I'd really like to repeat the functionality of the ArcGIS Kernel Density tool - how could I do that?
I would like to limit answers to easy-to-install free-and-open-source software – i.e. QGIS installs easily with GRASS on all platforms so QGIS+GRASS would be fine, but SAGA does not (unfortunately, since it has what may be the ideal tool).
I am trying to produce density maps of wildlife across protected areas in QGIS. The density map in the following example was produced in ArcGIS from point observations of wildlife, with raw counts of group size (a field in the vector file) used to weight the density of each grid cell in the Kernel Density (SpatialAnalyst) tool, with a chosen search radius and grid cell size:
In a previous question on density, it was suggested to use the GRASS v.kernel tool to mimic the ArcGIS Kernel Density tool, but v.kernel doesn't do the same job. After looking at the manual and (successfully) producing a density map, it seems that the v.kernel function only works with point density, and there is no opportunity to give a variable for each point (such as raw counts) to weight each point.
There seem to be various
*.surf.* tools in GRASS that may help create a density surface - and these do accept a weighting column or z-value, or are performed on rasters. @underdark suggested v.surf.rst - and the 'zcolumn' would be my weighting (count) variable - but I cannot figure out how to ask the tool to create a certain grid size or use a certain radius.
Suggestions on how to use v.surf.rst or any other method?
x,y,count 431250,8707500,0 418750,8707500,5 413750,8707500,3 411250,8707500,1 408750,8685000,0 411250,8685000,0 416250,8685000,0 416250,8682500,6 411250,8682500,3 418750,8680000,0 433750,8677500,3 421250,8677500,0 423750,8675000,1 431250,8672500,0 428750,8672500,2 426250,8672500,2 423750,8670000,0