1

I am trying to visualize a set of pois on a map with the qgis heatmap plugin.

It works great with a big radius but the layer is invisible for a small one (around 100 meters). I really need a small radius as I want to be able too zoom and see local results.

How can I do?

2

Try increasing the resolution of your output grid. In the advanced section there's settings for rows and columns - try bumping these right up. This will lower the size of each pixel in the grid and should allow you to see the heatmap with a small radius.

  • It doesn't work. With too small values nothing appears and with too big values my laptop computes forever and the file gets too big (hundred of gb). Is it some faster alternatives to generate heatmaps? – Frederic Le Feurmou Oct 31 '14 at 14:19
  • Can you share some more details? The projection and layer extent would be helpful. – ndawson Oct 31 '14 at 19:25
  • I compute all the bars (5804) in france from OSM data. The selected CRS is WGS 84, the authority id is EPSG:4326 and my SRID 900913. I tried with radius between 500m and 1km. – Frederic Le Feurmou Oct 31 '14 at 20:19
  • How many rows/columns does that say it will output (at 100m)? I suspect its simply too large an area to generate a heatmap at this fine a resolution. You may need to split your area up into segments and do each individually... – ndawson Nov 1 '14 at 21:37

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