Table 1 Regions and corresponding rules for discarding interior points
From: CudaChain: an alternative algorithm for finding 2D convex hulls on the GPU
Region | First point | Last point | Order of x coordinates | Order of y coordinates | Rule for discarding |
|---|---|---|---|---|---|
Lower left (\(\hbox {R}_{1}\)) | \(P_{minx}\) | \(P_{miny}\) | Ascending | Descending | Sort x in ascending order first; Discard point P according to the rule listed in Fig. 2a |
Lower right (\(\hbox {R}_{2}\)) | \(P_{miny}\) | \(P_{maxx}\) | Ascending | Ascending | Sort y in ascending order first; Discard point P according to the rule listed in Fig. 2b |
Upper right (\(\hbox {R}_{3}\)) | \(P_{maxx}\) | \(P_{maxy}\) | Descending | Ascending | Sort x in descending order; Discard point P according to the rule listed in Fig. 2c |
Upper left (\(\hbox {R}_{4}\)) | \(P_{maxy}\) | \(P_{minx}\) | Descending | Descending | Sort y in descending order; Discard point P according to the rule listed in Fig. 2d |