Re: [gdal-dev] About gdal RasterizeLayer
Hi, I tried if someone who don't know Python could do about the same with gdal_rasterize https://gdal.org/programs/gdal_rasterize.html and I had some success. gdal_rasterize -dialect sqlite -sql "select st_buffer(geometry,0.01) from states" -burn 100 -of GTIFF -ot byte -tr 0.1 0.1 -add states.shp testburn.tif I used byte type and burn value 100 for making quick visible result. The default type is Float64 and it has room for much more overlapping geometries than two. -Jukka Rahkonen- Frank Warmerdam wrote > Miguel, > > 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. > > https://github.com/OSGeo/gdal/blob/master/gdal/alg/gdalrasterize.cpp#L1165 > > 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, > Frank > > > On Tue, May 4, 2021 at 1:30 PM Miguel A. Manso > m.manso@ > 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 >> >> >> ___ >> gdal-dev mailing list >> > gdal-dev@.osgeo >> https://lists.osgeo.org/mailman/listinfo/gdal-dev >> > > > -- > ---+-- > I set the clouds in motion - turn up | Frank Warmerdam, > warmerdam@ > light and sound - activate the windows | +1 650-701-7823 > and watch the world go round - Rush| Geospatial Software Developer > > ___ > gdal-dev mailing list > gdal-dev@.osgeo > https://lists.osgeo.org/mailman/listinfo/gdal-dev -- Sent from: http://osgeo-org.1560.x6.nabble.com/GDAL-Dev-f3742093.html ___ gdal-dev mailing list gdal-dev@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/gdal-dev
Re: [gdal-dev] About gdal RasterizeLayer
Miguel, 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. https://github.com/OSGeo/gdal/blob/master/gdal/alg/gdalrasterize.cpp#L1165 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, Frank On Tue, May 4, 2021 at 1:30 PM Miguel A. Manso 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 > > > ___ > gdal-dev mailing list > gdal-dev@lists.osgeo.org > https://lists.osgeo.org/mailman/listinfo/gdal-dev > -- ---+-- I set the clouds in motion - turn up | Frank Warmerdam, warmer...@pobox.com light and sound - activate the windows | +1 650-701-7823 and watch the world go round - Rush| Geospatial Software Developer ___ gdal-dev mailing list gdal-dev@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/gdal-dev
[gdal-dev] About gdal RasterizeLayer
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 ___ gdal-dev mailing list gdal-dev@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/gdal-dev
