[Qgis-user] Error of "Cannot Use Project Transform..."

[Nyall Dawson]

On Thu, 13 Feb 2020 at 12:16, Michael Treglia <mtreglia at gmail.com> wrote:
>
> Hi All,
>
> Using QGIS 3.10.2 on Windows x64, installed via OSGeo4w.
>
> When opening a .qgz file with data in ESRI code 102008 and the project in EPSG 4326, I get a warning - "Cannot use project transform between ESRI:102008 and Unknown CRS"
>
> Upon clicking the Details button, a window pops up - "Project Transformation Not Available", with the full text pasted at the end of the email. There is also a link to download and button to install the "Grid Shift File"
>
> I wanted to check if there was a big change from 3.4 to 3.10 that deprecates certain types of transformations or something, that now requires these grid shift files to specifically be installed. I know there have been some major broader changes with gdal and such, but this issue does not happen with version 3.4.15.  As much as anything, I'm just thinking about what might come up in future workflows, as 3.10 becomes the LTR.

In this case, the original user who created the project has specified
that for that project, the NA83SCRS.GSB must be used when transforming
between ESRI:102008 and EPSG:4326. You've then opened that project on
a system which doesn't have this grid shift file installed, so you get
the warning to advise you that things won't be showing/calculating as
the original project creator intended.

This particular file is available from the archive at
https://download.osgeo.org/proj/proj-datumgrid-north-america-latest.zip

Nyall

>
> Thanks so much for any insights, and for your time. Best regards,
> Mike
>
>
> Full message from Project Transformations Not Available Box:
>
> This project specifies a preset transform between ESRI:102008 - North_America_Albers_Equal_Area_Conic and Unknown CRS: GEOGCRS["unknown",DATUM["unknown",ELLIPSOID["WGS 8…, which is not available for use on the system.
>
> This transformation requires the grid file “NA83SCRS.GSB”, which is not available for use on the system.
>
> The operation specified for use in the project is:
>
> +proj=pipeline +step +inv +proj=aea +lat_0=40 +lon_0=-96 +lat_1=20 +lat_2=60 +x_0=0 +y_0=0 +ellps=GRS80 +step +inv +proj=hgridshift +grids=NA83SCRS.GSB +step +proj=aea +lat_0=40 +lon_0=-96 +lat_1=20 +lat_2=60 +x_0=0 +y_0=0 +ellps=GRS80
>
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