[postgis-users] Line of sight (LOS) Calculation

[Mark Wynter]

Remi - the project was almost 4 years ago, we were running Grass 6.4, and at the time r.viewshed was a module addin.
The DEM was for whole of Australia, 1 second (about 30 meter intervals).
Run time for batches of 7000 towers as a single process was about 7 hours max.
1000 towers per hr, with a max distance of up to 1km (average would have been about 500m),  was what we were consistently achieving. This is where g.region becomes very important to set the extent - and to get results very quickly.
So we’re talking no more than several seconds per view shed.
I was surprised by how fast it was.

I haven’t tested in Grass7 as I haven’t loaded the DEM - at some point I might get around to it - not a priority ATM.

Would be keen for someone else to have a go, and take the original PL/R code pattern, and up date it (e.g. so the function returns WKT).  And we share it back to the PostGIS community.

Its a neat little example of how you can embed both R and grass directly in a PostGIS workflow.   So rather than the temptation of trying to do everything in PostGIS, you now have R and grass at your fingertips, still within the comforts of PostGIS.

WDYT?

> Very cool solution !
> 
> Could you give a better estimate of run time?
> (example of DEM resolution, time?)