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 http://glcfapp.glcf.umd.edu:8080/esdi/ftp?id=68196 

 

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.

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