[gdal-dev] About gdal RasterizeLayer

Frank Warmerdam warmerdam at pobox.com
Tue May 4 11:07:16 PDT 2021


I can't seem to find this in the docs, but I think what you want is
"MERGE_ALG" set to ADD instead of the default REPLACE.


This doesn't address the buffering (I guess you might still want to buffer
the whole set), but it should take care of the additive step.

I actually implemented this as part of a programming test for my current
job - to build heatmaps of satellite coverage.

Best regards,

On Tue, May 4, 2021 at 1:30 PM Miguel A. Manso <m.manso at upm.es> wrote:

> Dear all
> I have a multiline layer type (tracking) and I want to make a heat map
> (densities) on a buffer of them, so that in those places where several
> buffers overlap the density is added as many times as lines overlap.
> Now I'm doing it with a python script that reads from a shp the lines,
> generates a buffer and rasterize the polygon filling it with a given
> value with gda.RasterizeLayer(). I read the image as an array and with
> numpy I add it to another array (accumulating). When I finish I convert
> it to an image and save it in a geotiff.
> This procedure is relatively slow. Especially if you have to do it for
> many lines.
> My question is along the lines of whether the RasterizeLayer function
> itself could do this process in a more efficient way, making the burning
> of the objects not an OR operation but an arithmetic sum...
> Any suggestions would be welcome.
> Regards
> Miguel A. Manso
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