I am super new to QGIS so I may be doing something really dumb, but it doesn't seem to work to create a heatmap in QGIS Desktop 2.8.2 (just downloaded this yesterday so I think it is the most current stable release). I load my points in from a SQL server geometry column, then click Raster > Heatmap > Heatmap. Then I change none of the defaults on the "Heatmap Plugin" dialog except where to save the raster and hit "OK". The resulting raster looks like it uses very few of the points in the "Input point layer". Is there any way to get this to use all the point when constructing the heatmap?
Here are some pictures showing this process:
After loading all my points:
Heatmap Dialog Box:
After hitting OK on the Heatmap dialog box above and it renders (a progress bar dialog that isn't in the picture pops up for a minute after hitting "OK"):
This is what the rendered tiff looks like when I open it in Photoshop: