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11.05.2012 11:50, Thomas Sevaldrud ΞΑΠΙΣΑΜ:
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cite="mid:CAJSDX1jZxb0fL7XdQaLUm+fpfTr_3c0JZMXNqR53Sn=9N+5KTw@mail.gmail.com"
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<div class="h5">10.05.2012 23:14, Thomas Sevaldrud
ΞΑΠΙΣΑΜ:
<blockquote type="cite">Hi Dmitry, and thanks for your
answer! <br>
</blockquote>
Hi Thomas!
<blockquote type="cite">
<div><br>
</div>
<div>I was actually looking at this patch earlier
today, but I also wanted to see if I could solve it
without patching.</div>
<div><br>
</div>
<div>Will this patch be included in the official
source?</div>
</blockquote>
My patch needs some refactoring and testing on python
bindings. The work is going on , but not so fast as I
wish. As I finished and commit my code, It'll be some
testing period and than fixes will be accepted.<br>
<blockquote type="cite">
<div><br>
</div>
<div>Is it possible to do it the way I described in
the previous mail?</div>
</blockquote>
Yes, you can try to warp and overview images (bands).
You can get an overview of needed level from
GDALRasterBand Class via GetOverview (int) method, but
than you need to work on band basis and mixed them in
colour image by yourself.<br>
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<div>This is probably a stupid question, but I couldn't find it
anywhere in the documentation. How do I create a GDALDataset
from a set of existing GDALRasterBands?</div>
<div><br>
</div>
<div>I guess I could copy the pixel data with the RasterIO
methods, but I was hoping I could make a VRT or something from
a set of existing overview bands and then do the warping on
this, to avoid the copying of a potentially huge dataset.</div>
</div>
</blockquote>
I don't sure 100% but you can play with VRTDataset. Look at this
method: GDALAddBand and VRTAddSimpleSource. Maybe CreateVRTSeparate
method from apps\gdalbuildvrt.cpp will be helpful.<br>
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<div>- Thomas</div>
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<div> </div>
<div>Cheers,</div>
<div>Thomas<br>
<br>
<div class="gmail_quote">On Thu, May 10, 2012 at
7:11 PM, Dmitry Baryshnikov <span dir="ltr"><<a
moz-do-not-send="true"
href="mailto:polimax@mail.ru" target="_blank">polimax@mail.ru</a>></span>
wrote:<br>
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10.05.2012 19:03, tseval ΞΑΠΙΣΑΜ:
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<pre>Hi,
I'm trying to cut and reproject a large image with overviews using the c++
api. This runs extremely slow when I produce highly downsampled cutouts
covering large areas of the original image.
I understand the the Warp API doesn't use the overviews when resampling, so
I wanted to make a temporary dataset from one of the downscaled overviews
and do the warping on this dataset instead.
First of all, is this a sensible way of doing things? If so, what driver
should I use? I guess VRT? I have been trying to create a VRT by doing
something like this:
double scaleX = (double)ovrW/origW;
double scaleY = (double)ovrH/origH;
GDALDataset* vrtDS = vrtDriver->Create("", ovrW, ovrH, _numBands,
_dataType, NULL);
GDALSetProjection(vrtDS, _srcProjectionWKT);
double geoTransform[6];
srcDS->GetGeoTransform(geoTransform);
geoTransform[XFM_PIXEL_SIZE_EW] = scaleX*geoTransform[XFM_PIXEL_SIZE_EW];
geoTransform[XFM_PIXEL_SIZE_NS] = scaleY*geoTransform[XFM_PIXEL_SIZE_NS];
vrtDS->SetGeoTransform(geoTransform);
But how am I supposed to set the bands in the VRT from the downscaled
overview bands in the original image?
Any help on this would be greatly appreciated :)
--
View this message in context: <a moz-do-not-send="true" href="http://osgeo-org.1560.n6.nabble.com/Creating-a-VRT-dataset-from-overviews-in-C-tp4965891.html" target="_blank">http://osgeo-org.1560.n6.nabble.com/Creating-a-VRT-dataset-from-overviews-in-C-tp4965891.html</a>
Sent from the GDAL - Dev mailing list archive at Nabble.com.
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</pre>
</blockquote>
</div>
</div>
Hi,<br>
<br>
You can try to use this patch to enable
overviews in VRT <a moz-do-not-send="true"
href="http://trac.osgeo.org/gdal/ticket/2076"
target="_blank">http://trac.osgeo.org/gdal/ticket/2076</a><br>
or waits as I accomplish my work on fixing
this situation.<a moz-do-not-send="true"
href="http://trac.osgeo.org/gdal/ticket/2076"
target="_blank"> </a><br>
<br>
Best regards,<br>
Dmitry<br>
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<br>
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</blockquote>
Best regards,<br>
Dmitry<br>
<br>
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