topic Re: Raster Calculator Subtraction problems in ArcGIS Spatial Analyst Questions

Raster Calculator Subtraction problems

ErnestDunwoody — Tue, 07 Jun 2011 12:36:32 GMT

Hello,

All of a sudden my Raster Calculator returns nonsense values for any expression with a subtraction in it. Just installed ArcGIS10 SP2. Related? Don't know.

I narrowed the problem down to the subtraction function. All other math functions seem okay. Math Minus tool works okay.

Anyone else with this problem? Any ideas for a solution?

Appreciate any help anyone can offer.

Edi

Re: Raster Calculator Subtraction problems

DanPatterson_Retired — Tue, 07 Jun 2011 16:01:10 GMT

Do you have an example?
I have come across some operands that don't work unless the operation preceding the operand (and after) is not enclosed in round brackets. For example:

Con(("polynom2" == 5) & ("logistic" == 5), 1, 0)

Re: Raster Calculator Subtraction problems

ErnestDunwoody — Wed, 08 Jun 2011 08:20:54 GMT

Hello Dan,

Thank you for your reply. I worked on it some more and found the following. (Note this was not a problem in ArcGIS10 with only SP1 added.)

Using ArcGIS Modeller, when you drag the layers from the Table of Contents to the Model window and then perform a subsequent operation that includes a Minus (-) the results are that all pixels have a "0" value.

However, if you add the layers for the analysis using the Model Add "+" icon the calculation proceeds corectly. Likewise convert the model to a tool and add the layers by using the Browse button and the model runs correctly. Don't recall testing draging the layers to the tool fields.

So, I just have to remember not to drag layers to the Model window unless ESRI comes up with a fix.

Sincerely,
Edi