[GRASSLIST:737] Re: slop map,aspect map

[H Bowman]

> for prepairing slop map and aspect map:is there any better way exept 
> : r.slope.aspect el=.....format=percent...
> then: r.report ...is completly wrong....like 8905percent ,8920
> percent......and... if somebody knows please help me

Does your elevation map have any really steep terrain (sheer cliffs)?
How does the region resolution match up with the elevation map's
  resolution?
Is the elevation map integer based or floating point? (r.info  Data Type)
Are you sure your elevation map is ok (no interspersed 0s)?


format=percent returns tan(degrees) and tan(90) is infinite..

8920% is fairly strange though. That's a 89.993 deg slope.
The most I'm seeing in my submarine canyons is about 388%

The module works fine for me using the following convention:
[GRASS 5.0.2]

1:20 grade = 2.8° climb = 5% slope
1:10   = 5.7°  = 10%
1:5    = 11.3° = 20%
1:1    = 45°   = 100%
1.5:1  = 56.3° = 150%
2:1    = 63.4° = 200%
3:1    = 71.6° = 300%
inf:1  = 90°   = inf%

This matches the r.reclass table in the man page and most road signs
I've seen ..

r.report also gives seemingly correct results for me.

As cell resolution is >0 you can't have an infinite slope, so I'm not 
sure what's going wrong with your data.

It wont't make any sense of course if you are thinking 0% is flat and
100% is vertical.


format=degrees works fine as far as I can tell.



Hamish