[GLIMS] GDEM2 coming-- much better than GDEM1

[Jeffrey Kargel]

Adina,
I am not doing the validating, and I doubt that the validation is being done over glaciers (though it might be). At this point I think all we can do is let the validators do their work, and then let the system release the product.  There's nothing we can do to speed it up or ease out more details. I know Bob Crippen well, I know his work well, and his style.  The excerpt of his email is all I know, other than some other comments that pertained to individual people and the authors of the GDEM algorithms, and it didn't make sense to circulate those comments. When Bob says it is much better, I would think that is understated if anything. But I don't know any more about it.  One thing that Bob worked hard on with GDEM1 was tracking down the causes and finding a nearly perfect fix for the pit and cone artifacts. Those apparently are much reduced, which was the #1 biggest problem with GDEM1. However, Bob has a nearly perfect fix for that problem (well, just perfect identification of where the errors are and then infilling with SRTM, which is not perfect), and it is clear that Bob's fix was not incorporated into the GDEM2 algorithm, which is too bad. Apparently August (maybe late August) is the expected release time.  So not far away. In my group, we are just continuing to use GDEM 1 where it has use and not putting anything on hold waiting for a better product. We don't have long to wait if you want to wait for some of your DEM applications.  (But the GLIMS Book will necessarily be a GDEM1 generation thing, since we have to push it along.)
--Jeff

> Date: Thu, 14 Jul 2011 10:38:04 -0600
> From: racovite at colorado.edu
> To: jeffreyskargel at hotmail.com; GLIMS at nsidc.org
> Subject: Re: [GLIMS] GDEM2 coming-- much better than GDEM1
> 
> Jeff-
> 
> Thanks for this note. I'd be curious what "better" means, as it sounds
> qualitative to me. Better vertical accuracy? better terrain
> representation? The higher resolution usually introduces more noise in
> the DEM, it will be interesting to compare. Any way we can get more
> detail? I would imagine all of us will start validating in our study
> areas, but it would be nice to know about the results of this initial
> validation so we don;t duplicate efforts.
> 
> cheers
> Adina
> 
> 
> 
> 
> On Mon, Jul 11, 2011 at 5:13 PM, Jeffrey Kargel
> <jeffreyskargel at hotmail.com> wrote:
> > Dear all,
> > Here is an encouraging word from somebody who is validating GDEM2; he is
> > about as capable an evaluator is you will find anywhere, so his
> > encouragement is notable.  He says:
> > "GDEM2 looks a lot better than GDEM1 — higher resolution and far, far fewer
> > glitches.  ... ... GDEM2 is a great improvement over GDEM1." He notes some
> > remaining issues where clouds contaminated the results, so wariness will
> > still be warranted.
> > GDEM2 may be available possibly in about 6 weeks. So if you are using GDEM1,
> > or gave up using it, please keep GDEM2 in mind.
> > --Jeff
> >
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> >
> >
> 
> 
> 
> -- 
> **********************************************
> Adina Racoviteanu
> 
> Institute of Arctic and Alpine Research
> 1560 30th St, UCB 450
> University of Colorado at Boulder
> Boulder, CO 80309
> Ph:(303)-492-5546, Fax (303)-492-6388
> email: Adina.Racoviteanu at colorado.edu
> http://snobear.colorado.edu/Adina
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