(The fix would be to create a new raster elevation dataset by converting one DEM to the units of the other DEM by multiplying by the appropriate conversion factor.) Both gtopo30 and etopo3 use meters so there is no problem using these two datasets as they are. Note that before you decide which dataset to use to “fill in the gaps”, be sure you check out the z units – in some datasets elevation is in meters and in others it is in feet. For example, I can use etopo2 data (also on the Data and Maps CD) to get the elevation values for the pixels that need them.Īlthough the etopo2 data are coarser resolution, this will be difficult to see at the scale I am mapping, especially when I further modify the data by creating a hillshade. I can fix all this if I have some other elevation data to fill in the missing interior elevation values. So we need a way to clean up the data and make them coincide. Just clipping won’t work as this won’t add the missing elevation values. In some places the elevation values are missing for inland areas, and in other places, there are elevation values outside the extent of the land area. For example, if I use gtopo30 and “countries” data (available on the Esri Data and Maps CD) to create map of the Pacific Northwest, the coastline boundaries do not coincide. Sometimes you want to use raster data, like a digital elevation model (DEM), but it doesn’t have the same exact extent as the area you are mapping.

Clip raster arcmap