The Advanced Viewshed Analysis plugin has an option for calculating intervisibility of points, and you can set a restriction of distance. Maybe you can give it a try
To speed things up, you migh want to resample your DEM to a coarser resolution. You might lose some detail, but i guess that in terms of visibility you will not get a significant number of true positives or false negatives, an it will help reducing the processing time if needed Hope this helps 2014-07-09 15:08 GMT+02:00 Bjarke Christensen <[email protected] >: > Hi > > I have point data with 1600 observations in set A and 22000 observations > in set B, plus a DEM raster with a resolution of 1.6 meters. The data cover > approximately 7000 square km. so the DEM is gigantic (but split up into > 10x10 km tiles). > > I need to calculate which points in A are visible from which points in B > (or vice versa). > > I tried running r.viewshed or r.los from the processing toolbox, to > calculate the viewshed for just one point. With a max. distance of 2.5 km, > that took six hours on my laptop. So running that as a batch for all 1600 > points in set A would take more than a year. > > But I am not really interested in the whole viewshed. For each point in A, > I only want to know if it is visible from a set of perhaps 7 or 8 points in > B that fall within a specific distance radius. > > So my question is: is there any way I can calculate line of sight between > two points or two sets of points, rather than a whole viewshed? > > Or any other way that I could speed up the calculation, so that it would > take days or weeks rather than months or years. > > (Using QGIS 2.4 and GRASS 7 beta or QGIS 2.01 and GRASS 6.4.4) > > Thanks in advance, > Bjarke Christensen. > _______________________________________________ > Qgis-user mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/qgis-user >
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