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

[Michael Sumner]

Please provide a link to the file, or the full gdalinfo output with -stats
👌

On Fri, 18 Oct 2024, 23:16 Conrad Bielski, <conrad_bielski at yahoo.com> wrote:

> Hi Mike,
> thanks for the prompt. Looking into it, the data are DEM corrected
> latitude/longitude. A GDAL info shows it as a regular raster band: Band 1
> Block=4865x1 Type=Int32, ColorInterp=Gray
>
> How can I take advantage of VRT? That sounds like a great potential
> solution.
> Thanks
> Conrad
>
> On Friday, October 18, 2024 at 12:01:27 PM GMT+1, Michael Sumner <
> mdsumner at gmail.com> wrote:
>
>
> Check if gdalinfo sees the longitude and latitude as geolocation arrays,
> then just warp to grid you want.
>
> If they aren't auto identified this can be arranged with VRT.
>
> Cheers, Mike
>
> On Fri, 18 Oct 2024, 21:55 Conrad Bielski via gdal-dev, <
> gdal-dev at lists.osgeo.org> wrote:
>
> Hi Javier,
>
> it is not a grid. So each raster pixel is assigned the geolocation. Yes -
> if I was to extract it, that's what it could be considered.
>
> Conrad
>
> On Friday, October 18, 2024 at 11:37:28 AM GMT+1, Javier Jimenez Shaw <
> j1 at jimenezshaw.com> wrote:
>
>
> 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
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