[GRASS-user] Generate DEM with point and line vector

GRASS GRASS user
1

leonidas wrote:

I need to generate a DEM using a line vector file (contours,
step=20m, some are disjoined) and also combine a second point
vector file with heights.How can I achieve that with Grass?

v.to.rast + r.surf.contour

In the contours file there is also the coastline (height=0).Will
that produce any error?

yes, please read the r.surf.contour help page carefully about
that.

the quick workaround is to use r.mapcalc to multiply your raster
input with:

r.mapcalc "contline_mult = (contlines*100000)+1"

then run r.surf.contour

then reverse the above multiplication:

r.mapcalc "dem = (contour_dem -1) / 100000"

besides that pain r.surf.contour does a really nice job.

Hamish

2

I don't know if r.surf.contour is suitable for my data because there are
disjointed contour lines and spot elevation data between contour lines. So
according to the manual of r.surf.contour:"Violating these constraints will
cause non-intuitive anomalies to appear in the output map". Is there any
other tool appropriate for my data?Unfortunately there is no time to fix the
data.

Hamish wrote:

leonidas wrote:

I need to generate a DEM using a line vector file (contours,
step=20m, some are disjoined) and also combine a second point
vector file with heights.How can I achieve that with Grass?

v.to.rast + r.surf.contour

In the contours file there is also the coastline (height=0).Will
that produce any error?

yes, please read the r.surf.contour help page carefully about
that.

the quick workaround is to use r.mapcalc to multiply your raster
input with:

r.mapcalc "contline_mult = (contlines*100000)+1"

then run r.surf.contour

then reverse the above multiplication:

r.mapcalc "dem = (contour_dem -1) / 100000"

besides that pain r.surf.contour does a really nice job.

Hamish

_______________________________________________
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user

--
View this message in context: http://n2.nabble.com/Generate-DEM-with-point-and-line-vector-tp2976281p3037948.html
Sent from the Grass - Users mailing list archive at Nabble.com.