Hi Carsten, Continuing your idea I import ASTER QA Plain file ASTGTM_..._num.tiff in my GRASS location. It show a 1 to 3 stack count which borders areas superpose with artifacts (see both images end of http://yepca.org/wp3/?p=303 ). Next steep is to verify what append if I use the stack number to correct GDEM using GRASS mapcalc (something like 'if stack layer = 3 than GDEM =+20m'). Then comparing with SRTM-DEM in a untouched forest area... Let me dream...
Thanks again Sylvain 2011/8/27 Carsten Troelsgaard <troelsgaard...@live.dk>: > Hi Sylvain > > The mystery moves to why they didn't 'fix' it in the first place. > I noted that part of the Amazon Basin has a low overall stack-count. > The QA file that follows the geoTiff-data is populated with data > (stack-numbers) in the same format (geoTiff) .. that makes it possible to > predict troubled areas. I'm not sure if your GIS-tools can incoorporate and > use the auxillery-data. > > Carsten > -------------------------------------------------------- > > Sylvain wrote: > >> Hi Carsten, >> >> It is almost certain that you are right. >> >> The chapter "C. Residual Anomalies and Artifacts GDEM" detailed >> "Artifacts Related to Stack Number Irregular Boundaries." >> - Decripiton of the "pits" is similar to more or less circular holes I >> see. The text says they "Regularity and Often Occur with high >> frequency in Virtually all ASTER GDEM tiles" and "from just a FEW >> meters to 100 meters or more." Ok >> - The large positive anomalies similar to "mole run" artifacts (p.23 >> of the text). >> - Undoubtedly the linear artifact are "step anomaly" (p. 19 text). >> >> Thank you for your comments, I'll put them on the blog to let things >> clear. >> >> Bests >> >> PS: as you assume, unfortunately, no amazon mystery reveled... >> >> Sylvain > > _______________________________________________ > Discuss mailing list > Discuss@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/discuss > > _______________________________________________ Discuss mailing list Discuss@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/discuss