An interactive tool for calculation of the area of an irregular polygon defined by boundary coordinates.
Notes on Spatial Analysis - Area of an Irregular Polygon
- Coordinate entries must be consecutive ... an X=Y=0 entry is taken as undefined and determines the end of the entry sequence for less than 10 points.
- Points should be entered in clockwise sequence ... an anti-clockwise sequence results in a negative (otherwise correct) area.
- The polygon boundary should not cross itself once all points are defined ... a crossed boundary results in an invalid area calculation.
- -1 000 000 < X < 1 000 000 ... increasing to the right
- -1 000 000 < Y < 1 000 000 ... increasing upwards
Values displayed with a may be changed ... click on a value to display an entry form ... or use the arrows right of a value to select from a list.
This tool exhibits spreadsheet-like behaviour ... change a value and related values are re-calculated automatically.