Method and System for comparing 3D Models
A method is disclosed for indexing 3D digital models, retrieving them, comparing them and displaying the results in a 3D space. The method comprises four complementary parts, i.e. displaying, comparing/searching, reconciling the faces, and classifying the results. These parts can overlap with each other or can be implemented separately. A method is described for retrieving 3D models that share certain similarities of form with a reference 3D model, involving a first step of analysis in order to generate representations (descriptors). The process of searching/comparing 3D models based on descriptors partially related to the faces optionally requires a process of pairing and reconciling the faces. The results are displayed in a single 3-dimensional space and, owing to a mark on the faces of the 3D models, makes it possible to distinguish several types of difference between similar 3D models.
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21 ) A computer implemented method for comparing a reference 3D model with a plurality of 3D models, the computer implemented method comprising:
computing a confidence level according to similarities and differences of the geometrical characteristics between a descriptor of the reference 3D model and at least one descriptor of one of the plurality of 3D models, each descriptor comprising a plurality of characteristics associated with at least one face of the 3D model;
computing a similarity value using the computed confidence levels between the characteristics of a descriptor of the reference 3D model and the characteristics of at least one descriptor of one of the plurality of 3D models.
22 ) The computer implemented method of claim 21 , further comprising repositioning the plurality of 3D models according to the geometrical characteristics of the reference 3D model.
23 ) The computer implemented method of claim 22 , each descriptor further comprising:
geometrical characteristics that are dependent of a coordinate system; and
geometrical characteristics that are invariant of the coordinate system;
wherein the repositioning of the plurality of 3D models comprises:
pairing sub sets of the descriptor of the reference 3D model with sub sets of the at least one descriptor of one of the plurality of 3D models based on the invariant geometrical characteristics of the descriptor of the reference 3D model and on the invariant geometrical characteristics of at least one descriptor of one of the plurality of 3D models;
determining groups of transformations to reconcile the pairings using the dependent geometrical characteristics of the descriptor of the reference 3D model and the dependent geometrical characteristics of at least one descriptor of one of the plurality of 3D models;
identifying a first group of similar transformations from the groups of transformations.
24 ) The computer implemented method of claim 23 , the method further comprising:
computing a confidence level of each pairing according to similarities and differences between the invariant geometrical characteristics of the descriptor of the reference 3D model and the invariant geometrical characteristics of the descriptor of one of the plurality of 3D models.
25 ) The computer implemented method of claim 24 , the step of computing a similarity value using the first group of transformations to identify the similarities and differences.
26 ) The computer implemented method of claim 23 , the method further comprising:
computing a confidence level of each reconciled pair of sub sets of descriptors of the reference 3D models according to similarity of dependent geometrical characteristics of the descriptor of the reference 3D model and the descriptor of one of the plurality of 3D models.
27 ) The computer implemented method of claim 23 , the method further comprising the steps of:
identifying a second group of similar transformations from the groups of transformations;
computing a reconciliation confidence level using the second group of transformations;
identifying the similarities and differences between the reference 3D model and one or more 3D models from the plurality of 3D models using the first and second group of transformations; and
computing a combined similarity value based on the first and second groups of transformations.
28 ) The computer implemented method of claim 23 , wherein the geometrical characteristics that are invariant of the coordinate system comprise geometrical characteristics of at least one of: area, perimeter, and the geometrical characteristics that are dependant of the coordinate system comprise geometrical characteristics of at least one of: center of gravity and axes of moments of inertia.
29 ) The computer implemented method of claim 21 , wherein the descriptor further comprises G2 continuity geometrical characteristics related to a set of faces having G2 continuity.
30 ) The computer implemented method of claim 21 , in which a portion of the descriptor is used for the computation of the confidence level.
31 ) The computer implemented method of claim 21 , in which the descriptor is generated for at least a selected face of the reference 3D model.
32 ) The computer implemented method of claim 21 , in which the computation of the confidence level is affected by at least one constraint on one or a plurality of characteristics of a 3D model and/or between characteristics of a 3D model.
33 ) The computer implemented method of claim 32 , wherein the constraint is input by an operator.
34 ) A method to display results of comparison between a reference 3D model and more than two 3D models in the form of a view of a 3D space, which includes the 3D models, the method comprising:
applying criteria for selecting the 3D models to be displayed;
applying criteria for constraining spatial positioning of the 3D models;
applying criteria for constraining the marking of the 3D models;
displaying the 3D models resulting from the comparison, wherein only the 3D models meeting the applied criteria are displayed.
35 ) The method of claim 34 , wherein at least a portion of similarities or differences identified in the comparison between the reference 3D model and a plurality of 3D models is displayed.
36 ) The method of claim 35 , wherein a spatial arrangement and/or a marking of one or more 3D models from the plurality of 3D models represents one or a plurality of other information.
37 ) The method of claim 34 , the method further comprising displaying using marked faces the 3D models in comparison to the reference 3D model, each marking identifying the similarities and/or the differences between more than two 3D models.
38 ) The method of claim 34 , wherein the similarities and the differences are presented on sub sets of the 3D models.
39 ) A data processing system configured to achieve the process of comparing more than two 3D models for the purposes of searching for identical or similar 3D models, of determining the similarities and the differences, of classifying, of ranking, of ordering, of sorting, of filtering the 3D models using the method of any one of claims 21 to 33 .
40 ) A process for manufacturing a product, process characterized by the operation of a 3D model for manufacturing at least a part of the product, the 3D model being directly selected or modified from a selected 3D model using the method of comparison as claimed in one of claims 21 to 33 .