[gdal-dev] gdal.AutoCreateWarpedVRT returning different results than osr.CoordinateTransformation

[Billy Newman]

Ok I think I get exactly what you are saying.

Dataset dataset = // image file dataset in wrong projection
Dataset epsg4326Dataset = gdal.AutoCreateWarpedVrt(....);
double[] geoTransform = epsg4326Dataset.GetGeoTransform();
// grab out the corner point in epsg:4326

So doing that won't actually warp the image right?  Only creating virtual
warped points when you ask for them?

Thanks again for all the help, I really appreciate it.

Billy

On Sat, May 5, 2012 at 4:40 PM, Frank Warmerdam <warmerdam at pobox.com> wrote:

> On 12-05-05 02:22 PM, Billy Newman wrote:
>
>> Still very confused.
>>
>> I have a tiff file.  I want to get the metadata for that tiff but in
>> EPSG:4326,
>> without actually warping the image.  I can use CoordinateTransformation
>> to do
>> this, but again it gives me different results than gdalwarp.
>>
>> I will use gdalwarp later (realtime) to serve out an image.  But if the
>> metadata I store (from CoordinateTransformation) is different than the
>> metadata
>> when I warp I will run into problems.
>>
>> gdalwarp gives something like minLon = 30.300001234, but
>> CoordinateTransformation gives minLon = 30.29988787.  I want to gdalwarp
>> number
>> but without actually warping the entire image.
>>
>> I am not sure what .vrt file you are talking about.
>>
>
> Billy,
>
> The subject line of this thread is about AutoCreateWarpedVRT().  I'm
> talking
> about the VRT created by it.  Note that creating the VRT does not actually
> do any work to warp the image - it just create a description of how the
> warp would be done in the form of a pseudo-dataset - a VRT.
>
>
> Best regards,
> --
> ------------------------------**---------+--------------------**
> ------------------
> I set the clouds in motion - turn up   | Frank Warmerdam,
> warmerdam at pobox.com
> light and sound - activate the windows | http://home.gdal.org/warmerda
> and watch the world go round - Rush    | Geospatial Software Developer
>
>
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