27.01.2012 23:30, John Twilley пишет:
Cubic is fine for the elevation, but it doesn't work on the landcover.
which is the problem I originally mentioned.
Jack.
--
mathuin at gmail dot com
2012/1/27 Dmitry Baryshnikov<poli...@mail.ru>:
27.01.2012 20:19, John Twilley пишет:
After retrieving the files and building VRTs from them, I run the
following gdalwarp commands:
gdalwarp -q -multi -t_srs "+proj=aea +datum=NAD83 +lat_1=29.5
+lat_2=45.5 +lat_0=23 +lon_0=-96 +x_0=0 +y_0=0 +units=m" -tr 6 6 -te
2002944 2271744 2016768 2288640 \
-srcnodata -340282346638528859811704183484516925440 -dstnodata 0
ND302HT.vrt ND302HT.tif
gdalwarp -q -multi -t_srs "+proj=aea +datum=NAD83 +lat_1=29.5
+lat_2=45.5 +lat_0=23 +lon_0=-96 +x_0=0 +y_0=0 +units=m" -tr 6 6 -te
2002944 2271744 2016768 2288640 \
-srcnodata 255 -dstnodata 11 L0102HT.vrt L0102HT.tif
The only differences between the lines are the nodata values.
Jack.
--
mathuin at gmail dot com
On Thu, Jan 26, 2012 at 22:49, Dmitry Baryshnikov<poli...@mail.ru> wrote:
27.01.2012 3:39, John Twilley пишет:
I am working with elevation and landcover data downloaded from the
USGS. I use gdalwarp to convert the data to a much smaller pixel. The
elevation data works very nicely with cubic resampling, but the only
resampling that works at all for the landcover data is
nearest-neighbor and that's very blocky. When I last worked with
landcover data, I used a majority algorithm which produced smoother
output -- but that algorithm is not implemented in gdalwarp.
I am looking over the source to gdalwarp to see how hard it is to add
a new algorithm. Other than that, though, what options are available
to me? Thanks in advance!
Jack.--
mathuin at gmail dot com
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Hi John,
That is your command line string for gdalwarp?
Best regards,
Dmitry
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Hi John,
Try to add "-r cubic" command parameter
For example:
gdalwarp -q -multi -t_srs "+proj=aea +datum=NAD83 +lat_1=29.5
+lat_2=45.5 +lat_0=23 +lon_0=-96 +x_0=0 +y_0=0 +units=m" -tr 6 6 -r cubic
-te
2002944 2271744 2016768 2288640 \
-srcnodata -340282346638528859811704183484516925440 -dstnodata 0
ND302HT.vrt ND302HT.tif
You can found additional parameters description here:
http://www.gdal.org/gdalwarp.html
I have tested -r parameter and it works.
Best regards,
Dmitry
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Hi John,
You can use resampling methods:
near: nearest neighbour resampling (default, fastest algorithm, worst
interpolation quality).
bilinear: bilinear resampling.
cubic: cubic resampling.
cubicspline: cubic spline resampling.
lanczos: Lanczos windowed sinc resampling.
And what method do you need?
Best regards,
Dmitry
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