[gdal-dev] GDAL 3.x and AutoCAD GeoTIFF georeferencing

[Even Rouault]

Kirk,

the download link doesn't work.

GDAL 3.3 will use geotiff 1.1 conventions by default when a compound CRS 
is used. You may try adding -co GEOTIFF_VERSION=1.0 to force GeoTIFF 1.0.

When reading a GeoTIFF 1.1 file, GDAL will report the compoundCRS. For 
GeoTIFF 1.0 files, you need to specify --config |GTIFF_REPORT_COMPD_CS 
YES (see https://gdal.org/drivers/raster/gtiff.html#configuration-options)|

Autocad users should ideally report that to their vendor so they add 
support for GeoTIFF 1.1 (or maybe the issue is not much the change of 
the version number, but that we stripped down the formulation of geokeys 
to the minimum to avoid specifying things twice and the risk of 
contradiction)

Even
||||

Le 07/10/2021 à 21:41, Kirk Waters - NOAA Federal via gdal-dev a écrit :
> Hi all,
> I'm finding a change in georeferencing between GDAL 2.4 and 3.x that 
> results in AutoCAD not being able to figure out where on earth a 
> geotiff should be. I don't have AutoCAD, so I'm reliant on what my 
> downstream users are telling me. These are elevation Tiffs, so they do 
> have a vertical component to the SRS and that may be where the 
> difference lies. I know it isn't up to GDAL to solve AutoCAD's lack of 
> standards adoption, but I'm wondering if anyone has come across this 
> and if there's a way to force the outputs that AutoCAD will read.
>
> Two small files are included in a zip file at 
> ftp://ftp.coast.noaa.gov/tmp/kwaters/autocad_issues.zip 
> <ftp://ftp.coast.noaa.gov/tmp/kwaters/autocad_issues.zip>. One 
> (Job640647_ches_coned.tif, made with GDAL 2.4) has georeferencing that 
> works in AutoCAD, the other was made with GDAL 3.3.1 and has 
> georeferencing that fails. Both were made with gdal_translate 
> -a_srs EPSG:3582+6360 with the difference being the version of GDAL. 
> They are not the exact same location on the ground.
>
> If I look at the files with listgeo, the older version has more tags 
> and includes the horizontal and vertical units. With gdalsrsinfo, the 
> newer one shows the more complete COMPOUNDCRS that includes the 
> vertical component.
>
> I'm hoping I don't have to go back to GDAL 2.4 for AutoCAD users. If 
> anyone has come across a solution before, I'd love to hear it.
>
> Thanks,
>
> Kirk Waters, PhD            | NOAA Office for Coastal Management
> Applied Sciences Program    | 2234 South Hobson Ave
>            | Charleston, SC 29405
>
>
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