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Raster Geoprocessing

Question asked by greenlincoln on Nov 25, 2013
Hi. I am trying to use arcmap and the geoprocessing tools to calculate the directly connected impervious area, pervious area, and not directly connected impervious areas for a single drainage inlet location. I have two sets of raster data that I am trying to use to accomplish this goal and I'm hoping to get an output of a single raster with three ObjectIDs (one for each of the area types). An image of my initial data sets has been attached.

I have one raster that is composed to two ObjectIDs, impervious area and pervious area. I have another raster that is of the bulidings within the catchment. I was able to obtain the result i was looking for using the Region Group tool and the Raster Calculator. I used the region group tool to find the directly connected area to the inlet location by excluding the value of the pervious area (2). The only problem was, I had to use the reclassify tool on the output from the Region Group tool because it resulted in an object for each seperate impervious area (I only want it split into the three area types), and there was no way to know which output ID would be the one that is actually attached to the inlet location. After i reclassified the region group output, I used the raster calculator to combine the two raster data sets into one with the three ObjectIDs. I have attached an image of my results.

The problem with this method is that it is labor intensive and it would not be a good method if I was trying to perform these calculations for multiple catchments.

So, my question is if anyone can help me find of a more efficient way to perform these calculations? Thanks in advance for any help.