Bernd and Matt: thank you very much for answering.
still the ideas are quite confused but your help gave a chance for
understanding ;)
any further suggestion from other users is well accepted!
all the best,
Nic
Date: Wed, 15 Oct 2014 12:24:09 +1100
Subject: Re: [Qgis-user] NoData
From: mattsli...@gmail.com
To: bernd.vogelges...@gmx.de
CC: qgis-user@lists.osgeo.org; sciurusurba...@hotmail.it
I can contribute a couple of things from my experience with some of these.1.
there are some gotchas with using NULL (in vector files) is that the result of
X+NULL or X concatenate NULL, effectively any operation using NULL the result
is NULL. This is expected/deliberate.I've only come across Nan in tiffs when
there's somethings wrong with the format / import.Nodata seems to be specified,
the default is set at 0 on most files/formats I've dealt with (usually single
band rasters) and its handled the same way as if I specify -999.
Matt
On Wed, Oct 15, 2014 at 10:39 AM, Bernd Vogelgesang <bernd.vogelges...@gmx.de>
wrote:
This post seemes to have drowned, so I dare to bump it, hoping that some less
confused people like me might anwser to it.I'm using QGIS for years now, but I
never figured out how that stuff is supposed to work.One of the reasons why I
try to do a lot of stuff now in R is that NA is NA !
Am 08.10.2014, 11:27 Uhr, schrieb Niccolò Marchi <sciurusurba...@hotmail.it>:
hi all!
please, is there someone who could explain properly all the "NoData topic"?
I mean:
1. differences in setting negative values (-999, -9999, -3.40282e +35, etc) VS
NoData (Nan, NoData, NULL)
2. how QGIS handles it
3. "best practices" or good hints for managing them
sorry but I've quite a big confusion.
Thank you very much in advance!
Nic
-- Bernd Vogelgesang
Siedlerstraße 2
91083 Baiersdorf/Igelsdorf
Tel: 09133-825374
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