Building density maps with large geocoded datasets?

Question

I have a data set with over 50,000 geocoded points (lat-long). Each point has a set of data associated with it -- things like quality, status, etc.

I'd like to make a set of density maps showing the distribution of data by those metrics. For example, one map would show the density of all items with a quality of "good".

With a smaller set of points, I'd use Google Maps and custom markers. Here, however, different segments have tens of thousands of points

Are there any APIs or libraries that could help me do this?

---

The solution I will be going with:

1. Break the area to be mapped into a grid.
2. Count the number of entries falling inside each square.
3. For each square, generate a PNG with transparency relative to the number of entries.
4. Populate a Google Map with this set of PNGs as markers.

Answer 1

One solution could be to create bitmaps with your density maps and add them (only one at the same time) as overlay on your google map (with GGroundOverlay)

You may have a look at this post that gives an example of density map with google map. It uses the HeatMapAPI. Unfortunately, this API is not free if you use it with a large number of points...

Put build your own density bitmap may be not so complicated...

One other solution is to reduce the number of markers you can use. It could be done with the MarkerClustered library. It is not exactly a density map, but... can maybe be useful.

Answer 2

http://heatmap.codeplex.com/