[Qgis-user] QGIS 3.10.1A Geotiff Coordinate Transform Problem

[Stewart Holt]

I have QGIS 3.10.1 installed and I can no longer display historic USGS
geofiffs. I probably have not used these since at least version 3.8. I got
a message saying that the transform could not be done. The file had a CRS
that was apparently user generated (automatically) based on NAD27. I have
over 50 of these files and each seems to have a different User CRS. The
project CRS is EPSG:3857.

The transform failure message provided a link to download the grid shift
file ntv2_0.gsb. I clicked the link which downloaded a zip file. I
extracted only  ntv2_0.gsb from it and browsed to it using the "Install
ntv2_0.gsb from Folder..." button. It installed with a message indicating
success. I closed and reopened the project as directed, and selected the
geotiff file layer. There was no error but the canvas was obviously far
from the rest of my project (SE US). I zoomed to the geotiff layer and
selected the Google satellite view. I zoomed out until I recognized the
area as being northern Africa. Approximate center coordinates
were: 32.78461469, -0.00187768.

The projection file GA_Hightower Bald_245924_1988_24000_geo.tif.prj
contains this:

PROJCS["Transverse_Mercator",GEOGCS["GCS_North_American_1927",DATUM["D_North_American_1927",SPHEROID["Clarke_1866",6378206.4,294.9786982]],PRIMEM["Greenwich",0],UNIT["Degree",0.017453292519943295]],PROJECTION["Transverse_Mercator"],PARAMETER["latitude_of_origin",0],PARAMETER["central_meridian",-83.56299999999918],PARAMETER["scale_factor",1],PARAMETER["false_easting",0],PARAMETER["false_northing",0],UNIT["Meter",1]]

Previously, I had not even downloaded the .prj files because QGIS seemed to
handle the geotiff files with no problem. I tried downloading the tfw and
prj files but it made no difference. I also tried to set the CRS for the
geotiff based on the prj file and that gave the same result.

I think that after installing the grid shift file, there is no error
detected but the transformation fails.

Has anyone had any experience with USGS geotiff files and QGIS 3.10.1?

A download link for the files above is:
ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Maps/HistoricalTopo/GeoTIFF/GA/

Any help to solve this would be appreciated.

Thanks,

Stewart Holt
Georgia Appalachian Trail Club
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