11.05.2012 11:50, Thomas Sevaldrud написал:
10.05.2012 23:14, Thomas Sevaldrud написал:
Hi Dmitry, and thanks for your answer!
Hi Thomas!
I was actually looking at this patch earlier today, but I also
wanted to see if I could solve it without patching.
Will this patch be included in the official source?
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.
Is it possible to do it the way I described in the previous mail?
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.
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?
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.
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.
- Thomas
Cheers,
Thomas
On Thu, May 10, 2012 at 7:11 PM, Dmitry Baryshnikov
<poli...@mail.ru <mailto:poli...@mail.ru>> wrote:
10.05.2012 19:03, tseval написал:
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 :)
--
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Hi,
You can try to use this patch to enable overviews in VRT
http://trac.osgeo.org/gdal/ticket/2076
or waits as I accomplish my work on fixing this
situation.<http://trac.osgeo.org/gdal/ticket/2076>
Best regards,
Dmitry
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Best regards,
Dmitry
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