The radius of the outer circle is defined by the total number of pixels in the map. If the polar diagram does not reach the outer circle, no data (NULL) pixels were found in the map.
The vector in the diagram points into the prevalent direction of the angles, its length is defined by the power of this direction.
As a side effect, the quality of the angle map can be derived from the diagram. Strong spikes may indicate an over-representation of the related angle(s) which happens in particular if integer maps are used.
Polar diagram of aspect map
Last changed: $Date: 2006/02/20 17:46:42 $