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I am working on a distance model that creates distance rings around a given point and assigns those rings a probability. The point is in the center of a 25 x 25 km area, and the model fails to assign a probability to the area that is outside of the rings but inside the 25 x 25 km area. How can I build a simple model in model-builder where I can merge the two layers together and assign probability to the area that is not included in the model? The probability that I want to assign to the outside area is 5%.

Thank you

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Probably should have asked before answering - are you using raster or vector data? – om_henners Aug 8 '12 at 13:32
It is a vector data that I will later convert into a raster – user8759 Aug 8 '12 at 13:37

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Use the Feature Evelope to Polygon tool to create the 25km square. Calculate the probabilities for the rings as previously (I assume with Multiple Ring Buffer) and then Union them with the 25km square - this will leave null values for the regions of the square outside the rings. Then simply calculate a new probability over the nulls using Calculate Field.

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How can I calculate the field value of only one polygon using the calculate field? I don't want it to change the field values for my other rings... – user8759 Aug 8 '12 at 13:51
Either make a selection using Make Feature Layer and then calculate the field, or use an expression in Calculate Field so it ignores existing values - something like 0.05 if !probability_field! is None else !probability_field! – om_henners Aug 8 '12 at 14:01
Thank you very much for your help!!! – user8759 Aug 8 '12 at 17:01

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