[gdal-dev] Reprojecting image with lat/lon bands - best practice?

Even Rouault even.rouault at spatialys.com
Fri Oct 18 20:44:16 PDT 2024


Le 18/10/2024 à 23:32, Michael Sumner a écrit :
>
> I didn't know you could do that with -to!! That's awesome
>
> 🤟
>
Hum, sorry for giving a wrong track, it seems the newly LLM module 
implemented in my brain has hallucinated...

So you have rather to create a geoloc.vrt file with

gdal_translate input.tif geoloc.vrt -b 2 -b 1

and then;

gdal_translate input.tif imagery.vrt -b 3

gdalwarp imagery.vrt imagery_warped.tif -geoloc -to 
GEOLOC_ARRAY=geoloc.vrt -a_srs EPSG:4326  -overwrite

>
> On Sat, 19 Oct 2024, 05:01 Even Rouault via gdal-dev, 
> <gdal-dev at lists.osgeo.org> wrote:
>
>     Conrad,
>
>     Try something like:
>
>     gdal_translate input.tif imagery.vrt -b 3
>
>     gdalwarp imagery.vrt imagery_warped.tif -geoloc -to
>     X_DATASET=input.tif -to X_BAND=2 -to Y_DATASET=input.tif -to
>     Y_BAND=1 -to PIXEL_OFFSET=0 -to PIXEL_STEP=1 -to LINE_OFFSET=0 -to
>     LINE_STEP=1 -to SRS=EPSG:4326 -a_srs EPSG:4326  -overwrite
>
>     Obviously I have most certainly got something wrong in the above,
>     but hopefully with a tiny tweaking that should put you on the
>     right track.
>
>     Reference:
>     https://gdal.org/en/latest/development/rfc/rfc4_geolocate.html
>
>     Even
>
>     Le 18/10/2024 à 12:37, Javier Jimenez Shaw via gdal-dev a écrit :
>>     Is it an actual grid? in the meaning of having constant step size
>>     in X and Y.
>>     In that case the geolocation is just the corner and the x and y
>>     sizes. You can convert to a georeference raster, and warp it.
>>     If it is not the case, you have something more like a 2D
>>     pointcloud, or a bunch of poins in a strange vector format.
>>
>>     On Fri, 18 Oct 2024 at 12:20, Conrad Bielski via gdal-dev
>>     <gdal-dev at lists.osgeo.org> wrote:
>>
>>         Hello GDAL-experts,
>>
>>         normally when I use GDAL for reprojecting imagery, the
>>         projection information that I use is the source spatial
>>         reference (SRS) associated with the imagery. However, now I
>>         have imagery which is lat/lon geographic and I have two
>>         separate bands which also carry the pixel geographic
>>         information. So the following raster inputs all the same size:
>>         1. Band 1 = latitude
>>         2. Band 2 = longitude
>>         3. Band 3 = imagery
>>
>>         The question I have is how best to integrate this information
>>         into a reprojection workflow?
>>
>>         I presume that gdalwarp is the best option here, but how can
>>         I take advantage of the individual pixel location information
>>         (rather than just the extents for example)? I know that I can
>>         mosaic into an existing file that I have already created in
>>         the target projection. Is this the best way to apply gdalwarp
>>         in this context?
>>
>>         I'm just wondering what is the best way to integrate the
>>         lat/lon pixel information into my warping using gdalwarp.
>>
>>         Thanks in advance for your help,
>>         Conrad
>>         _______________________________________________
>>         gdal-dev mailing list
>>         gdal-dev at lists.osgeo.org
>>         https://lists.osgeo.org/mailman/listinfo/gdal-dev
>>
>>
>>     _______________________________________________
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>>     gdal-dev at lists.osgeo.org
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>
>     -- 
>     http://www.spatialys.com
>     My software is free, but my time generally not.
>     Butcher of all kinds of standards, open or closed formats. At the end, this is just about bytes.
>
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-- 
http://www.spatialys.com
My software is free, but my time generally not.
Butcher of all kinds of standards, open or closed formats. At the end, this is just about bytes.
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