How do I convert downloaded online topo data to elevation data?

tudor

I've downloaded some basic topo data from an area but GM doesn't seem to want to let me create an elevation grid which appears to be what I need to then export the data out as a 32-bit floating point file type.

The more obvious it is the more likely it is that I don't know or have forgotten to do it.
Tudor

bmg_bob

Hello,

Which topo data source did you download from?  When I download from USA Topo Maps, the resulting data is a raster image, and Global Mapper can't convert it to elevation data.  

Why don't you just download elevation data (ASTER GDEM, or something similar), if that is what you need?

Cheers,

Bob

tudor

Thanks for this Bob.
What was what I ended up doing it worked great.