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Geometric Similarity

These procedures to the geometric search are known in the jargon as shape indexing, retrieval of geometric or 3D content retrieval. These procedures are all based on feature extraction from the 3D objects. The procedures differ however interpreted, which object types and body will be tested and evaluated with regard to your similarity. So procedures for evaluating differ from face shapes, sculptures and biological form elements of procedures for examining discrete geometric shapes and objects as they are used in an industrial environment.


3D data are prerequisites to the use of the procedures

Condition for the application of the shape indexing or the 3D content retrieval procedure, to compare body or 3D geometries is the presence of a 3D-Repräsenation of the 3D objects in the form of a boundary representation model (B-REP) a constructive solid geometry (CSG) or triangular look or networked representations of surfaces such as STL model. Pictures, scans, or 2D do not work for this procedure only once. You should only convict them in a 3D-Repräsentation.

These first two object forms are produced mainly in industrial practice by CAD systems. This is done through the geometry engine CAD software, the core of geometry or even modeling core of CAD software. Widespread geometry cores are E.g. the ACIS kernel from the firm spatial or SIEMENS PARASOLID-kernel. On these systems, there are a number of other systems, which are used in some very specific. That special programs be used in tool and mold making, medical technology, electrical engineering. Ultimately, these systems also generate only 3D-Repräsentationen of the corresponding geometric objects. About well-known interface formats such as STEP, ACIS, JT, IGS, then, these systems can exchange model data.

The commercially available 3D CAD systems including CATIA, solid works, Creo, inventor, Siemens NX, solid edge, etc. create their models on the basis of the above-mentioned two modeling kernels.

For use in practice, the shape indexing should be methods for geometric similarity search able so easily to recognize this object forms and process. These 3D objects are to extract then relevant characteristics that allow a geometric comparison for the evaluation and assessment of the similarity of the objects.

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