[Gdal-dev] Merging DEMs seamlessly

[Ben Discoe]

Chris,

In my experience, merging USGS DEMs _always_ leaves tiny gaps.  That's why
merging data in the GDAL-based VTP software always includes a "fill gaps"
operation to do simple interpolation to fill those gaps for you.

For more info, http://vterrain.org/Doc/VTBuilder/overview.html

VTBuilder has seen heavy use by many people for many years because
unattended elevation processing, besides being highly un-visual, so often
runs into these sorts of problems.

-Ben

> -----Original Message-----
> From: Frank Warmerdam
> Sent: Tuesday, June 06, 2006 6:32 AM
> 
> Chris Pennock wrote:
> > Merging DEMs is a frequent topic, but the suggestion I often see is 
> > like:
> > gdal_merge.py -o merged.tif dem1.dem dem2.dem
> > 
> > I when this is done, even if the two DEMs being merged have 
> > the *same* corner points, I usually get a few points of empty
> > space between the dems in the merged tif.
> > 
> > Does anyone have any thoughts on why this would happen, or 
> > a possbile fix?
> 
> Chris,
> 
> Can you provide a couple of DEM files which demonstrate this problem?
> And what version of gdal_merge.py you are using?  There were 
> some adjustments made to try and address edge-effects some months ago.