch, merging and the end of result patch；

Wherein, so-called upper V-type summit refers to the border vertices for meeting following conditions on the border of curved surface：Two neighbours of border vertices The spatial classification for connecing summit is both greater than the spatial classification of the border vertices, and in any one triangle on fillet summit Any one point spatial classification it is all bigger than the spatial classification of the border vertices；The spatial classification passes through in priority query Order embody, the order in priority query is entered according to the order of dimension where scanning direction of advance to other any dimensions Row design, and to be sorted for the space coordinates lexcographical order of point.

2. the mutual cutting method of curved surface collection according to claim 1, it is characterised in that to curved surface collection dynamic load in order Internal memory is carried out in the following manner：

The space occupied in each dimension is calculated the curved surface for participating in calculating respectively, and is arranged according to the maximum dimension that extends Sequence, the curved surface is only just dispatched when spacescan plane starts to intersect with some curved surface to internal memory, and pressed in scanning process Each curved surface is sequentially loaded according to the sequence.

3. the mutual cutting method of curved surface collection according to claim 1, it is characterised in that for safeguarding currently and the plane of scanning motion The two-dimentional dynamically spatial-data index structure of intersecting triangle information representing is R tree space indexes, R+ tree space indexes, R* tree space indexes And any one in Quadtree Spatial Index.

4. the mutual cutting method of curved surface collection according to claim 1, it is characterised in that tieed up in two-dimentional dynamically spatial-data index The triangle information representing of shield includes：It is adjacent triangle corresponding to the source curved surface of the triangle, the side do not intersected with the plane of scanning motion, same Adjoining triangle in spatial index, completely by adjacent triangle sets corresponding to the side of the plane of scanning motion, triangle The intersection set detected.

5. the mutual cutting method of curved surface collection according to claim 4, it is characterised in that processing because scanning upper V-type summit and The renewal and adjustment of the space index structure of initiation, are specifically included：

The curved surface and topology situation associated according to V-type summit on this, obtains all triangles for including V-type summit on this, to every Individual triangle sets source curved surface, and first kind adjoining triangle is arranged to the relative triangle in the side do not intersected with the plane of scanning motion, Second class adjoining triangle is arranged to abut three with spatial index and with the triangle of the triangle Border, the 3rd class It is angular to be arranged to and completely by the relative triangle in the side of the plane of scanning motion, the intersection set detected in triangle is set Intersection acquired results are calculated for the triangle in each triangle and spatial index；

Triangle filters unrelated triangle by spatial index in itself during calculating intersection；

Triangle calculates intersection process and specifically included：By the way that triangle is converted into parametric equation, analysis meets two three simultaneously The solution of angular parametric equation and its border, which obtain, to intersect at 1 point, intersects at 1 line segment, intersect at a triangle surface, be intersecting In a quad patch, the situation for intersecting at a pentagon dough sheet, intersecting at a hexagon dough sheet ...；

The overlapping public patch of multiple curved surfaces is separately as a result patch；

The calculating of above-mentioned intersection can also update triangle information representing in space index structure simultaneously, if these triangles with New triangle to be added intersects.

6. the mutual cutting method of curved surface collection according to claim 1, it is characterised in that processing is because scanning some triangle Intermediate vertex and the renewal and adjustment of space index structure triggered, can be refined as：

The untreated triangle of intermediate vertex comprising some triangle and the processing method on upper V-type summit carry out processing phase Together, these untreated triangles are added into space index structure；

The structure of syntople also needs to consider to include the processed of the summit between triangle in triangle information representing renewal process Triangle：Triangle letter where the side for having completed scanning of the renewal using the intermediate vertex of some triangle as end points Breath, scanning side is completed in the triangle addition being adjacent and correspondingly abutted in triangle sets.

7. the mutual cutting method of curved surface collection according to claim 1, it is characterised in that processing is because scanning some triangle End vertex and the renewal and adjustment of space index structure triggered, can be refined as：

The triangle for completing scanning is removed out space index structure；

With the triangle of these removals adjacent and triangle in spatial index update its completed to scan side it is corresponding adjacent Connect triangle information representing.

8. the mutual cutting method of curved surface collection according to claim 1, it is characterised in that triangle is completed in the processing scanning Trigonometric ratio again carry out in the following manner：

Intersection and triangle border described in the triangle information representing, which are used as, to be constrained into row constraint trigonometric ratio；

To the former triangle of above-mentioned completion scanning, if its some adjoining triangles still in spatial index, trigonometric ratio structure The new triangle renewal built out has been completed scanning side to these adjoining triangles and correspondingly abutted in triangle sets.

9. the mutual cutting method of curved surface collection according to claim 1, it is characterised in that the generation of result patch, Growth, branch, merging and end, it can be refined as：

As a result patch produces：If triangle caused by new without and completed after the triangle and weight trigonometric ratio that scan three It is angular to have topological adjacency, then to indicate the generation of a new patch；

As a result patch grows：To the former triangle of above-mentioned completion scanning, also complete to scan if it abuts triangle, then Since with the adjoining triangle public vertex, all summits for being connected and having completed scanning add the vertex set of result patch Close, all triangles being made up of above-mentioned summit add result patch triangle sets；

As a result patch branch：If result patch is broken as multiple not connected components along the plane of scanning motion on growth border, Then need to handle branch, the multiple not connected components differentiated are cascaded by chained list；Each connected component can be with A referred to as growing point；

As a result patch merges：Each result patch grown safeguards alone its vertex set and triangle sets, Such as run into makes two or three result patch form an entirety of connection because some triangle scan is completed, then needs to close And the vertex set and triangle sets of two or three result patch, update the vertex index in triangle sets；

As a result patch terminates：If some completes the triangle of scanning, its adjoining triangle also all completes scanning, and it does not have The growing point of other differentiation, then the result dough sheet terminate to handle, produce a complete result patch, the result newly produced Patch can be saved directly in external memory or database, while discharges the internal memory that the patch occupies.

10. a kind of mutual diced system of curved surface collection based on spacescan, it is characterised in that include：

Internal memory dynamic load unit, for the curved surface collection dynamic load internal memory in order to participating in cutting；

Spatial index establishes unit, and the triangle currently intersected with the plane of scanning motion is safeguarded for establishing two-dimentional dynamically spatial-data index Information；

Priority query establishes unit, for establishing the upper V of the edge scanning direction of advance in priority query's management surface boundary Type summit；

Upper V-type vertex processing unit, for handling renewal and the tune of the space index structure triggered because scanning upper V-type summit It is whole；

Intermediate vertex processing unit, for handling the renewal of the space index structure triggered by the intermediate vertex for scanning triangle With adjustment；

End vertex processing unit, for handling the renewal of the space index structure triggered by the end vertex for scanning triangle With adjustment；

Again trigonometric ratio processing unit, the trigonometric ratio again for completing triangle is scanned for handling；

Patch processing unit, for the generation of result patch, growth, branch, merging and end；

Wherein, so-called upper V-type summit refers to the border vertices for meeting following conditions on the border of curved surface：Two neighbours of border vertices The spatial classification for connecing summit is both greater than the spatial classification of the border vertices, and in any one triangle on fillet summit Any one point spatial classification it is all bigger than the spatial classification of the border vertices；The spatial classification passes through in priority query Order embody, the order in priority query is entered according to the order of dimension where scanning direction of advance to other any dimensions Row design, and to be sorted for the space coordinates lexcographical order of point.