[R-sig-Geo] testing DEM geoprocessing in RSAGA, SAGA GIS and ARCGIS: different of results in value range

[Alexander Brenning]

It seems that SAGA GIS stores angles (slope, aspect) in internally 
radian, but it shows them in degrees when displaying them in the GUI of 
SAGA GIS. I noticed that once in the context of slope angles and was 
pretty puzzled... just do *180/pi to convert radian into degree.
   A.



gianni lavaredo wrote:
> Dear Professor,
> 
> Thanks for your competence and your work in RSAGA and Rypgeo. This packages
> are very useful and interesting.
> 
> I am testing different geoprocessing code in RSAGA, SAGA, Phyton and Rypgeo
> to see the results, but I noticed a singular situation. I am using this code
> to create SLOPE and ASPECT with DEM in RSAGA and see the difference in
> ARCGIS geoprocessing
> 
> rsaga.slope("DEM","SLOPErad")
> # convert to slope in percent:
> rsaga.grid.calculus("SLOPErad","SLOPE", formula="100*tan(a)")
> rsaga.sgrd.to.esri("SLOPE", prec = 4)
> rsaga.aspect("DEM","ASPECT")
> rsaga.sgrd.to.esri("ASPECT", prec= 4)
> 
> but there are some difference when I convert the ASPECT.sgrd in ASCII file.
> ex
> 
> ASPECT.sgrd: min value=  0.020869 max value =  360.00001
> (the same Value range I have in SAGA GIS or in ARCGIS)
> 
> ASPECT.asc: min value= 0.0004 max value= 6.2832
> 
> Thanks Again
> 
> Gianni
> 

-- 
Alexander Brenning
brenning at uwaterloo.ca - T +1-519-888-4567 ext 35783
Department of Geography and Environmental Management
University of Waterloo
200 University Ave. W - Waterloo, ON - Canada N2L 3G1
http://www.fes.uwaterloo.ca/geography/faculty/brenning/