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I have a point dataset generated from getting the centroid points from a fishnet/polygon grid. I combined these points using a spatial join to give them an attribute of 'pressure' which is an integer value.

In either qgis, postgis or cartodb (i.e. using CSS styling options) is there any way to display these data as a heatmap with the heat generated by the pressure value rather than the point density?

I've already made a map with graduated symbols based on the pressure but i'd like a more traditional heatmap view.

A workaround I had been thinking about was to put a proportional number of points in each polygon in the grid and generating a standard heatmap of point density but this doesn't seem like a very efficient method so I want to rule out other options first.

Another thought I had was to try and draw best fit contour lines and styling them appropriately but I wasn't sure if I could use a point vector input to create contour lines like this.

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    The Heatmap layer style in QGIS has an option to use a field as the value driving the heatmap... – DPSSpatial May 3 '16 at 16:47
  • This works really well thanks, is there anyway so that only the areas with >0 have the heatmap applied, rather than a uniform color? – hselbie May 3 '16 at 17:13
  • i.e. currently the heatmap has the hot areas correctly styled and then a uniform tope color over the rest of the map. I can adjust the transparency but I'd prefer to just have the heatmap apply over where the data is. – hselbie May 3 '16 at 17:19
  • post a screen capture in your answer below... can't figure out what you mean... – DPSSpatial May 3 '16 at 18:06
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Thanks to the comment above from DPSSpatial, I have found that the heatmap style in QGIS 2.14 style properties works great for this purpose. I can edit the color ramp so that it is transparent on one end and weight the heatmap based on the pressure value to create the heatmap I'm looking for.

Many thanks all.

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