[gdal-dev] [help][gdalwarp]Use of gdalwarp with data overlapping antimeridian

[Robert Coup]

Hi Christophe,

What do you *expect or want* to happen with your images?

Are your 4326 image coordinates in -180° to +180° range (ie. the right
longitude is < the left); or do they go past +180°?

3857 is a projected coordinate system, so doesn't have a builtin concept of
wrapping. Some clients implement.
Do you want x values >20037508.34? But they'll only display on the "right"
side of the world then (if at all).

The simplest approach is likely to be to do two warp operations, for the
left and right parts, ending up with two images — one with
left=-20037508.34 and one with right=+20037508.34

Rob :)


On 1 March 2018 at 15:23, LAVOYE Christophe <Christophe.LAVOYE at akka.eu>
wrote:

> Hello,
>
>
>
> I’m using GDAL library in a C# project.
>
>
>
> To reproject some geotiff files i’m calling gdalwarp tool as external
> process with this command:
>
>
>
> gdalwarp.exe -s_srs EPSG:4326 -t_srs EPSG:3857 -dstalpha input.tiff
> output.tiff
>
>
>
>
>
> All works fine except for data overlapping antimeridian such as the
> associated tiff file.
>
>
>
> I don’t find how fix my problem or if I’m using the correct tool for those
> kind of data.
>
>
>
>
>
> Best regards,
>
>
>
>
>
> [image: cid:image003.png at 01D1FD34.3B7C8CC0]
>
> *Christophe LAVOYE - **Analyste*
> * AKKA Technologies *Informatique & Systèmes
> 7 boulevard Henri Ziegler – 31700 BLAGNAC
> Tél : +33 (0)5 36 25 15 40 <+33%205%2036%2025%2015%2040>
> Email : christophe.lavoye at akka.eu
>
>
>
>
>
> _______________________________________________
> gdal-dev mailing list
> gdal-dev at lists.osgeo.org
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>



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