[GRASSLIST:628] Some questions about contours.

GRASS GRASS user
1

Hi All,

Well, I started using my .DXF tiles from the Irish Ordinance Survey. The
new computer is (Dual Processor G4) is doing the v.support with out a
problem. (It's a lot faster than my G3 Powerbook).

A question. I want to colourize the contour areas, i.e. Have the lower
elevations in green, middle elevations in yellow, and mountainous regions in
brown. How would I go about doing this. The contour layers were set up in
10s (10, 30, 70, etc.), 20s (20, 40, 60, 80, 120, etc.) and 50s (50, 100,
150, etc.). I also have spot heights, and the text labels.

BTW, is it common for contour layers to be set up in this way?

Also, I was going to use NVIZ to create 3d maps. Should I also run
v.in.dxf3d or v.in.dxf3d.sh? For future reference, can I just use
v.in.dxf3d.sh when I want to create both 2d and 3d maps?

Thanks for any help.

Kurt Springs

2

A question. I want to colourize the contour areas, i.e. Have the
lower elevations in green, middle elevations in yellow, and
mountainous regions in brown. How would I go about doing this. The
contour layers were set up in 10s (10, 30, 70, etc.), 20s (20, 40, 60,
80, 120, etc.) and 50s (50, 100, 150, etc.). I also have spot
heights, and the text labels.

This should give you the general idea:

v.to.rast input=contour output=contours
s.to.rast in=height_pnt output=height_pnt
# s.to.rast not v.to.rast is to get cat labels right
r.patch in=height_pnt,contours out=land.skel

# need to do coast seperately as you can't have a category 0,
# and v.to.rast works on category.
v.to.rast in=coastline.plus1m out=coastln.plus1m

r.patch in=land.skel,coastln.plus1m out=land.skel_plus1m
g.remove rast=coastln.plus1m,contours,height_pnt,land.skel

# mask is important for speed on area without contours! (ie sea)
r.mapcalc MASK="if(isnull(sea_mask),1,null())"

r.surf.contour -f in=land.skel_plus1m out=land_plus1m
g.remove MASK
# then fill the sea with flat 1m surface
r.mapcalc land_plus1m="if(isnull(sea_mask),land_plus1m,1)"
r.colors map=land_plus1m color=rainbow

Use 'r.colors color=rules' to set up green/yellow/brown color map
(maybe take from s.surf.rst?)

good luck,
Hamish