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I have downloaded a very handy raster dataset generated by the Nature Conservancy for identifying terrestrial habitat cover types in the north east. Link to the project info and a link containing a download of the raster dataset (right hand side of page) is here:

https://www.conservationgateway.org/ConservationByGeography/NorthAmerica/UnitedStates/edc/reportsdata/terrestrial/habitatmap/Pages/default.aspx

I'm not terribly experienced when it comes to working with raster files. All I intended to do with this data was query which habitat types occur within a quarter mile of a series of reservoirs in New York. However, select by location is not an option with rasters. I've tried converting the raster to polygon but not only are the polygon boundaries slightly off, there is no information retained in the resulting attribute table that would let me join the original dataset info to the resulting shapefile. Does anybody know how I can go about inventorying the habitats in my study area?

I have attempted to research a solution however I've come up short. I have access to Spatial Analyst and an Advanced license.

  • When you vectorize a raster there can be some shifts depending on resolution and smoothing. Raster to Polygon either takes the field you specify and as the attribute of the polygons, or if you don't specify it uses cell value in an attribute called gridcode. Your raster likely has coded int values (2=forest, 3=meadow, etc.), so resulting polygons should have an attribute with that code. You'd need to make a new attribute with that text key or if you have a raster attribute table join to that based on code field. – Chris W Apr 16 '15 at 1:13
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Are the reservoir data you have vector data (points or polygons)? If so, your best bet is to make a quarter-mile buffer around the reservoir using the Buffer tool. Then, use Zonal Statistics in the Spatial Analyst extension to extract the raster values. I'm not sure what values are associated with your raster layers, but you may have to investigate using the Reclass tool to assign each habitat type a certain numerical code.

Hope that gets you started in the right direction.

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  • Actually, given the target is a list of class values within an area, the Zonal Histogram tool might be a better fit than zonal stats. – Chris W Apr 15 '15 at 20:02
  • Thank you both, I will try both of those options. I was also able to use the Clip function to make a smaller, much more manageable raster which filtered the data in the way I needed. – Ross Apr 15 '15 at 21:36

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