<span style>Hi Dmitry, and thanks for your answer!š</span><div style><br></div><div style>I was actually looking at this patch earlier today, but I also wanted to see if I could solve it without patching.š</div><div style>
<br></div><div style>Will this patch be included in the official source?</div><div style><br></div><div style>Is it possible to do it the way I described in the previous mail?</div><div style><br></div><div style>Cheers,</div>
<div style>Thomas</div><br><div class="gmail_quote">On Thu, May 10, 2012 at 7:11 PM, Dmitry Baryshnikov <span dir="ltr"><<a href="mailto:polimax@mail.ru" target="_blank">polimax@mail.ru</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">
10.05.2012 19:03, tseval ÎÁÐÉÓÁÌ:
<div><div class="h5"><blockquote type="cite">
<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 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>
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</pre>
</blockquote></div></div>
Hi,<br>
<br>
You can try to use this patch to enable overviews in VRT <a 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 href="http://trac.osgeo.org/gdal/ticket/2076" target="_blank"> </a><br>
<br>
Best regards,<br>
ššš Dmitry<br>
<a href="http://trac.osgeo.org/gdal/ticket/2076" target="_blank"></a>
</div>
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