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Introduction

The MatcherTool provides 3D model creation and matching facilities. The model matcher also computes the transformation which takes the model into the scene. The model matcher bases its initial matching hypotheses upon partial congruencies identified between scene descriptions and subsets of features chosen from the model. Each such subset (or "group") of model features provides a matching context/cliche. This embodies certain viewpoint dependencies and allows the computational expense of exhaustive search to be avoided. Furthermore, in order to reduce complexity yet further, a single feature in the group, the focus feature, is required to have a good match at all times (Tina memo 2003-006).

Models and their matching contexts (focus features and associated groups) can either be read from files (see Appendix for a definition of the format of these files), generated at run time, or a combination of both (the model read from disc and the allowable matching contexts determined at run time). Once the model has been obtained the process of matching it against a current scene description (assuming it has already been obtained in the usual way using the Edge tool) has 2 stages. The first is to build a pairwise relations table for the model and scene; this contains information about the invariant relationships between pairs of features. The second is to perform a constrained search over the tables of the model and scene to identify cliques of above threshold cardinality between matching features. These are used to compute potential transforms and recruit further matches. The model matcher has specialised File/View facilities for reading/writing, and display/manipulation of scene and model data. Using the view facility and associated Tv devices (model andscene) the matched model can be displayed in the transformed position over the scene description. The matcher has 2 parameter cycles and toggle selectors for adjusting various pair wise relationships table and matching algorithm parameters.


next up previous contents
Next: Standard Usage Up: Matching Tool Previous: Matching Tool   Contents
root 2017-11-17