Points to raster
Algorithm
The Points to raster operation rasterizes a point map. The output raster map always uses the same domain as the input point map. The user has to specify the georeference for the output raster map.
Process:
If the chosen point size is 1, then for each point, the corresponding pixel in the raster map is found; this pixel is assigned the class name, ID or value of the point. Other pixels obtain the undefined value.
If the chosen point size is larger than 1, then a square is drawn around each point with the specified size in pixels. All pixels inside this box are assigned the class name, ID or value of the point. Other pixels obtain the undefined value.
- The pixel size indicated in the georeference for the output map, has a large influence on the size (in bytes) of the output raster map. Mind that rasterizing on a pixel size of 10 m instead of 50 m increases the size of the raster map by a factor 25.
- If you want to rasterize only a portion of your point map, you can either select or create a georeference that does not cover the total area of your point map during rasterization, or you can first create a SubMap of the point map and then rasterize this submap.
For ILWIS 1.4 users:
- During rasterization, an .INF table is not produced anymore. To know the area of polygons, length of segments, nr. of points etc., you can calculate the histogram of a polygon, segment or point map with the Histogram operation.
- To rasterize attribute values of a point map, first create an attribute map of the point map with the Attribute map of point map operation, then rasterize this attribute point map.
- When rasterizing a value point map, it is not yet possible to sum the values of points that would fall in one pixel.
See also:
Points to raster : functionality