I'm trying to merge 24 DEM files, 24 DEM
after applying the tool (Mosaic to New Raster) only 11 out of the 24 merged. New Raster
All the original files are in the same projection, pixel type, band, etc. I also tried DEM to raster tool first before using Mosaic to New Raster and the results were the same.

4 Answers 4


This is a common ArcGIS problem. I believe as you zoom-in some of the areas that seem not to be there begin appearing as if it was a rendering issue...

I think, although it has never been confirmed, that it most often happens when mosaicing tiles from File Geodatabase (FGDB) sources and outputting the mosaic raster to the same or other File Godatabase.

My crude workaround is to import the individual source tiles into a File Geodatabase but when mosaicing output the result into a folder as ESRI Grid. When complete import back into FGDB.

I have most success using this approach but also had it fail a few times. When it does, I try mosacing from individual ESRI Grid files and output to an ESRI Grid. When all fails i try the reverse, and so on.

Sounds strange but works for me.

  • You were right it was all there, just needed to zoom in. Thanks!!!
    – Omega
    Sep 4, 2014 at 19:34

Create a mosaic dataset, right-click your new dataset and choose "Add Rasters", navigate to your folder containing your rasters, click OK.


Usual thing for this tool. Try replacing it by few mosaicing, say working in 'columns', i.e. repeat it 6 times plus one


I tried this solution of mosaicing to a folder instead of FGDB, it worked for some of my projects but still had gaps in others. After further experimentation, I found that recalculating the pyramids to 0 for all the raster tiles first, then mosaic to new raster, was successful in creating the full mosaic without gaps. Possibly a combination of this plus mosaicing to a folder is the magic combo.

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