2.6.2. Building a model for each sh

2.6.2. Building a model for each shape category
Fifty representative oyster images for each shape category are selected and their turn angle functions are calculated. As shown in Fig. 6, every one of these 50 turn angle functions is ‘‘aligned” with the turn angle function of a selected reference oyster using the proposed TAC similarity measure (the cross-correlation value is minimum when they are aligned). Because of slight variation in oyster shape and minor segmentation error, the resulting aligned 50 turn angle functions belonging to the same shape category will not be identical (TAC similarity measure is not 0). The average (after eliminating outliers) of these 50 aligned turn angle functions is used as a model (called type model) for each shape category. Fig. 7 shows a type model generated for good shape quality.