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I'm using .shp files built from .csv files and having quirky results. Perhaps there is a better way to begin.

The heat map appears to be accurately describing the data but calculates a huge area in relation to the data and so the cell size is way too large for smooth detailed map.

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Why would this have anything to do with the input file type? The raster cell size is something you configure when rasterizing or in the plugin if it takes care of that for you. –  lynxlynxlynx Feb 22 '13 at 23:53
    
Check the extent of your input point layer - there may be errant points that lie far away from your target area. –  Simbamangu Feb 23 '13 at 7:48
    
When I hit zoom extents with just the point layer visible, I get a nice tight set of points (all that I expect to be there) that fill the sreen. When I do the same with also the heat map visible, I get the heat map layer and a tiny cluster of totally indistinguishable points in the center. –  Fred Feb 23 '13 at 11:44
    
I can work the color map; when it sets itself up I get an equal value spread of 0 -...- 184 and I get a totally mono-chrome field. If I tweak the color map all the way up to something like, 183.8 -...-184.8 then I get what looks like an accurate calculation but only of an area of about 4 X 4 cells over my data. –  Fred Feb 23 '13 at 11:51
    
And yes, lynxlynxlynx, the plugin takes care of it and I think that's my problem. Simbamangu's explanation makes perfect sense if the zoom extents was catching the errant data. Is there any possibility that zoom extents doesn't see something that the heat map plugin does? Is there perhaps something else in the cvs file that might snag the plugin? –  Fred Feb 23 '13 at 11:55
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