how to merge DEM rasters

Discussion created by AudraLindsey76 on Feb 14, 2013
I have many (46) DEM tiles that I want to merge so that I can create one large TIN -it's a large county in NW Alberta.  I have tried creating Raster Dataset (intending then to load the rasters into it), I have tried mosaic to New Raster.  It will mosaic to new raster but the output raster has a constant value, each pixel is "255".  WHAT am i doing wrong and how do I get this to work before my trial times out in 9 days?  I thought that maybe I had to symbolize each raster the same way but that isn't it. I can't find the right process and there is no how-to other than the python script listed in the Help.