I'm pretty new to GIS.
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.
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:
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.
Best Answer
To summarize my comments above:
When running a spatial analysis tool on geographic lng/lat tabular data follow these steps: