Please could someone give me some advice on creating heatmaps in QGIS? I have tried to create these through both QGIS and GRASS, and fail miserably each time. In QGIS, I either receive an error that not all the fields have been filled in, which I most certainly have done, or it fails to render anything remotely resembling a heatmap. In GRASS, it takes hours to render and the final result is just a bunch of colourful, concentric circles. What am I doing wrong?
- I'm using QGIS 1.8.0-Lisboa, using the heatmap plugin via Raster ---> Heatmap ---> Heatmap
The data I am using is fire point data from NASA's Aqua and Terra satellites. As far as workflow is concerned, I've tried the 3 methods shown in the tutorial:
a) Open vector point shapefile, then select 'Heatmap' as per above, provide an output raster name, set the radius as 100000 (100km), decay ratio as 0, click on advanced, x=100, y=100. This usually produces a blank or a grey rectangle (with a lot of holes in it).
b) Using the GRASS v.kernel module: Open the mapset (created previously). Go to GRASS Tools and select v.kernel, then select the input vector and enter 1000 as the Standard deviation, but when I run it, an error appears which says the input vector and standard deviation have not been entered.
c) From GRASS tools, I select GRASS shell, then enter v.kernel in the commandline interface. This takes hours and is what delivered the concentric circles. Not sure how to share the data? Still new on the forum and wasn’t allowed to include a screenshot.
