Grouping of Isolated Non-directional Cues with Straight Offset Polygons

When the boundary of a familiar object is shown by a series of isolated dots, humans can often recognize the object with ease. This ability can be sustained with addition of distracting dots around the object. However, such capability has not been reproduced algorithmically on computers. In this paper, we will introduce a new algorithm that groups a set of dots into multiple overlapping subsets. It first connects the dots into a spanning tree using the proximity cue. It then applies the straight polygon transformation to an initial polygon derived from the spanning tree. The straight polygon divides the space into polygons recursively and each polygon can be viewed as grouping of a subset of the dots. The number of polygons generated is O(n). We used both natural and synthetic images to test the performance of the algorithm. The results are encouraging.