[GRASS-dev] r.los scales badly

[Peter Hopfgartner]

Hi,

I've done some time measurements with r.los.

Basically I'm working on a DTM raster of Austria derived from SRTM data.

Thus, the region has a native res of 90m and has 2224 rows and 2228 columns.

If I'm doing a r.los after g.region -pa res=360 it takes 1.719 s to 
complete the calculation (time taken through the time command). With 
res=180, res=120, res=90 I get the following table:

res  t (s)
---   --------
360     1.72
180     17.96
120    123.68
 90    688.37

It scales very badly. Is this expected? Are there better algorithms for 
calculating LOS then that used in r.los?

Regards,

Peter