[gdal-dev] JPEG file with ESRI world file .jpgw but geotransform not established

Even Rouault even.rouault at spatialys.com
Sun Jan 26 16:45:07 PST 2020

Hi Markus,

I've found some doc about this .jgwx in
So this is a ESRI specific thing
"""Starting at ArcGIS 9.2 SP2, if the transformation cannot be expressed as a 
world file, the Update Georeferencing command on the Georeferencing toolbar 
writes the transformation into the .aux.xml file and also writes an 
approximate affine transformation into a text file or a world file with an x 
on the end of the extension name. [...]. Keep in mind that this is not an 
exact transformation; it is only an approximation."""

So it might not be always relevant to report the content of the .jgwx as a 
geotransform. Or if we did, we should probably add some metadata like 

> Using the graphical GPC tool of GRASS GIS
> (https://grass.osgeo.org/grass78/manuals/wxGUI.gcp.html)
> and exporting the map to GeoTIFF + gdal_translate to JPG with World
> file I obtained a quite similar result with working geotransform:

How does this tool manage to create a geotransform frmo this file ? The 
.aux.xml file does contain a GeodataXform ESRI specific element. GDAL just 
extract this in the xml:ESRI metadata domain, but doesn't do further use of 
this. Here it could potentially report the GCPs in it as GDAL GCPs. I've 
grepped in GRASS source code to see if it has specific code to extract GCPs 
from GeodataXform, but I can't find anything. So this is quite mysterious to 


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