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Please bear with me here - I'm pretty new to GIS, and I'm having a lot of confusion about all the different terms I've seen thrown around.

Here's my problem: I have a large dataset of point features, all within a arbitrary geographical area (in this case, the greater San Francisco Bay Area). The point features have no other information besides lat/long.

What I want to do is display them in such a way that I can easily see concentrations. I think what I'm looking for is called a heatmap, although I've also seen things like "kernel density", "point density" and other terms.

The base of my map is several layers I got from a large dataset. That means that I don't really have a polygon layer that is just the area I'm looking at - the main layer is a polygon feature class of counties in the Western United States. I could extract just the counties I'm interested in if that would make this process easier.

I'm looking for something like the images in dkwiens' post in this thread.

What do I need to do? The simpler the explanation, the better - I've spent quite a while on Google looking for this, and while I've found a lot of stuff that seems like it's what I want to do, I haven't been able to translate it to my problem.

Edit: I should mention that I think the closest I've gotten is with the point density tool. I set the "input point features" to the layer containing my points, the "Population" field to NONE (the other options are X and Y), and a cell size of 50. I've tried several values of Radius, both in map units and in cell units (whatever that means!). After running the tool, I get a layer that looks like the attached screenshot. But nothing actually shows up on the map. Here's the screenshot: http://i41.tinypic.com/35n7itu.jpg

Edit2: I noticed that when I look at the generated "File GeoDatabase Raster Dataset" in ArcCatalog, the preview tab has nothing in it - just a blank white screen. Not sure if it's supposed to be like that or not.

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Is this the tool you are looking to use, resources.arcgis.com/en/help/main/10.1/index.html#//…? –  artwork21 Apr 28 '13 at 16:30
    
Maybe? I'm not sure if that's the right tool. I've tried it, and I get a similar result as the screenshot of the result of the point density tool - it creates a new layer, but nothing shows on the map. –  Isaac Dontje Lindell Apr 28 '13 at 16:38
    
Try creating a population/count field and put a value of 1 for each feature, then run the tool. –  artwork21 Apr 28 '13 at 16:39
    
Same result - a new layer but nothing added to the map. Based on my reading of the docs, a population field should not be necessary anyway. If the Population option is set to None, it will just count each point once (which is what I want). –  Isaac Dontje Lindell Apr 28 '13 at 16:50
    
Check that your point data should be defined in a projected coordinate system and not a geographic one. –  artwork21 Apr 28 '13 at 17:14
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1 Answer 1

up vote 1 down vote accepted

To summarize my comments above:

When running a spatial analysis tool on geographic lng/lat tabular data follow these steps:

  1. Make sure your data frame is set to GCS WGS 1984
  2. Create your x/y event layer
  3. Export your event layer out to a new layer (to data frame spatial reference)
  4. Re-project your layer to a PCS using the Project tool
  5. Run your spatial analysis tool (e.g. Kernal Density)
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Again, thanks so much! I've definitely got a ways to go in the GIS world. –  Isaac Dontje Lindell Apr 28 '13 at 17:50
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