Difference between two DEM (rasters) in an overlap area

This can be done using the RasterExpressionEvaluator.

What do I put in the expression to get the elevation value of A minus that of B?

If the band is 0 then A[0]-B[0].

I attached a sample workspace.

Hi @dona​, like already suggested by @nielsgerrits​ the RasterExpressionEvaluator is the right transformer for this purpose. As an addition, however: please note that the RasterExperssionEvaluator requires two rasters with the same dimensions. Please see this thread for a sample workspace.

Thanks for the template but as I have two rasters that are not the same the function is not good. My two rasters are in two different files and what I want is to calculate the difference in elevation of the two rasters in the overlapping area. 

Hi @maayke​,

Indeed, I had found this post before asking my question but I can't use the RasterExpressionEvaluator transformers only on the overlap area because I will have two rasters of the same dimension in the overlap area. Do you know how to extract the overlap area between the two rasters so that I have the same dimension and use RasterExpressionEvaluator?