Dear all,
I'm writing to report a problem I noticed using r.surf.contour.
I created a DTM from contour lines, but I notice something a wrong
behaviour of the r.surf.contour resulting map.
In detail I imported with v.in.ogr a shape file describing contour lines
every 25m of altitude
Then, I converted in raster (setting a resolution of the computational
region equal to 1m), and created the DTM ( setting a resolution of the
computational region equal to 5m) with r.surf.contour.
Either plotting a profile of the DTM and creating the slope map (with
r.slope.aspect), it's evident that r.surf.contour works bad.
Here you can see the slope map, with the contour level in black, and the
position of the extracted cross section; you may notice artificial steps
mainly in corrispondence of the contour levels, instead of uniform slopes:
https://www.dropbox.com/s/7olimii9s0m21rh/slope_contourlevel.PNG?dl=0
Here you can see the DTM profile along the cross section, that shows the
irregular morphology of the created DTM
https://www.dropbox.com/s/useoxstmceyulk6/DTM_cross_section.PNG?dl=0
I tested it in GRASS 6.4.4, 7.0.3 and 7.2.0, working either in Windows
and in Linux.
I hope that the developers team could correct this malfunction.
Best regards,
Bianca
PS: The used commands:
v.in.ogr ...
g.region -p res=1
v.to.rast input=contourlevel25m type=line output=contourlevel25m
use=attr column=ELEVATION
g.region -p res=5
r.surf.contour input=contourlevel25m output=dtm_contourlevel25m
r.slope.aspect elevation=dtm_contourlevel25m slope=slope_contourlevel25m
--
Eng. Bianca Federici, PhD
Assistant Professor in Geomatics
DICCA - Department of Civil, Chemical and Environmental Engineering
Laboratory of Geodesy, Geomatics and GIS
University of Genoa
Via Montallegro, 1 - 16145 Genova ITALY
Phone: +39 010 353 2421 - Fax: +39 010 353 2546
E-mail:[email protected] -www.dicca.unige.it/geomatica/ricerca
Gter srl Innovation in Geomatics, Gnss and Gis
Spin-off of the University of Genoa
Piazza De Marini 3/61, 16123 Genova
Phone: +39 010 8694830 - Fax: +39 010 8694737 -
E-mail:[email protected] -www.gter.it
www.facebook.com/Gteronline
www.twitter.com/Gteronline
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