[GRASS-user] cva run time

[Hamish]

gary wrote:
> I've been running this CVA analysis for two days straight on an AMD64 
> 4400. The sites file contains one waypoint. The raster file is at 30 
> meter resolution. I'd don't have the extents of the raster file handy,
> but the site is near the edge, so you can estimate that CVA is looking
> at a half circle 2000 meters out, which if I did my math correctly is 
> about 14k cells. No virtual memory is required as the CPU has
> 3.2Gbytes of ram.
>
> r.cva input=nev616 sites=mtstircsv2 output=mtstircva2 obs_elev=1.75
> target_elev=0.0 max_dist=2000 seed=1 sample=10.0 type=sites curvc=0.0
> 
> Does the run time seem reasonable? CVA provides no estimate of
> progress.


r.los runtime is ~exponential with number of cells in the region, I
expect r.cva has similar issues. Start out with 500x500 cells and go
finer until it takes too long to run. If I understand correctly, one of
the reasons that r.cva was written was because r.los was so incredibly
slow.


good luck,
Hamish