I agree with Frank, this sounds like the bug that I reported (and
fixed) here:
http://trac.osgeo.org/gdal/ticket/2327
(Although it became a log of my alterations to the warper kernel,
which was well beyond the scope of the original bug.)
~Seth
On Sep 29, 2008, at 11:19 PM, Frank Warmerdam wrote:
On Tue, Sep 30, 2008 at 4:30 AM, Roger André <[EMAIL PROTECTED]> wrote:
Hi List,
I've hit the same problem twice now, and I'm pretty certain after
Round 2
that I'm not introducing it. Basically, I'm using gdal_merge.py to
mosaic a
group of low-resolution, 32-bit floating point rasters together, then
running "gdalwarp -ts xxx yyy -r cubicspline" on the mosaic to get
a higher
resolution image. I'm finding afterwards that there are linear
artifacts in
the mosaic which run vertically through the mosaic, which look like
edge
artifacts, but which are not located near the edge of either an
original
low-res tile, or the resulting high res one. I've tested the
interpolation
of a single low-res tile in the area where the artifact is present
in the
mosaic and I do not get the same results - the interpolated tile is
clear of
artifacts.
Is it possible that I'm hitting some sort of memory limit that is
causing
only a certain number of columns to be interpolated at one time,
rather than
the entire row?
Roger,
There have been some fixes to some of the gdalwarp interpolator
code in recent months, so one hint is to ensure you try the latest
"trunk" code to see if perhaps the problem is already fixed.
Second, you may want to investigate the gdal_merge.py product
carefully to ensure there aren't any bad pixels in it along the
boundaries.
Third you might try the cubic (instead of cubicspline) interpolator
to see if it gives cleaner results.
Beyond that a ticket submitted on the smallest test case that
demonstrates the problem would be appreciated.
Best regards,
--
---------------------------------------
+--------------------------------------
I set the clouds in motion - turn up | Frank Warmerdam, [EMAIL PROTECTED]
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush | Geospatial Programmer for
Rent
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