Re: [Qgis-user] Eliminate GAPS SRTM 30 metros

Thu, 28 Jan 2016 05:33:01 -0800 

Hi, 
Thank for that data link. I did not know about it.  I am currently doing a 
PhD on various publicly available  DEMs in Canada.  My research 
focuses in  Canada because SRTMs are more precise in the north and south 
(tighter orbit, more data, leaf off).  All this is better for the SRTM 
radar.   I should have more results in about one month and I will 
submit my results for publication.  Hopefully, I will also have the latest 
NASA DEM is my study as they should be publish in June. 
So far, SRTM 30 and 90m  have about haft the error of aster gdem2.  
There is not much loss with the 90 m srtm but the 90 m pixel does suffer in 
mountainous regions. Most of the error from the ASTER data is cause clearly by 
the tree cover.  The SRTM radar has a good vegetation penetration in 
Canada (leaf off).  Aster is made from near infra red images and therefore 
has no canopy penetration. But radar is generally smother partly because 
smoothing is part of the data noise reduction in radar images.  ASTER has 
a sharper image resolution even if the pixel size is the same size but this 
comes at the expense of extra noise. 
I will be happy to communicate more result as I get them. 
Nicolas Cadieux M.Sc. 
Les Entreprises Archéotec inc.  
8548, rue Saint-Denis Montréal H2P 2H2 
Téléphone: 514.381.5112  Fax: 514.381.4995 
www.archeotec.ca 
On Jan 28, 2016 02:49, "Thomas Götzelt-2 [via OSGeo.org]   " 
<[email protected]> wrote: 

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Hi,
ALOS World 3D - 30m (AW3D30) data may be also considered an
alternative ( http://www.eorc.jaxa.jp/ALOS/en/aw3d30/ ), for the time
being already available for substantial parts of Southern Asia and
South America. Informations on how resolution and error margins of the
dataset compare to ASTERDEM or SRTM30 will be appreciated.
Cheers
Thomas
Am 27.01.16 um 21:35 schrieb Nicolas Cadieux:
> Hi, Aster gdem are not as good with about 7 m error. They are
> clearly canopy level models.  They cover up to 83d and srtm
> are south and north of 60d only.  They are more detailed. 
> Nicolas Cadieux M.Sc. Les Entreprises Archéotec inc.  
> 8548, rue Saint-Denis Montréal H2P 2H2 
> Téléphone: 514.381.5112  Fax: 
514.381.4995 
> www.archeotec.ca On Jan 27, 2016 2:38 PM, "Carlos Cerdán [via
> OSGeo.org] " < [hidden email] >
> wrote: Hi Eddison: Try r.fillnulls from Processing or directly in
> GRASS. So, we have 30 m SRTMS in http://www2.jpl.nasa.gov/srtm/   .
> It'll be interesting to compare with ASTER GDEM Cheers
> 2016-01-27 13:25 GMT-05:00 Eddison Araya < [hidden email] >:
> <blockquote style="border-left:2px solid 
#cccccc;padding:0
> 1em" style="margin:0 0 0 0.8ex;border-left:1px #ccc
> solid;padding-left:1ex"> Hola, how eliminate gaps in SRTM
> 30 meters?, in QGIS see no data areas (gaps). Thank you 
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