Hi Michael,
Thank you for your reply.
I tried now in Saga directly, where the UI seems to be easier than in
QGIS processing. When I start it, I get a "Module caused access
violation" after about 10 seconds.
Here are the settings I used:
http://webgis.uster.ch/temp/saga_reclass_settings.png
Maybe the image is too big? Width and height are each > 70000 pixels.
Are there any size limitations? Or settings to improve memory usage?
Thanks,
Andreas
Am 2014-11-17 18:19, schrieb Michael Treglia:
Hi Andreas,
Strange that you're having this error - for simple reclassifications,
SAGA is typically what I use (I agree it seems complicated and tough
to understand)
Not sure if it will be useful for you, but I've got an example in a
tutorial I produced here (as a PDF - the raster reclassify starts on
page 30).
http://mltconsecol.github.io/QGIS-Tutorial/QGIS-Tutorial/Treglia_OSOS%20Notes_V1.01.pdf
[2], though the example is for a "Simple Table", to reclassify a bunch
of values.
For your problem, I would just chose the method "Single", setting your
old value and new values appropriately, and make sure to uncheck the
box to "replace other values".
Are you exporting to a file? Or to a temp file?
Also, this is do-able in R; if you want to give that a shot, write
back and I'll send some instructions [need to re-look up my method for
that... its been a little while].
Hope that helps,
Mike
On Mon, Nov 17, 2014 at 11:02 AM, Andreas Neumann
<[email protected]> wrote:
Hi,
I have a very simple task (at least I thought it is simple), but am
not able to do it properly.
I have a grayscale tiff value where I would like to replace the
value of 249 with 255 - all other values should stay as they are.
I tried with gdal "nearblack", but nothing changed - I started a
separate email-thread about that at the gdal list.
Then I tried with the QGIS raster calculator - but it does not
support conditional syntax.
I tried with Processing and GRASS - but it would stop at 8% - the
file is quite big.
Finally I came across SAGA "Reclassify with grid value". The
dialogue is very complicated and hard to understand. After a while
it would stop with an error message telling me that Saga may not be
properly configured - but it says that it is properly installed.
Quite confusing ...
I am trying on Win7 64bit.
If the file wouldn't be so big I would try this task in The Gimp -
where it is very simple to replace one pixel values with another -
using "Select by color" and "fill with a specific color".
Any idea how I could achieve my task with GDAL, QGIS, GRASS or
Saga?
Thanks,
Andreas
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