CN101488142B - Three-dimensional solid model retrieval method based on face topological interconnection constraint - Google Patents

Three-dimensional solid model retrieval method based on face topological interconnection constraint Download PDF

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CN101488142B
CN101488142B CN2008102438759A CN200810243875A CN101488142B CN 101488142 B CN101488142 B CN 101488142B CN 2008102438759 A CN2008102438759 A CN 2008102438759A CN 200810243875 A CN200810243875 A CN 200810243875A CN 101488142 B CN101488142 B CN 101488142B
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路通
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Abstract

The invention discloses a three-dimensional solid model retrieval method based on surface topology interconnection constraint. In the method, a model surface topology interconnection constraint set of the solid model comprising six kinds of surface relations of parallel, inclusion, coplanarity and L shape, T shape, X shape perpendicularity or intersection is firstly generated. Then, the commonestparallel surface pairs of the solid model are conflated to simplify the surface topology interconnection constraint set and generate a corresponding six conflated surface topology interconnection constraint set. When the three-dimensional solid model is retrieved, the approximation degree calculation of the surface topology interconnection constraint set is used for comparing the topology and geometric details. The three-dimensional solid model retrieval method based on the surface topology interconnection constraint has the beneficial effects that by rapid comparison of the surface topology interconnection constraints, similar three-dimensional solid models can be located rapidly in a large scale three-dimensional product database from two levels of overall topology relation and local topology/geometric details, thus multiplexing level of the three-dimensional product design is improved.

Description

Three-dimensional entity model search method based on the face topological interconnection constraint
Technical field
The present invention relates to a kind of three-dimensional entity model search method, and be particularly related to a kind of by six class face topologicals relations and make merger face topological interconnection constraint collection relatively the three-dimensional entity model method for quickly retrieving of parallel surface after on this basis merger based on the face topological interconnection constraint.
Background technology
In the past decade, along with the reduction of 3D graphic hardware cost and the maturation of technology, the three-dimensional CAD designing technique is rapidly developed and uses in various fields such as machinery, manufacturing, building, electronics, chemical industry, clothes and even advertisement.According to statistics, in recent years in the mould process industry 3D CAD modeling account for about 80%.
When the three-dimensional CAD solid model increased sharply on quantity and complicacy, three-dimensional objects data multiplexing problem progressively occurred.Generally speaking, the deviser on average spends the retrieval that working time of 60% is used for product information.Gunn points out further that then when carrying out new product designs, only about 20% from real innovation, and 40% can obtain from existing design, and other 40% can obtain on the basis of revising existing design.Ullman thinks, surpasses 75% new design and comprising multiplexing to design knowledge in the past.The multiplexing key issue that has become in the CAD field of product.3D shape retrieval (3D shape searching) is to solve the multiplexing effective way of three-dimensional objects.According to the definition of Kendall, the 3D shape retrieval is meant " calculating the degree of approximation between the 3D shape in the large-scale three dimensional model database ".The search mechanism of further investigation three-dimensional entity model must help lend some impetus to the in-depth of three-dimensional CAD technology and use, improves the automatization level of three-dimensional CAD design, accelerates the products innovation exploitation, has important significance for theories and actual application value.
Summary of the invention
Goal of the invention: the present invention is directed to the deficiencies in the prior art, a kind of three-dimensional entity model search method based on the face topological interconnection constraint is provided.
Technical scheme: the invention discloses a kind of three-dimensional entity model search method based on the face topological interconnection constraint, this method may further comprise the steps:
Step 1, the product model database of given three-dimensional entity model is imported three-dimensional entity model to be retrieved;
Step 2 judges whether to generate from the solid model to be retrieved of input the description document of its corresponding face topological interconnection constraint, if judged result is for being then to change step 12;
Step 3 is if the result of step 2, then reads geometric datas such as the summit, limit, face, ring of solid model for not;
Step 4, the bread that generates this solid model contains graph of a relation R IN, a node among this figure is corresponding to the face of a solid model, and a limit represents that its two model faces that connect have relation of inclusion;
Step 5 generates the coplanar relation figure R of this solid model I, a node among this figure is corresponding to the face of a solid model, and limit is represented two model face coplanes that it connects but is not had relation of inclusion;
Step 6 generates the face parallel relation figure R of this solid model P, a node among this figure is corresponding to the face of a solid model, and the parallel to each other but coplane and do not have relation of inclusion not of its two model faces that connect is represented on limit;
Step 7 generates the vertical or overlapping relation figure R of model face L type of this solid model L, a node among this figure is corresponding to the face of a solid model, and a limit represents that its two model faces that connect are the vertical or overlapping relation of L type;
Step 8 generates the vertical or overlapping relation figure R of model face T type of this solid model T, a node among this figure is corresponding to the face of a solid model, and a limit represents that its two model faces that connect are the vertical or overlapping relation of T type;
Step 9 generates the vertical or overlapping relation figure R of model face X type of this solid model X, a node among this figure is corresponding to the face of a solid model, and a limit represents that its two model faces that connect are the vertical or overlapping relation of X type; With model face topological interconnection constraint collection G TOPO={ R IN, R I, R P, R L, R T, R XWrite corresponding description document;
Step 10, traversal R PIn each node, two parallel surfaces overlapped ratio is maximum and that distance is minimum merge into one new for node;
Step 11 is if bread contains graph of a relation R IN, coplanar relation figure R I, model face L type is vertical or overlapping relation figure R L, model face T type is vertical or overlapping relation figure R T, model face X type is vertical or overlapping relation figure R XIn to comprise in the step 10 merged two parallel surfaces right, then from this graph of a relation, replace this two faces with the node of facing that step 10 was generated, and rebuild should be in the face of node and other internodal relation of inclusion, coplanar relation, the L type is vertical or overlapping relation, the T type is vertical or overlapping relation, the vertical or overlapping relation of X type, obtains the merger face topological interconnection constraint collection G ' after the merger TOPO=R ' IN, R ' I, R ' P, R ' L, R ' T, R ' X, and write corresponding description document;
Step 12 is got three-dimensional entity model and corresponding merger face topological interconnection constraint collection description document thereof in the product model database one by one;
Step 13, the merger face topological interconnection constraint collection of model in model more to be retrieved and the product model database, and calculate its degree of approximation;
Step 14, by face topological interconnection constraint collection degree of approximation comparative result after the merger, relatively its model face topological interconnection constraint collection compares with the part of making further geometric detail, improves the degree of accuracy of three-dimensional search;
Step 15 judges whether the product model database travels through end, if the result then changes step 12 for not;
Step 16 is if the judged result of step 15 is for being the back output of then each degree of approximation being sorted from big to small;
The degree of approximation after the ordering from big to small of step 17, output;
Whether step 18 is that " 1 " judges whether the model of being imported to be retrieved has added the product model database according to degree of approximation comparative result, if judged result is for being then to return step 1; Step 19 is if step 18 result then joins the solid model of being imported, corresponding model face topological interconnection constraint collection and merger face topological interconnection constraint collection description document the product model database, and returns step 1 for not.
Among the present invention, the three-dimensional entity model in three-dimensional entity model to be retrieved and the product model database should meet the STEP standard, but its coordinate system definition, solid model size, sense of rotation are had no special requirements.
Among the present invention, the face topological interconnection constraint is divided into two levels: by the model face topological interconnection constraint collection G of initial model face topological relationship analysis generation TOPO={ R IN, R I, R P, R L, R T, R X, and the merger face topological interconnection constraint collection G ' that generates after the node merger TOPO=R ' IN, R ' I, R ' P, R ' L, R ' T, R ' X;
Among the present invention, six class face graph of a relation R of composition model face topological interconnection constraint collection IN, R I, R P, R L, R T, R XIn, node corresponding to certain model face, limit corresponding to certain topological relation; The geometric properties of model face (as normal vector, area, shape etc.) is then listed as the attribute of node in the face graph of a relation, and the geometric detail when making three-dimensional search relatively or local retrieval.
Among the present invention, form six class merger face graph of a relation R ' of merger face topological interconnection constraint collection IN, R ' I, R ' P, R ' L, R ' T, R ' XIn, node corresponding to one meet the overlapping ratio maximum in mutual projecting plane, simultaneously the minimum parallel surface of distance is right, a kind of corresponding in the six class topological relations of limit.
Among the present invention, the pairing merger face topological of certain three-dimensional entity model interconnection constraint collection description document is defined by XML.
Among the present invention, the pairing model face topological of certain three-dimensional entity model interconnection constraint collection description document is defined by XML.
Among the present invention, the method for calculating two solid model degrees of approximation according to the interconnection constraint of merger face topological is:
Similarity(M，N)＝Similar(R’ P(M)，R’ P(N)/6+Similar(R’ L(M)，R’ L(N))/6
+Similar(R’ IN(M)，R’ IN(N))/6+Similar(R’ I(M)，R’ I(N))/6
+Similar(R’ T(M)，R’ T(N))/6+Similar(R’ XM)，R’ XN))/6
Wherein, M, N represent two solid models, Similar (R 1, R 2) for calculating the existing function of two figure maximum match degree; The span of Similarity () function is [0,100%].
Among the present invention, further the local comparative approach of geometric detail is that the face geometric attribute of getting in the six class model face graphs of a relation is made comparisons; Wherein the face geometric attribute comprises the quantity of the girth of normal vector, face of type, the face of face and area, face inner edge.
Among the present invention, judge that the method whether model to be retrieved has added the product model database is: check whether have with model approximation degree to be retrieved be that 100% model exists, if judged result for being, then adds in the product model database, otherwise not adding.
Beneficial effect: the inventive method is expressed and product exchange correlation iso standard STEP (Standard for the Exchange of Product Information)/IGES (Initial Graphics ExchangeStandard) from cad data, on the most main flow cad model of compatibility describing mode basis, extract, analyzing three-dimensional solid model geometric configuration describes, generate respectively by comprise, parallel, coplane, the L type is vertical or intersect, the T type is vertical or intersect, the X type is vertical or the totally six class faces relation of intersecting is formed model face topological interconnection constraint collection; On this basis to the parallel surface that meets overlapping ratio of projection and distance restraint to doing merger, generate merger face topological interconnection constraint collection.When the retrieval three-dimensional entity model, be starting point relatively with merger face topological interconnection constraint collection, the degree of approximation between rapid calculation model; And can further compare attributes such as Noodles type, normal vector, limit number according to the difference of overall topological constraints, make further geometric detail and distinguish.
Because at present in the three-dimensional design field, surpass 75% new design and comprising multiplexing to design knowledge in the past, and the deviser on average need spend working time of 60% and is used for the retrieval of product in the past.Therefore, quick comparison by the face topological interconnection constraint, can be from overall topological relation and two levels of local topology/geometric detail, in extensive Moulds Based on Three-Dimensional Models database, locate similar three-dimensional entity model fast, thereby improve multiplexing level, the quickening products innovation development ability of three-dimensional objects design, and help lend some impetus to three-dimensional CAD technology in-depth application.
Description of drawings
Below in conjunction with the drawings and specific embodiments the present invention is done further and to specify.
Fig. 1 represents workflow diagram of the present invention.
Fig. 2 is the example of a three-dimensional entity model.
Fig. 3 is the model face parallel relation figure R that generates from this three-dimensional entity model p
Fig. 4 is the vertical or overlapping relation figure R of model face L type that generates from this three-dimensional entity model L
Fig. 5 contains graph of a relation R for the model bread that generates from this three-dimensional entity model IN
Fig. 6 is R PThe example of middle node merger.
Fig. 7 generates merger face parallel relation figure R ' after the node merger p
Fig. 8 generates the vertical or overlapping relation figure R ' of merger face L type after the node merger L
Embodiment
As shown in Figure 1, the invention discloses a kind of three-dimensional entity model search method based on the face topological interconnection constraint, this method may further comprise the steps:
Step 1, the product model database of given three-dimensional entity model is imported three-dimensional entity model to be retrieved;
Step 2 judges whether to generate from the solid model to be retrieved of input the description document of its corresponding face topological interconnection constraint, if judged result is for being then to change step 12;
Step 3 is if the result of step 2, then reads geometric datas such as the summit, limit, face, ring of solid model for not;
Step 4, the bread that generates this solid model contains graph of a relation R IN, a node among this figure is corresponding to the face of a solid model, and a limit represents that its two model faces that connect have relation of inclusion;
Step 5 generates the coplanar relation figure R of this solid model I, a node among this figure is corresponding to the face of a solid model, and limit is represented two model face coplanes that it connects but is not had relation of inclusion;
Step 6 generates the face parallel relation figure R of this solid model P, a node among this figure is corresponding to the face of a solid model, and the parallel to each other but coplane and do not have relation of inclusion not of its two model faces that connect is represented on limit;
Step 7 generates the vertical or overlapping relation figure R of model face L type of this solid model L, a node among this figure is corresponding to the face of a solid model, and a limit represents that its two model faces that connect are the vertical or overlapping relation of L type;
Step 8 generates the vertical or overlapping relation figure R of model face T type of this solid model T, a node among this figure is corresponding to the face of a solid model, and a limit represents that its two model faces that connect are the vertical or overlapping relation of T type;
Step 9 generates the vertical or overlapping relation figure R of model face X type of this solid model X, a node among this figure is corresponding to the face of a solid model, and a limit represents that its two model faces that connect are the vertical or overlapping relation of X type; With model face topological interconnection constraint collection G TOPO={ R IN, R I, R P, R L, R T, R XWrite corresponding description document;
Step 10, traversal R PIn each node, two parallel surfaces overlapped ratio is maximum and that distance is minimum merge into one new for node;
Step 11 is if bread contains graph of a relation R IN, coplanar relation figure R I, model face L type is vertical or overlapping relation figure R L, model face T type is vertical or overlapping relation figure R T, model face X type is vertical or overlapping relation figure R XIn to comprise in the step 10 merged two parallel surfaces right, then from this graph of a relation, replace this two faces with the node of facing that step 10 was generated, and rebuild should be in the face of node and other internodal relation of inclusion, coplanar relation, the L type is vertical or overlapping relation, the T type is vertical or overlapping relation, the vertical or overlapping relation of X type, obtains the merger face topological interconnection constraint collection G ' after the merger TOPO=P ' IN, R ' I, R ' P, R ' L, R ' T, R ' X, and write corresponding description document;
Step 12 is got three-dimensional entity model and corresponding merger face topological interconnection constraint collection description document thereof in the product model database one by one;
Step 13, the merger face topological interconnection constraint collection of model in model more to be retrieved and the product model database, and calculate its degree of approximation;
Step 14, by face topological interconnection constraint collection degree of approximation comparative result after the merger, relatively its model face topological interconnection constraint collection compares with the part of making further geometric detail, improves the degree of accuracy of three-dimensional search;
Step 15 judges whether the product model database travels through end, if the result then changes step 12 for not;
Step 16 is if the judged result of step 15 is for being the back output of then each degree of approximation being sorted from big to small;
Step 17 is returned this result for retrieval;
Whether step 18 is that " 1 " judges whether the model of being imported to be retrieved has added the product model database according to degree of approximation comparative result, if judged result is for being then to return step 1;
Step 19 is if step 18 result then joins the solid model of being imported, corresponding model face topological interconnection constraint collection and merger face topological interconnection constraint collection description document the product model database, and returns step 1 for not.
More particularly, the initial solid model of importing of the step 1 among Fig. 1 is by the STEP formal definition, and solid model size, direction, angle are not had specific (special) requirements.
Step 4-step 9 generates six class face graph of a relation R after reading the model geometric data IN, R I, R P, R L, R TAnd R X, concrete steps are: 1) travel through each model face A, get other arbitrary model face B in the solid model, if meet following six class face topological restriction relations, then model A and model face B are added corresponding face graph of a relation as node, and connect with a limit:
1 ) , R IN ( A , B ) = { ∀ a ∈ A , a ∈ B } ;
Figure GSB00000126030900062
Figure GSB00000126030900063
Figure GSB00000126030900064
Figure GSB00000126030900065
Figure GSB00000126030900066
Figure GSB00000126030900067
In the CAD solid model example that Fig. 2 provides, if definition R IN(A)={ B:r In(A, B) }, then the model face topological interconnection constraint collection of Fig. 1 can be described below:
R P(F 1)＝{F 3}，R P(F 2)＝{F 4}，
R P(F 3)＝{F 1}，R P(F 4)＝{F 2}，
R L(F 1)＝R L(F 3)＝{F 2，F 4，F 5，F 6}，
R L(F 2)＝R L(F 4)＝{F 1，F 3，F 5，F 6}，
R IN(F 5)＝{F 7，F 9}，R P(F 5)＝{F 6，F 8，F 10}，
R L(F 5)＝R L(F 6)＝{F 1，F 2，F 3，F 4}，
R IN(F 6)＝{F 8，F 10}，R P(F 6)＝{F 5，F 7，F 9}，
R P(F 7)＝{F 8，F 9，F 10}，R P(F 8)＝{F 7，F 9，F 10}，
R P(F 9)＝{F 7，F 8，F 10}，R P(F 10)＝{F 7，F 8，F 9}
Fig. 3 is the model face parallel relation figure R corresponding to three-dimensional entity model shown in Figure 2 p, Fig. 4 is the vertical or overlapping relation figure R of model face L type that generates from this three-dimensional entity model L, and Fig. 5 contains graph of a relation R for the model bread that generates from this three-dimensional entity model INNothing satisfies coplane in this solid model, the T type is vertical or intersect, the X type is vertical or the model face of overlapping relation, so R I, R TAnd R XBe sky.
Step 10 pair meets the parallel surface of overlapping ratio of projection and distance to carrying out merger, generates the face parallel relation figure R ' after the merger PR ' PThe generation step is as follows:
(1) traversal R PTu Gebian.If when the front is e i, get e iTwo node f that connect I1And f I2, order
d(f i1，f i2)＝area(overlap(f i1，f i2))/min(area(f i1)，area(f i2))
Calculate d (f I1, f I2) and it is added ingress f respectively by ascending order I1And f I2Face distance set (area (f wherein i) be area, overlap (f i, f j) be faying surface);
(2) traversal R PScheme each node.If present node is f iGet f iIdentity distance is from the pairing set of node S of concentrated maximal value (f i), select wherein certain node f by following priority ranking jGenerating the candidate faces＜f i, f j;
Figure GSB00000126030900071
b ) , ∀ f k ∈ S ( f i ) , ∀ f j ∈ S ( f i ) , dis(f i，f j)≤dis(f i，f k)
Dis (f wherein i, f j) be identity distance from;
(3) candidate of traversal (2) generation is in the face of collection, as follows to R PThe figure merger obtains corresponding face topology associated diagram R ' P(R ' PBe initially sky):
A) duplicate R PAll nodes among the figure are to R ' PFigure;
B) traversal R PIn all limits, if its connected node f iAnd f kBelong to the candidate in the face of collection, then merge f iAnd f kObtain new node PF (f i, f k), with PF (f i, f k) adding R ' PFigure;
C) traversal R ' PEach node among the figure is established and is had certain node PF j(f J1, f J2), if f J1, f i, f J2With f iBetween at former R PThere is the limit to connect among the figure, then at R ' PAmong the figure at node PF j(f J1, f J2) and PF (f i, f k) between add a limit;
(4) traversal R ' PIn each node, calculate its largest connected subgraph R ' Pmax, with R ' PmaxNormal direction is as model principal direction.
Wherein, (1), (2) generate the candidate in the face of collection, and (3) face set pair R with the candidate PMerger obtains R ' P(4) calculate largest connected subgraph to determine model principal direction.Fig. 6 has provided corresponding to R shown in Figure 3 PThe process of middle node merger, its merger is R ' as a result PIn Fig. 7, show.
Step 11 is at R ' PAfter the generation,, recomputate R respectively in conjunction with merge node related in this process L, R In, R I, R T, R X, to generate R ' L, R ' In, R ' I, R ' T, R ' XR ' wherein LGenerating algorithm is as follows:
(1) R ' LPut sky;
(2) traversal R LEach node.If present node is f iTraversal node f iIf each limit is at R LTwo limit (f of middle existence i, f j) and (f i, f k) (j ≠ k), and f jAnd f kAt R ' PThe middle merging, then:
A) at R ' LThe middle new node VF (f that adds j, f k);
B) if f iNot at R ' LAmong the figure:
If i is f iCan't merge with any existing node, then add new node VF (f i, ^);
Ii otherwise if f iCan with R ' LNode VF (f among the figure m, ^) merging (can constitute R ' PMiddle merge node), be merged into new node VF (f m, f i);
C) otherwise f iBe present in R ' LAmong the figure, return;
D) at R ' LAdd fillet between above-mentioned two corresponding node among the figure;
Fig. 8 has provided corresponding to the R ' after the merger of Fig. 4 LFigure.R ' In, R ' I, R ' T, R ' XCan generate by similar approach.
Step 16-18 relatively solid model also presses degree of approximation ordering back output.If Similar (A B) calculates two existing functions of scheming the degree of approximation of A and B for being used to, and then three-dimensional entity model degree of approximation computing method are:
Similarity(M，N)＝Similar(R’ P(M)，R’ P(N)/6+Similar(R’ L(M)，R’ L(N))/6
+Similar(R’ IN(M)，R’ IN(N))/6+Similar(R’ I(M)，R’ I(N))/6
+Similar(R’ T(M)，R’ T(N))/6+Similar(R’ XM)，R’ XN))/6
Wherein M, N are any two solid models.With each model in the solid model imported and the product model database one by one relatively and after calculating the degree of approximation, by the ordering one by one from big to small of degree of approximation value, with corresponding model output.
The invention provides a kind of three-dimensional entity model search method based on the face topological interconnection constraint; the method and the approach of this technical scheme of specific implementation are a lot; the above only is a preferred implementation of the present invention; should be understood that; for those skilled in the art; under the prerequisite that does not break away from the principle of the invention, can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.The all available prior art of each component part not clear and definite in the present embodiment is realized.

Claims (10)

1. three-dimensional entity model search method based on the face topological interconnection constraint is characterized in that this method may further comprise the steps:
(1) the product model database of given three-dimensional entity model is imported three-dimensional entity model to be retrieved;
(2) judge whether to generate the description document of its corresponding face topological interconnection constraint,, otherwise carry out next step if judged result is for being then to skip to step (12) from the solid model to be retrieved of input; The description document of described face topological interconnection constraint is the merger face topological interconnection constraint collection G ' that comprises after the merger TOPO=R ' IN, R ' I, R ' P, R ' L, R ' T, R ' XDescription document;
(3) read the solid model geometric data;
(4) bread that generates this solid model contains graph of a relation R IN, a node among this figure is corresponding to the face of a solid model, and a limit represents that its two model faces that connect have relation of inclusion;
(5) generate the coplanar relation figure R of this solid model I, a node among this figure is corresponding to the face of a solid model, and limit is represented two model face coplanes that it connects but is not had relation of inclusion;
(6) generate the face parallel relation figure R of this solid model P, a node among this figure is corresponding to the face of a solid model, and the parallel to each other but coplane and do not have relation of inclusion not of its two model faces that connect is represented on limit;
(7) generate the vertical or overlapping relation figure R of model face L type of this solid model L, a node among this figure is corresponding to the face of a solid model, and a limit represents that its two model faces that connect are the vertical or overlapping relation of L type;
(8) generate the vertical or overlapping relation figure R of model face T type of this solid model T, a node among this figure is corresponding to the face of a solid model, and a limit represents that its two model faces that connect are the vertical or overlapping relation of T type;
(9) generate the vertical or overlapping relation figure R of model face X type of this solid model X, a node among this figure is corresponding to the face of a solid model, and a limit represents that its two model faces that connect are the vertical or overlapping relation of X type; With model face topological interconnection constraint collection G TOPO={ R IN, R I, R P, R L, R T, R XWrite corresponding description document;
(10) traversal R PIn each node, two parallel surfaces overlapped ratio is maximum and that distance is minimum merge into one new for node;
(11) if bread contains graph of a relation R IN, coplanar relation figure R I, model face L type is vertical or overlapping relation figure R L, model face T type is vertical or overlapping relation figure R T, model face X type is vertical or overlapping relation figure R XIn to comprise in the step (10) merged two parallel surfaces right, then the node of facing that is generated with step (10) from this graph of a relation replaces this two faces, and rebuild should be in the face of node and other internodal relation of inclusion, coplanar relation, the L type is vertical or overlapping relation, the T type is vertical or overlapping relation, the vertical or overlapping relation of X type, obtains the merger face topological interconnection constraint collection G ' after the merger TOPO=R ' IN, R ' I, R ' P, R ' L, R ' T, R ' X, and write corresponding description document;
(12) get three-dimensional entity model in the product model database and corresponding merger face topological interconnection constraint collection description document thereof one by one;
(13) the merger face topological interconnection constraint collection of model in model more to be retrieved and the product model database, and calculate its degree of approximation;
(14), compare its model face topological interconnection constraint collection by face topological interconnection constraint collection degree of approximation comparative result after the merger;
(15) judge whether the product model database travels through end, if the result then changes step (12), otherwise carries out next step for not;
(16) each degree of approximation is sorted from big to small back output;
(17) degree of approximation after the output ordering from big to small;
(18) whether be that " 1 " judges whether the model of being imported to be retrieved has added the product model database according to degree of approximation comparative result, if judged result is for being then to return step (1), otherwise carry out next step;
(19) solid model of being imported, corresponding model face topological interconnection constraint collection and merger face topological interconnection constraint collection description document are joined the product model database, and return step (1).
2. geometric data comprises summit, limit, face, the ring of solid model in the three-dimensional entity model search method based on the face topological interconnection constraint as claimed in claim 1, step (3).
3. the three-dimensional entity model search method based on the face topological interconnection constraint as claimed in claim 1, wherein the face topological interconnection constraint is divided into two levels: by the model face topological interconnection constraint collection G of initial model face topological relationship analysis generation TOPO={ R IN, R I, R P, R L, R T, R X, and the merger face topological interconnection constraint collection G ' that generates after the node merger TOPO=R ' IN, R ' I, R ' P, R ' L, R ' T, R ' X.
4. the three-dimensional entity model search method based on the face topological interconnection constraint as claimed in claim 1, wherein six class face graph of a relation R of composition model face topological interconnection constraint collection IN, R I, R P, R L, R T, R XIn, node corresponding to a kind of model face, limit corresponding to a kind of topological relation; The geometric properties of model face is listed as the attribute of node in the face graph of a relation.
5. the three-dimensional entity model search method based on the face topological interconnection constraint as claimed in claim 1 is wherein formed six class merger face graph of a relation R ' of merger face topological interconnection constraint collection IN, R ' I, R ' P, R ' L, R ' T, R ' XIn, node corresponding to one meet the overlapping ratio maximum in mutual projecting plane, simultaneously the minimum parallel surface of distance is right, a kind of corresponding in the six class topological relations of limit.
6. the three-dimensional entity model search method based on the face topological interconnection constraint as claimed in claim 1, wherein the pairing merger face topological of three-dimensional entity model interconnection constraint collection description document is defined by XML.
7. the three-dimensional entity model search method based on the face topological interconnection constraint as claimed in claim 1, wherein the pairing model face topological of three-dimensional entity model interconnection constraint collection description document is defined by XML.
8. the three-dimensional entity model search method based on the face topological interconnection constraint as claimed in claim 1, wherein the method according to two solid model degrees of approximation of merger face topological interconnection constraint calculating is:
Similarity(M，N)＝Similar(R’ P(M)，R’ P(N)/6+Similar(R’ L(M)，R’ L(N))/6
+Similar(R’ IN(M)，R’ IN(N))/6+Similar(R’ I(M)，R’ I(N))/6
+Similar(R’ T(M)，R’ T(N))/6+Similar(R’ xM)，R’ xN))/6
Wherein, M, N represent two solid models, Similar (R 1, R 2) for calculating the function of two figure maximum match degree; The span of Similarity () function is [0,100%].
9. the three-dimensional entity model search method based on the face topological interconnection constraint as claimed in claim 1, wherein compare its model face topological interconnection constraint collection in the step (14) and compare as the part of further geometric detail, concrete grammar is that the face geometric attribute of getting in the six class model face graphs of a relation is made comparisons; Wherein the face geometric attribute comprises the quantity of the girth of normal vector, face of type, the face of face and area, face inner edge.
10. the three-dimensional entity model search method based on the face topological interconnection constraint as claimed in claim 1, step (18) judges that the method whether model to be retrieved has added the product model database is: check whether have with model approximation degree to be retrieved be that 100% model exists, if judged result is for being, then add in the product model database, otherwise do not add.
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