[Qgis-user] Georeferencer says "Could not create destination file"

[Zoltan Szecsei]

Hi,
Re your (now bold text below) comment on jgw file.......

Simplistically, the 6 lines in a typical TFW style file represent:
1st line is left/right width and direction of pixel/cell
4th line is up/down height and direction of pixel.
5th and 6th are the coordinates (in whatever CRS) of the pixel described 
in lines 1 & 4.
So in your case:
Pixel width is positive and size 2.68 units.
Pixel height is negative and size is also 2.68 (so raster pixels are 
square).
So the coordinates in lines 5 and 6 are the position of the TOP (because 
pixel height is negative) LEFT (*because pixel height is positive) 
corner of your raster file.

Somewhere is the metadata you might find a reference as to whether the 
coordinate represents the centre of the pixel or the corner (as 
described) of the pixel - but this maybe noticeable if your image lands 
up half a pixel size "wrong" in the real world.



HTH,
Zoltan


On 2026/06/28 15:54, Greg Troxel via QGIS-User wrote:
> I am guessing this image is actually in Australia, in a rural area
> "Alice Creek Nature Refuge", west of Brisbane?
>
> I would suggest talking to the people who published this and asking them
> for the CRS.  At least trying.  I find it very puzzling that it's close
> to 3857 but not really.  I'd expect some UTM in some version of GDA, or
> some conventional grid that's TM or Lambert Conformal Conic or similar,
> analogous to the US "State Plane Coordindate System.  But maybe it's
> published for normie web mapping.
>
> When you say "without the jgw", do you mean you put the JPG file in a
> directory (without the jgw file in the directory!!) and then try to add
> the file in the georeferencer?   You can do this without having the file
> as a layer - that's what I've always done.
>
> I also suggest trying the same thing with 3.44.x, on a different
> computer if necessary to avoid messing up your installation.  I switch
> back and forth to test the in-progress qgis4 packaging, but I'm using
> pkgsrc on NetBSD and I don't know what OS you are on, so that may be
> harder.
>
>
> *The jgw file is odd. The first 4 are, AIUI, supposed to be a rotation 
> matrix between pixels and the CRS. Then the coordinates of I think the 
> upper left pixel (either center or upper left of it, don't remember).*
> Your per-pixel sizes are 2.69 (projected units per pixel, I think -
> been a while), which seems normal enough, but there are values of
>
>    -4.946801637500726e-16
>
> for the cross terms (easting for verticla change, northing for
> horizontal change).  This is effectively zero.  I would not expect it to
> be confounding.  You could try with a jgw file with those modified to
> 0.0000000000.
>
> When I look at tfw file for a US historic topo map, the first 4 values
> are:
>              2.6822400000
>              0.0000000000
>              0.0000000000
>             -2.6822400000
>
> but there is a .prj file which is the original map projection, so by
> definition it is lined up precisely.
>
> Not that my projection file could possibly be relevant to .au, but FWIW
> it's
>
> PROJCS["Polyconic",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["Polyconic"],PARAMETER["latitude_of_origin",0],PARAMETER["central_meridian",-71.5625],PARAMETER["false_easting",0],PARAMETER["false_northing",0],UNIT["Meter",1]]
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-- 

=============================================
Zoltan Szecsei GPrGISc 0031
Director, Geograph (Pty) Ltd.
GIS and Photogrammetric Services

Cape Town, South Africa.

Mobile: +27-83-6004028 (Signal, not WhatsApp)
         +36-20-3594428

www.geograph.co.za
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