On 12/5/2011 6:45 PM, Puneet Kishor wrote:
I am looking to create some heatmap-ish or DEM-ish spatial
distribution visualizations. Any suggestions on how to go about doing
so given a lon-lat containing geom column in PostGIS?
Puneet,
Here is the logic I would use, but I have not played with the raster
code at all so I'm not sure how to put this into SQL terms for you.
The idea is to have a sample dot like a sphere bright in the center and
decreasing intensity as you move outwards, play with the radius for best
results. maybe start with 9, 15, or 19 to start with.
Create an empty raster. Then select your points and for each points and
for each one "add" the sample dot centered on your location to to the
raster. By "add", I mean you need to add the value of the pixels in the
dot to the pixels in the raster. So raster=1 + dot=3 => raster=4 and
limit it at maximum saturation. This should work for multiple channels
also. This should give you a heat map.
-Steve
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