Area - ObjectVision/GeoDMS GitHub Wiki
Geometric functions area
syntax
- area(polygon_data_item, valuesunit)
definition
area(polygon_data_item, valuesunit) calculates the surface of the polygon_data_item argument, in the image the green hatched area.
The resulting values unit is configured as second argument.
description
The resulting area values need to be positive; if the values are negative it means the order of points in the polygon geometry is not according to the following rules:
The order of points in a sequence needs to be clockwise for exterior bounds and counter clockwise for holes in polygons (right-hand-rule)
applies to
- [data item]] polygon_data_item with fpoint or dpoint [[value type]] and [composition type polygon.
conditions
The metric of the values unit argument must match with the square of the metric of the coordinates in the coordinate system.
example
attribute<m2> surface (district) := area(district/geometry, m2);
| district/geometry | surface |
|---|---|
| {21 {403025, 113810}{4 | 1003100 |
| {17 {400990, 113269}{4 | 474460 |
| {19 {401238, 115099}{4} | 1246460 |
domain district, nr of rows = 3