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| GeoCommunity Mailing List |
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| Mailing List Archives |
| Subject: | RE: [gislist] Processing elevation grid data |
| Date: |
01/20/2004 11:35:01 AM |
| From: |
True, Cynthia D. |
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You can "select" portions of a grid with a query ([range of dem] > 100)
in the map calculator of Arc. Then process parts of a grid with the CON
statement.
Good Luck,
dt
-----Original Message-----
From: gislist-bounces@lists.geocomm.com
[mailto:gislist-bounces@lists.geocomm.com] On Behalf Of Vassil Vassilev
Sent: Tuesday, January 20, 2004 1:27 AM
To: gislist@lists.geocomm.com
Subject: [gislist] Processing elevation grid data
Dear Listers,
Few day I asked a question about methods in ArcInfo for cleaning errors
in grid data representing digital elevation models.
Many thanks to Cynthia and Christian who suggested to use free softwares
to fill the 0 values and to merge the DEM I have with other DEM
available.
The problem is a bit different.
The DEM I have do not have 0 values in itself, but sinks and peaks which
are sometimes with more then 100m. low or high than their neighbours.
The pixel size of the DEM is 23m - SRTM raw data. It is DTED format
which I convert to ArcInfo GRID using ERDAS Imagine.
I know how to fill 0 values - the problem is how to select them. Using
FILL command of ArcInfo does not gives the results I want because it
fills only very small ammount of errors - the majority of them stay.
Of course it is possible to use some filters but by this I am afraid
that I will generalize too much the relief features and the resultant
scale will be 1:100,000 rather than 1:50,000 which I desire (and for
which pixel size 23m is O.K.).
Until now I tried also some techniques of ArcView Spatial Analyst - for
example to remove those pixels which 3D-area is much more then their
2D-area
- gives good result but again not for the whole dataset.
Again I am asking you if you have experience with processing elevation
grid data in ArcInfo to clean the elevation errors. I am sending you
small jpg of the generated contours from the original data to see the
errors which I am talking about.
Thank you again,
Vassil Vassilev
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