Arc2segm - ObjectVision/GeoDMS GitHub Wiki
Geometric functions arc2segm(ent)
- arc2segm(arc_polygon_dataitem)
arc2segm(arc_polygon_dataitem) divides an arc or polygon data item arc_polygon_dataitem into segments.
The function results in a new domain unit with three subitems:
- point: a point data item with the first point of each segment;
- nextpoint: a point data item with the last point of each segment.
- sequence_rel: relation to the arc_polygon_dataitem
The arc2segm function is used to split an arc geometry into intermediates that become nodes in a network. This operator can also be applied to polygons; however, when the set includes lakes, it generates "lines" for the connecting lines.
data item arc_polygon_dataitem with fpoint or dpoint value type and composition type arc or polygon.
O(n) where n = total number of points across all arcs/polygons. Single pass creating one segment for each pair of consecutive points.
unit<uint32> segments := arc2segm(road/geometry);
| road/geometry |
|---|
| {2: xy(112631; 399246) xy(111866; 398599)} |
| {3: xy(111866; 398599) xy(111924; 399495) xy(111524; 401801)} |
| {2: xy(114921; 401529) xy(114823; 398584)} |
domain Road, nr of rows = 3
| point | nextpoint | sequence_rel |
|---|---|---|
| xy(112631; 399246) | xy(111866; 398599) | 0 |
| xy(111866; 398599) | xy(111924; 399495) | 1 |
| xy(111924; 399495) | xy(111524; 401801) | 1 |
| xy(114921; 401529) | xy(114823; 398584) | 2 |
domain segments, nr of rows = 4