[GRASS-user] aspect map with azimuth values

GRASS GRASS user
1

Hello

how can I convert aspect map’s values to azimuth values?
or is there any way to create aspect map with azimuth values?

regards

Ahmet Temiz

–

Ahmet Temiz
Jeoloji Müh.
Afet ve Acil Durum Yönetimi Başkanlığı
Bilgi İşlem Dairesi Başkanlığı-CBS Grubu

Ahmet Temiz
Geological Eng.
Information Systems - GIS Group
Disaster and Emergency Management
of Presidency

2

On 2015-07-08 08:33, Ahmet Temiz wrote:

Hello

how can I convert aspect map's values to azimuth values?
or is there any way to create aspect map with azimuth values?

I think this should work (but you should double check):

if aspect <= 90, then azimuth = 90 - aspect
else: azimuth = 450 - aspect

i.e.

r.mapcalc "azimuth_aspect = if(aspect <= 90, (90 - aspect), (450 - aspect))"

Moritz

3

Moritz Lennert wrote:

> how can I convert aspect map's values to azimuth values?
> or is there any way to create aspect map with azimuth values?

I think this should work (but you should double check):

if aspect <= 90, then azimuth = 90 - aspect
else: azimuth = 450 - aspect

i.e.

r.mapcalc "azimuth_aspect = if(aspect <= 90, (90 - aspect), (450 -
aspect))"

Or:

  r.mapcalc "azimuth_aspect = (450 - aspect) % 360"

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

4

On 2015-07-09 00:51, Glynn Clements wrote:

Moritz Lennert wrote:

> how can I convert aspect map's values to azimuth values?
> or is there any way to create aspect map with azimuth values?

I think this should work (but you should double check):

if aspect <= 90, then azimuth = 90 - aspect
else: azimuth = 450 - aspect

i.e.

r.mapcalc "azimuth_aspect = if(aspect <= 90, (90 - aspect), (450 -
aspect))"

Or:

  r.mapcalc "azimuth_aspect = (450 - aspect) % 360"

Even better, thanks !

Added as a FAQ [1] and to the r.slope.aspect manual (r65553).

Moritz

[1] http://grasswiki.osgeo.org/wiki/Transform_CCW_aspect_to_azimuth

5

thank you all

On Thursday, July 9, 2015, Moritz Lennert <mlennert@club.worldonline.be> wrote:

On 2015-07-09 00:51, Glynn Clements wrote:

Moritz Lennert wrote:

how can I convert aspect map’s values to azimuth values?
or is there any way to create aspect map with azimuth values?

I think this should work (but you should double check):

if aspect <= 90, then azimuth = 90 - aspect
else: azimuth = 450 - aspect

i.e.

r.mapcalc “azimuth_aspect = if(aspect <= 90, (90 - aspect), (450 -
aspect))”

Or:

r.mapcalc “azimuth_aspect = (450 - aspect) % 360”

Even better, thanks !

Added as a FAQ [1] and to the r.slope.aspect manual (r65553).

Moritz

[1] http://grasswiki.osgeo.org/wiki/Transform_CCW_aspect_to_azimuth

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–

Ahmet Temiz
Jeoloji Müh.
Afet ve Acil Durum Yönetimi Başkanlığı
Bilgi İşlem Dairesi Başkanlığı-CBS Grubu

Ahmet Temiz
Geological Eng.
Information Systems - GIS Group
Disaster and Emergency Management
of Presidency