I have a polygon data set of corn yield collected by a combine. However, as the combine drove through the field, there was slight overlap between passes, leading to overlapping polygons within the same shapefile. I also have a point dataset of sampling sites within the field. Occasionally, these points fall on locations where two polygons are overlapping. At each point, I would like to extract the value from whichever polygon has the higher yield.
I've thought of two ways to do this:
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If I can extract the values from both polygons to the attribute table, I can process the data in Matlab to get the maximum. However, most of the points are entirely contained within one polygon. I've tried doing a 'Join by spatial location' but because the polygons are in the same layer, it will only join one of the two records.
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Create new polygons for all the overlapping areas and then use join to extract the data.This example from Grass seems to do what I want, but I don't know how to do the behind-the-scenes programming. Is there a built-in function of Arc that can do the same thing?
I am using ArcMap 10 with spatial analyst. There are hundreds of polygons overlapping, so I'd like to use some sort of automated extraction.
Best Answer
And another way:
Do a spatial join of the polygon data to the points and set the field mapping merge rules to 'Max'.