Ask A Cartographer

Point Location Error and Raster Extractions

February 16 2010 | 0 comments
Categories: Map Data

When extracting raster layers of a given resolution to point locations, how much smaller should the coordinate error of the points be than the resolution of the raster layers? For instance, if the raster resolution is 1km, should the coordinate error of points be <= 1km, or is there a more conservative rule of thumb?

### Mapping Center Answer:

When you convert a raster to points, the point location will be assigned to the centroid of the cell.  If your cells are 1 kilometer square, then the point location could be up to .706 kilometers off (the distance from the centroid of the cell to one of the four corners of the cell. If this is not an acceptable amount of error, then you should use a more precise raster with finer resolution, but be aware that simply resampling the raster to a finer resolution does not increase the inherent precision of the raster.

If you would like to post a comment, please login.