[GRASSLIST:9189] Color shaded relief

GRASS GRASS user
1

Hi all,

I'm wondering if anyone out there has had experience creating
attractive color shaded relief images from DEMs. The basic procedure I
have used is as follows:

1) r.shaded.relief DEM azimuth=270 altitude=30
2) d.his h_map=DEM_shadei_map=DEM

This is the procedure suggested in Markus' book. My problem is that
I always end up with rather muddy-looking results. I have tried all
kinds of variations on this procedure, including different altitude
settings, recoloring the hillshade with a contrast-enhancing
greyscale color scheme before running r.his, etc. No real
improvement. As an example of what I'm shooting for, have a look at
this:

http://www.srh.noaa.gov/ridge/grk.shtml

Can anyone suggest a technique for achieving this quality?

- Jason

Jason Horn
Boston University Department of Biology
5 Cumington Street Boston, MA 02215

jhorn@bu.edu
office: 617 353 6987
cell: 401 588 2766

2

Jason, the method I generally use is similar to yours with some slight changes. I am pretty happy with my results, but each person has their own tastes naturally.

Using r.shaded.relief, set your altitude to a higher angle, I typically use 60.
Your color map is important. I use the following color map for maps with topography and bathymetry.
8200 255 255 255
7000 255 252 225
5000 252 245 193
4000 252 237 147
3250 250 231 105
2000 177 157 72
230 70 120 50
0 0 82 30
-1 255 255 255
-511 211 227 237
-915 152 218 235
-1519 127 255 255
-2165 204 255 255
-2722 224 251 255
-4200 33 163 255
-5800 38 57 224
-6500 148 33 255
-10799 0 0 0

You can set this (or another color scheme) to your map by first copying and pasting this table into a file (make sure to preserve UNIX carriage returns). Then use
cat your_file | r.colors color=rules map=DEM

then use d.his h_map=DEM i_map=DEM.shade

g'luck
-Ian

On Nov 22, 2005, at 1:59 PM, Jason Horn wrote:

Hi all,

I'm wondering if anyone out there has had experience creating
attractive color shaded relief images from DEMs. The basic procedure I
have used is as follows:

1) r.shaded.relief DEM azimuth=270 altitude=30
2) d.his h_map=DEM_shadei_map=DEM

This is the procedure suggested in Markus' book. My problem is that
I always end up with rather muddy-looking results. I have tried all
kinds of variations on this procedure, including different altitude
settings, recoloring the hillshade with a contrast-enhancing
greyscale color scheme before running r.his, etc. No real
improvement. As an example of what I'm shooting for, have a look at
this:

http://www.srh.noaa.gov/ridge/grk.shtml

Can anyone suggest a technique for achieving this quality?

- Jason

Jason Horn
Boston University Department of Biology
5 Cumington Street Boston, MA 02215

jhorn@bu.edu
office: 617 353 6987
cell: 401 588 2766

>
What happens if a big asteroid hits Earth? Judging from realistic simulations involving a sledge hammer and a common laboratory frog, we can assume it will be pretty bad.
  - Dave Barry

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3

A couple things to keep in mind. As Ian MacMillan, you can exercise a lot of
control over the color table of the draping map.

Also, there are several ways to control the creation of the shaded relief
map. Besides changing the altitude of the sun (lower makes more shadows and
accentuates relief), you can also change the z-exaggeration of the relief.
It is set by default to 1, but I often change it to 2 (double the apparent
relief).

Attached is a small jpeg example of what you can do.

Michael

__________________________________________
Michael Barton, Professor of Anthropology
School of Human Evolution and Social Change
Arizona State University
Tempe, AZ 85287-2402

phone: 480-965-6213
fax: 480-965-7671
www: http://www.public.asu.edu/~cmbarton

From: Jason Horn <jhorn@bu.edu>
Date: Tue, 22 Nov 2005 16:59:58 -0500
To: GRASS Users List <GRASSLIST@baylor.edu>
Subject: [GRASSLIST:9189] Color shaded relief

Hi all,

I'm wondering if anyone out there has had experience creating
attractive color shaded relief images from DEMs. The basic procedure I
have used is as follows:

1) r.shaded.relief DEM azimuth=270 altitude=30
2) d.his h_map=DEM_shadei_map=DEM

This is the procedure suggested in Markus' book. My problem is that
I always end up with rather muddy-looking results. I have tried all
kinds of variations on this procedure, including different altitude
settings, recoloring the hillshade with a contrast-enhancing
greyscale color scheme before running r.his, etc. No real
improvement. As an example of what I'm shooting for, have a look at
this:

http://www.srh.noaa.gov/ridge/grk.shtml

Can anyone suggest a technique for achieving this quality?

- Jason

Jason Horn
Boston University Department of Biology
5 Cumington Street Boston, MA 02215

jhorn@bu.edu
office: 617 353 6987
cell: 401 588 2766

(attachments)

polop_cam_studyarea1.jpg

4

Dear Jason,

I may have done a mistake in the syntax.

1) r.shaded.relief DEM azimuth=270 altitude=30
2) d.his h_map=DEM_shadei_map=DEM

- Jason

Try for the hue parameter the very DEM map and for intensity the derived shaded
relief.

d.his h=DEM i=DEM_shade

Miha Staut

___________________________________________________________
Yahoo! Model Search 2005 - Find the next catwalk superstars - http://uk.news.yahoo.com/hot/model-search/

5

Learn from the Master of shaded relief:

http://www.shadedrelief.com/

Tom Patterson makes us all look like rank armatures.

David

On 11/23/05, David Finlayson <dfinlays@u.washington.edu> wrote:

Learn from the Master of shaded relief:

http://www.shadedrelief.com/

Tom Patterson makes us all look like rank armatures.

David

On 11/22/05, Miha Staut <mihastaut@yahoo.co.uk> wrote:
> Dear Jason,
>
> I may have done a mistake in the syntax.
>
> > 1) r.shaded.relief DEM azimuth=270 altitude=30
> > 2) d.his h_map=DEM_shadei_map=DEM
> >
> > - Jason
>
> Try for the hue parameter the very DEM map and for intensity the derived shaded
> relief.
>
> d.his h=DEM i=DEM_shade
>
> Miha Staut
>
>
>
> ___________________________________________________________
> Yahoo! Model Search 2005 - Find the next catwalk superstars - http://uk.news.yahoo.com/hot/model-search/
>
>

--
David Finlayson
Marine Geology & Geophysics
School of Oceanography
Box 357940
University of Washington
Seattle, WA 98195-7940
USA

Office: Marine Sciences Building, Room 112
Phone: (206) 616-9407
Web: http://students.washington.edu/dfinlays

--
David Finlayson
Marine Geology & Geophysics
School of Oceanography
Box 357940
University of Washington
Seattle, WA 98195-7940
USA

Office: Marine Sciences Building, Room 112
Phone: (206) 616-9407
Web: http://students.washington.edu/dfinlays

6

Jason Horn wrote:

I'm wondering if anyone out there has had experience creating
attractive color shaded relief images from DEMs. The basic procedure I
have used is as follows:

1) r.shaded.relief DEM azimuth=270 altitude=30
2) d.his h_map=DEM_shadei_map=DEM

This is the procedure suggested in Markus' book. My problem is that
I always end up with rather muddy-looking results. I have tried all
kinds of variations on this procedure, including different altitude
settings, recoloring the hillshade with a contrast-enhancing
greyscale color scheme before running r.his, etc. No real
improvement. As an example of what I'm shooting for, have a look at
this:

http://www.srh.noaa.gov/ridge/grk.shtml

Can anyone suggest a technique for achieving this quality?

I don't see how the results produced by r.shaded.relief and d.his are
any worse than that example.

Have your elevation maps been subject to smoothing? A shaded relief
map will only look as crisp as the actual terrain.

--
Glynn Clements <glynn@gclements.plus.com>

7

Micheal,

Thanks for the tips. I have found that exaggerating the z factor has helped somewhat. What i'm most interested in is how you got your results to look so saturated and bright. I find that when combining the dem map (hue) with the shade map (intensity) using d.his, I end up with very muddy results because every color is darkened by some level of grey from the greyscale shade map. I'd love to see the original shademap you used and the color table that got you those results. I'm impressed.

- Jason

On Nov 23, 2005, at 2:09 AM, Michael Barton wrote:

A couple things to keep in mind. As Ian MacMillan, you can exercise a lot of
control over the color table of the draping map.

Also, there are several ways to control the creation of the shaded relief
map. Besides changing the altitude of the sun (lower makes more shadows and
accentuates relief), you can also change the z-exaggeration of the relief.
It is set by default to 1, but I often change it to 2 (double the apparent
relief).

Attached is a small jpeg example of what you can do.

Michael

__________________________________________
Michael Barton, Professor of Anthropology
School of Human Evolution and Social Change
Arizona State University
Tempe, AZ 85287-2402

phone: 480-965-6213
fax: 480-965-7671
www: http://www.public.asu.edu/~cmbarton

From: Jason Horn <jhorn@bu.edu>
Date: Tue, 22 Nov 2005 16:59:58 -0500
To: GRASS Users List <GRASSLIST@baylor.edu>
Subject: [GRASSLIST:9189] Color shaded relief

Hi all,

I'm wondering if anyone out there has had experience creating
attractive color shaded relief images from DEMs. The basic procedure I
have used is as follows:

1) r.shaded.relief DEM azimuth=270 altitude=30
2) d.his h_map=DEM_shadei_map=DEM

This is the procedure suggested in Markus' book. My problem is that
I always end up with rather muddy-looking results. I have tried all
kinds of variations on this procedure, including different altitude
settings, recoloring the hillshade with a contrast-enhancing
greyscale color scheme before running r.his, etc. No real
improvement. As an example of what I'm shooting for, have a look at
this:

http://www.srh.noaa.gov/ridge/grk.shtml

Can anyone suggest a technique for achieving this quality?

- Jason

Jason Horn
Boston University Department of Biology
5 Cumington Street Boston, MA 02215

jhorn@bu.edu
office: 617 353 6987
cell: 401 588 2766

<polop_cam_studyarea1.jpg>