the "slope" output of s.surf.rst in my wgs84 lat/long projection is wrong -
it's value range is min=89.721184 and max=89.999451 and the raster looks
rubbish
a similar approach in a tmerc projection gave a good result
my fault or some bug?
below is my "procedure" listed in detail
GRASS:~ > g.region -p
projection: 3 (Latitude-Longitude)
zone: 0
datum: wgs84
ellipsoid: wgs84
north: 50:45:57N
south: 50:42:12N
west: 15:40:54E
east: 15:46:57E
nsres: 0:00:03
ewres: 0:00:03
rows: 75
cols: 121
GRASS:~ > r.info N50E015.meters_filled
+---------------------------------------------------------------------------
-+
| Layer: N50E015.meters_filled Date: Sun Sep 5 19:34:34 2004
|
| Mapset: dem Login of Creator: ziutek
|
| Location: srtm
|
| DataBase: /home/grassdata
|
| Title: ( N50E015.meters_filled )
|
|---------------------------------------------------------------------------
-|
|
|
| Type of Map: raster Number of Categories: 1594
|
| Data Type: FCELL
|
| Rows: 1201
|
| Columns: 1201
|
| Total Cells: 1442401
|
| Projection: Latitude-Longitude (zone 0)
|
| N: 51:00:01.5N S: 49:59:58.5N Res: 0:00:03
|
| E: 16:00:01.5E W: 14:59:58.5E Res: 0:00:03
|
| Range of data: min = 178.000000 max = 1594.000000
|
|
|
| Data Source:
|
|
|
|
|
|
|
| Data Description:
|
| generated by r.patch
|
|
|
| N50E015.meters_filled
|
+---------------------------------------------------------------------------
-+
GRASS:~ > r.to.sites -a input=N50E015.meters_filled output=dem_sites
GRASS:~ > s.info dem_sites
NDIM=2, RTYPE = -1, NSTR=0, NDEC=1
Total sites read: 9075
Total sites outside region: 0
dem_sites read.
----------------------------------------------------------
SITES FILENAME: dem_sites
--------------
Header Information:
------------------
name dem_sites
description r.to.sites -a input=N50E015.meters_filled
output=dem_sites label='No Label'
format ||%
labels Easting|Northing|%No Label
Number of DIMENSIONS: 2
--------------------
- - MIN - - - - MAX - -
dim 1 15.682083 15.782083 Easting
dim 2 50.703750 50.765417 Northing
Type of CATEGORY information: NO CATEGORY
----------------------------
Number of DOUBLE attributes: 1
---------------------------
- - MIN - - - - MAX - -
dbl 1 682 1594 No Label
Number of STRING attributes: 0
---------------------------
TOTAL SITES COUNTED: 9075
----------------------------------------------------------
GRASS:~ > s.surf.rst input=dem_sites elev=dem_s.surf.rst
slope=dem_s.surf.rst_slp aspect=dem_s.surf.rst_asp
The number of points in sites file is 9075
The number of points outside of region 0
The number of points being used (after reduction) is 9075
Processing all selected output files
will require 84888 bytes of disk space for temp files
100%
Percent complete: history initiated
GRASS:~ > r.info -r dem_s.surf.rst
min=682.395142
max=1593.271240
GRASS:~ > r.info -r dem_s.surf.rst_asp
min=0.549078
max=360.000000
GRASS:~ > r.info -r dem_s.surf.rst_slp
min=89.721184
max=89.999451