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I have a USDA Statsgo soil polygon featureclass stored in a file geodatabase along with an attribute table; I have a one-to-one relationship class defined based on the soil type field. When I bring the featureclass into ArcMap I can view the attributes in the related table when I use the identity tool.

What I would like to do is create a raster from this featureclass using values from the related table. This seems simple enough, but when I used the Polygon to Raster conversion tool the only fields available to use are those which are stored in the featureclass itself. If I define a join on the same featureclass and table I can then select the appropriate field in the joined table, which makes me wonder why I bothered creating the relationship class in the first place (resulting raster values are numeric - I lose my classification codes of A through D).

Can anyone explain 1) why I can't use the relationship class to access fields in the related table, and 2) how to keep the alphabetic soil classification codes?

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  • This says "any field of the input feature dataset's attribute table". May be another finicky aspect of ArcMap. Have you considered using join field?. This appends a new field, without relying on relationships. Also, says "If the input field contains string values, the output raster will contain an integer value field and a string field." – Barbarossa Feb 20 '14 at 18:12
  • Despite the fact that it says it will create an integer and string field if the input field is a string, the only output I get is an integer along with a count of how many cells have that value. – Jason Feb 20 '14 at 18:33
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I've found the solution to the second part of my question on how to keep the alphabetic soil classification codes. I discovered that the Polygon to Raster tool finished, but with a warning. Apparently it doesn't like the name of the joined field, "muaggatt.hydrgrpdcd". When I create a new field in the featureclass called "hydrgrpdcd" and then populate it with the values from the joined table the tool runs as expected and I get string output along with the integer. I still don't know why I can't use the relationship class I defined between the featureclass and the attribute table, but at this point I have a work around and that will suffice.

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It is possible to use a joint field for the conversion from vector to raster. However, you need to know that the join is stored on the raster layer, not in the raster data. Therefore, when you want to use a tool with a joint table, you must select it using the drop down list and not the folder.

Concerning the data type, the data will always be stored in a numeric type, but if you have a small integer type you can build a raster attribute table, and you can join your descriptions to the attribute table.

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  • I'm not sure I follow you there. The only join I have is the one between my featureclass and the attribute table. – Jason Feb 20 '14 at 20:45

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