Is it possible to get the radius' density kernel of the heatmap in meters rather than in pixels? http://suite.opengeo.org/opengeo-docs/cartography/rt/heatmap.html
If not, is there other alternatives to draw heatmaps efficiently from my postgresql db and send it to leaflet? (I tried heatmap.js but it is quite slow)
Because you are using a raster tool, the radius of your filter has to be expressed in pixels. If you need a more precise solution, you must use a smaller pixel size. This is a constraint from the method and not from the software.
If you need to start with an input value in meters, you can convert your "meters" in "number of pixels" in a previous step. This is quite straightforward if you are using a projected coordinate system (round(radius_in_meter/pixel_size)). If you are in lat/long, it is not recommended to use this kind of conversion.
