The plugin uses island similarity detection in the following situations:
- Select Similar operator - selects all islands which have similar shape to islands which are already selected.
- Align Similar operator - aligns selected islands, so islands which are similar are placed on top of each other
- grouping islands by similarity.
Accuracy of similarity detection depends on three factors:
Similarity Threshold parameter: a greater value of this parameter means islands will be more likely recognized as a similar in shape. 0.5 is a good threshold value to start with
Precision paramter: more precision means better accuracy in looking for similar islands. Precision set to 200 should be sufficient in most cases. This value should be increased in the first place if the similarity detection returns incorrect results (especially when dealing with really small islands)
Rotation Step paramter: the lower rotation step value the better accuracy of the operation. Rotation step set to 90 should be sufficient in most cases though