[GRASS-user] howto make my srtm-dem jump the GIS gap

[William Kyngesburye]

On Aug 9, 2006, at 4:51 AM, Rudolf Maurer wrote:

> Will try William and Macieks r.out.gdal suggestions, but did not do  
> it yet.
> When I export TIF I am losing the height data, right?
>
That's why you use the Int16 data type, so it can store the full  
range of elevations.  So it only works for integer elevations.   
Floats would need another method, like the ascii grid export from  
GDAL.  Or scaling the data up a number of decimal places so an  
integer could be used.

> I spotted an online document on SRTM-Data which mentioned the  
> direct import of SRTM-Data using the Spatial Analyst extension.
> Do I need this for importing the GRASS-made Grid-Files, too?
>
I don't think the Spatial Analyst extension has anything to do with  
raster conversion, just extra analysis functions.

> 2006/8/8, David Finlayson < david.p.finlayson at gmail.com>:
> I use r.our.arc frequenctly to transfer data between ArcGIS and  
> GRASS. What exactly is the problem you are having?
>

When I think back on it, I believe the reason I had no luck with  
ascii/arc grid export is that I needed to transfer HUGE rasters over  
to Arc, and Arc choked on the multi-GB text files.  I think an ascii  
grid under 2GB could work.  There's a lot of expansion in a text  
file, so the grass raster size limit would be smaller.

And, it might not have even been such a hard limitation, more a  
matter of principal - I just didn't want to copy a multi-GB file over  
the network when there must be a better binary way, and zipping,  
copying, unzipping a huge file doesn't save much time.

-----
William Kyngesburye <kyngchaos at kyngchaos.com>
http://www.kyngchaos.com/

All generalizations are dangerous, even this one.