[GRASS-user] cva run time

[gary]

I was hoping that setting max_dist to be small would reduce the data. 
Otherwise, I need to figure out how to truncate my DEM.

Hamish wrote:
> 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
> 
>