I have a point map of trees along with their size (diameter) as an attribute and I want to create a raster that with the output of a neighborhood analysis
Basically for every point in a raster of specified resolution, I'd like to make the following calculation
For every tree within radius r, sum up for all trees.
(tree size)^2 / (distance from center)^2
Note that this is getting the quotient for each tree individually, then summing the up and assigning the middle pixel that value.
I can't picture this working with with the raster calculator or focal analysis tools, so I think I'd have to program something, but I'm not very experienced using Python.
I am using ArcGIS 10. And have tried various ways of looking at both Focal Statistics and Point Statistics. The problem with both of these is that they summarize on a single attribute. That is, I can get point densities for a given area, or I can sum up tree sizes for a given area... Dividing those two layers dones't quite give me what I need.
If I were to do this by hand, I would repeat these steps in a grid every 5 meters
- Identify all trees within radius
- Get size of each tree
- Divide each tree by the distance^2 from the center
- Add up the quotients for all trees within radius
- Assign that sum to a raster pixel at the point center
I've been able to do this analysis in R using a loop that goes through each point, but I'm not familiar with Python, so I hoped I could do this out of the box