topic Re: Vertical Merging for DEMs in ArcGIS Pro Questions

Vertical Merging for DEMs

GrahamDriver — Tue, 02 May 2023 12:47:51 GMT

Hi,

I have a set of two DEMs which were created separately. In 3D they appear offset to each other. The spatial data seems fine and mosaic merging does nothing to change the offset. How can I remove this 'cliff'' and merge the DEMs smoothly together?

Re: Vertical Merging for DEMs

DanPatterson — Tue, 02 May 2023 13:57:28 GMT

Are you sure that there isn't a vertical datum issue?

Vertical datums—ArcGIS Pro | Documentation

in a pinch, you could Add/Minus the height difference if it were uniform, effectively shifting one of the rasters upwards or downward

Re: Vertical Merging for DEMs

Robert_LeClair — Tue, 02 May 2023 16:32:30 GMT

Hmmmm...I would use the Mosaic to New Raster GP tool first to create one, mosaicked raster dataset and then use that raster for any analysis and/or 3D viewing. What is the result after running the GP tool?

Re: Vertical Merging for DEMs

GrahamDriver — Fri, 05 May 2023 14:12:05 GMT

Moasic to New Raster does not work. I don't see a blend in values and when placed in elevation surfaces/ground, the raster has the same 'cliff' discontinuity.

Re: Vertical Merging for DEMs

GrahamDriver — Fri, 05 May 2023 14:33:43 GMT

Hi, The datasets are not uniform across their joining axis 😞 Shifting the raster down at a central point creates a elevation difference as you progress towards the edges

Re: Vertical Merging for DEMs

DanPatterson — Fri, 05 May 2023 21:58:10 GMT

The difference lies in how they were created, perhaps a projection or coordinate definition issue.

There is no way to resolve it without going back to the original sources.

A FocalMean run a couple of times would smooth things out but not make it very useful for analysis.