Weighted Overlay Extent

[MatthewTwietmeyer]

Hello,

I am in the first stage of a suitability analysis for subsurface soil/groundwater. I am trying to combine two raster datasets one being a smaller extent raster of clay soil depth and one way larger groundwater depth raster. I want the two to combine with equal influence to create a raster extent that includes the clay raster layer values combined with ground water but keeps the values of the larger ground water layer that don't intersect the clay layer's extent for later stages of the suitability analysis, but I want the extent to be of the larger raster dataset and not limited to just what is within the smaller extent clay raster. I keep running the model and I continue to get the smaller extent combination regardless if I change the environmental settings of the extent to be the larger extent or union of the two inputs. Is the weigted overlay tool limited to certain processing extents? Or should I be using a different spatial analysis approach for these two rasters?

Thanks,

Matt

[curtvprice · Accepted solution]

This isn't about processing extent. If you go into the ArcMap layer symbology and symbolize your NoData with a color symbol, you'll see that your grids are coming out full extent, but your result cells are NoData if any of the input cells at that location are NoData.

For most operators, including Weighted Overlay, if any of the inputs are NoData, the output for that cell is NoData.

The solution is to use Raster Calculator to reclassify your NoData cells to something that will carry through your analysis, for example, zero.  You can do this after you run your weighted overlay too.

The following Raster Calculator expression will replace all NoData cells with zero over the current extent (by default, Union of Inputs = the extent of "in_raster"):

Con(IsNull("in_raster"), 0, "in_raster")

Hope this helps.