AnsweredAssumed Answered

Basic GTOPO30 GeoTif workflow

Question asked by Elmachi on Jul 2, 2017
Latest reply on Jul 3, 2017 by jayanta.poddar

Hi, I am trying to create a DEM for Africa from scratch using the 2000 unfinished SRTM GTopo 30 ArcSec dataset.

I have downloaded four GeoTiffs containing the whole continent area, but I am finding very hard to properly clean and mosaic the 4 images together into one single file. Is there an standard workflow to make the downloaded GeoTifs ready to work in ArcMap?


One of the downloaded files can be found at 


I don't understand why I am unable to run any tool on the original tiff files. I generally get a 9999 Error message. Today I have been able to export the GeoTif to a GeoDBS but after that I am stuck.


The things that I would like to correct are:


a) Inconsistent Extent. I imagine because the projection is "incorrect". but I am failing to understand why. Projection seems to be set to GCS_WGS84, what is incorrect here and how do I fix it?

b) Ocean elevation is set to -9999. I imagine I can fix this with the Raster Calculator and the "SetNull" function. Is it worth it?

c) Is there anything else I should be aware of when working with this particular set of SRTM data?


I would appreciate any guidance on this. Thank you for your help.