I'm using the v.kernel function in GRASS to create heat maps. I am able to generate an acceptable heat map using a std deviation of .2 and a several thousand rows and columns. After the map is generated, I look at it in QGIS.
v.kernel input=data output=heatmap stddeviation=.2
However, if I go to a std deviation below .2, all I get is a black rectangle. A std dev of .19 or .1 or .01 results in no variation being shown on the heat map, just all black. Does anyone know why this might be? I want to be able to increase the granularity and precision of the maps I'm creating, and lowering the stddeviation would seem to be the solution.