I've downloaded some USGS DEMs from the National Map, which appear to be .adf files. I can open them in ArcMap 10.2, but I need to merge them into a single mosaic. To do this, I've created a raster catalogue inside a geodatabase file, but when I try to 'Load rasters from workspace', the files are not visible.
Not sure what to do next. The files are clearly Esri-compatible (I can load and view them individually), but the steps to create a mosaic seem unable to read the files.
Best Answer
The conversion toolbox has a tool to convert your DEM file to a raster format. Do that first, for each DEM. Then use the "Mosaic to new Raster" tool to combine them into a single file.
You'll want to be double sure each file you want to combine is in the same coordinate system/projection and the same units. I once had a particularly odd looking hillshade from a couple DEMs I merged where adjacent tiles were in feet and meters...