I use PDF as well, there you can not save a background-color or
something like that.
This should be better an option in QGIS to "set the colors of the black
recangles" ;-)
thanks all.
Am 01.10.2021 um 23:19 schrieb Nicolas Cadieux:
Hi,
It's quite simple, you just need to set the nodata
Hi, I usually do a brief adjustment on pixel values prior to
georeferencing, to make sure that no pixel has the value I need to assign
to nodata.
Depending on the source dataset, I usually try to replace the zeros with
ones, and reserve the zero for nodata.
El vie, 1 de oct. de 2021 a la(s)
Hi,
It's quite simple, you just need to set the nodata value (what you call
the background-color) in the original file and then save it. The
complication is that this requires that the datatype for the file
accepts the no data value. This part is harder to figure out for your
not used to
sounds like rocketscience ... for a simple task to set the
background-color ...
may be I am searching the web where I have to place my feature request
for this ...
Am 01.10.2021 um 21:39 schrieb Nicolas Cadieux:
Hi,
Start by setting the nodata value in the input raster.
Hi,
Start by setting the nodata value in the input raster.
(raster/conversion/translate/Assign a specific nodata value to output
bands). Make sure you select a data type that allows your nodata
value. For example, if you select Byte - Eight bit unsigned integer,
and a no data value of
Hi,
nope this isn't what I want ... it is the same as setting transparent
color manually.
I am using PDF and TIF for georeferencing.
Regards
Without no-data-0 or transparent-color:
Set transparent-color to 0,0,0 or use no-data-0:
Am 01.10.2021 um 19:26 schrieb Charles Dixon-Paver:
I just
I just loaded an unreferenced png with black content into qgis, then set
the nodata value to 9, then did a fake georeference with arbitrary
coordinates, and the result seemed to be rotated without any background
pixels. Using 3.20 on Windows. The geoereferencer has a checkbox for
setting
When georeferencing, aren't the areas
outside the original image, eg, the "triangles" resulting from
rotation, treated as no data? Wouldn't this issue be resolved by
setting the no data value to something other than black?
Just guessing here, obviously.
yes, maybe to orange, a color that is not in the original image, so I
can do this color transparent.
Am 01.10.2021 um 18:25 schrieb David Strip:
When georeferencing, aren't the areas outside the original image, eg,
the "triangles" resulting from rotation, treated as no data? Wouldn't
this
Hi,
Perhaps you can add a file or a screen shot because what you want to do it not
clear. An image would help. In your second email, you talk about triangles?
Did you mean to write rectangles?
Nicolas Cadieux
https://gitlab.com/njacadieux
> Le 1 oct. 2021 à 05:30, L.W. a écrit :
>
>
> I
Maybe this has to do with this longstanding issue:
https://github.com/qgis/QGIS/issues/23760
Regards,
Roland
Gesendet: Freitag, 01. Oktober 2021 um 11:30 Uhr
Von: "L.W."
An: "Charles Dixon-Paver"
Cc: "qgis-user@lists.osgeo.org"
Betreff: Re: [Qgis-u
I think one of us is on the wrong track with what is to be achieved.
I don't want to manipulate the image itself, just the background at the
moment when the raster image (or raster pdf) is converted to a TIF and
georeferenced.
if the rectangle contains black text, as described, this would also
You can translate pixel values with the raster calculator (available under
the raster menu). Black pixels will have a value of 0,0,0 on RGB bands and
red pixels would have a value of 255,0,0 so it's just a matter of changing
the values accordingly on those bands.
The raster calculator will
Thanks for answering, but I think this is not the way I want to go ...
Or, I do not have written detailed.
I have a raster image e.g. a white rectangle, after setting the points,
QGIS rotats this image, let's say, by 45 degrees.
The corners of the imported image are now black triangles.
I do
There's not really any way for a GIS system to automatically differentiate
between black background pixels and black data pixels. QGIS supports users
setting custom pixel values to render as transparent pixels, but it's left
up to users to ensure that their data and background values are
Hi,
how to change the backgroundcolor of a georeferenzed raster image?
When a raster image is rotated by qgis after setting all points the
backgroundcolor is black RGB(0,0,0).
Set black to transparent is difficult when there is black text.
regards
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