AI-GEOSTATS: Again: Variograms or Kriging for Digital Elevation Models Analysis and regularization ?
- Dear AI-Geostats members,thanks for your reply !
> An interesting question. You can, of course look at the entiredistribution
> of errors, rather than just the summary stats. I would recommend doingthat
> just to know wether the error is normally distributed for example.I already looked in detail at the distribution of height differences and
found a gaussian distribution, but shifted with an offset. This is ok,
because I compare a Digital Surface Model (optical data) with a terrain
model. I also separated my DEM heights into objectclass-related heights with
a classification layer, because i.e. imaging and matching trees will give
the height of the trees, rather than the terrain height. But I only found a
trend for expected 'tree' and 'building' height offsets (speaking of
comparing it with a digital terrain reference model).
What I want to know is: Is it possible to find something like the 'level of
information content' or 'level of structured detail' .
Also a measure of the quality of the regularized heights, because I have
this sparse and dense point distribution...some heights are calculated with
a dense neighbouring distribution, some with a sparse. As a pre-processing
step I should somehow get a measure of 'expected interpolation accuracy' or
something like that. The interpolation is done within a defined search
window and using all available height in all octants with a weighted
distance fuction. The a moving average plane will do the interpolation.
That's just a short description of hwo it works.
> error distribution obtained within a window. Finally, why not estimate theautocorrelated.
> variogram of the difference? This will tell you whether the error is
Unfortuately I don't have any experience in obtaining variograms and don't
know if I can analyse such a large amount of data points (> 100000). If you
have a hint on that, that would be useful !
Thanks and best regards,
Dipl.-Ing. Rainer Mueller
German Aerospace Center - DLR Oberpfaffenhofen
Remote Sensing Technology Institute
Image Science - Photogrammetry Phone : +49 (8153) 28-2872
PO Box 1116 FAX : +49 (8153) 28-1444
82230 Wessling -GERMANY-
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