TRANSLATION-, ROTATION- AND SCALE- INVARIANT RECOGNITION OF HAND-DRAWN SYMBOLS IN SCHEMATIC DIAGRAMS
- 1 March 1990
- journal article
- Published by World Scientific Pub Co Pte Ltd in International Journal of Pattern Recognition and Artificial Intelligence
- Vol. 4 (1) , 1-25
- https://doi.org/10.1142/s0218001490000022
Abstract
In this paper, a model-based scheme for recognizing hand-drawn symbols in schematic diagrams using attributed graph (AG) matching in the absence of any information concerning their pose (translation, rotation and scale) is described. The process of AG matching proceeds as follows. First, an observed AG (AGO) is constructed from single-pixel-width line-representation of an observed symbol. Second, the pose of the AGO is estimated in terms of translation, rotation and scale with respect to the model AGs (AGM s ). The search space is effectively pruned by introducing the concept of control vertex and applying geometrical constraints in an early stage. In this step, a small number of candidate AGM s are selected. Third, correspondences between components of the observed AG after normalization (AGON) and those of the AGMs are found for the given poses. Fourth, distance measures between the AGON and the AGM s are calculated, based upon the correspondences. Finally, the AGON is classified as the AGM with the minimum distance. Experimental results for hand-drawn symbols with and without templates show that using AG matching is very efficient and successful for translation-, rotation- and scale-invariant recognition of hand-drawn symbols in schematic diagrams.Keywords
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