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: [email protected] To: [email protected] CC: [email protected]; [email protected] 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 <[email protected]> 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 <[email protected]>: 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 _______________________________________________ Qgis-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/qgis-user
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