Hi Pedro, On Thu, May 7, 2020 at 4:03 PM Pedro Venâncio <[email protected]> wrote: > > Hi, > > I'm trying the new gdal_viewshed and it is in fact really quick! But the > result is completely different than other viewshed analysis algorithms: > > https://cld.pt/dl/download/e80216bb-d7eb-40b0-b6da-8e45572e9eb3/viewshed.jpg > > https://cld.pt/dl/download/ee993a0b-cf86-462a-b831-307aecde7865/viewshed2.jpg > > GRASS and Visibility Analysis plugin for QGIS have almost the same result. > The result from gdal_viewshed seems completely overrated. The options I'm > using are [almost] the same in both algorithms. > > gdal_viewshed -b 1 -md 28000.0 -ox -41597.922 -oy 71254.049 -oz 21.6 -tz 10.0 > -vv 1 -cc 0.85714 -f GTiff path_to_mdt.tif path_to_output.tif >
Does -tz 10.0 in effect raise your DEM target elevation by 10 units? Was the same done in GRASS and the Visibility Analysis plugin for QGIS? Was the observer height of -oz 21.6 the same for all three as well? Best regards, Eli > Has anyone else this experience? > > Thanks! Best regards, > Pedro Venâncio > > > Howard Butler <[email protected]> escreveu no dia quinta, 7/05/2020 à(s) 17:41: >> >> >> >> > On May 7, 2020, at 11:05 AM, Eli Adam <[email protected]> wrote: >> > >> > The image with two dots makes me think that there can be multiple >> > observer inputs. Is that the case? Is the syntax for that just to >> > keep adding more -ox, -oy, (and oz)? For instance, gdal_viewshed -md >> > 500 -ox -10147017 -oy 5108065 -ox -10147117 -oy 5108165+100 source.tif >> > destination.tif >> >> The picture is a poor example. You can't do multiple obvservers, but you can >> run a bunch of masks together and then merge to get a multipoint viewshed. I >> indeed made two masks with gdal_viewshed and then merged them together to >> make that picture. >> >> That picture or the docs should maybe be updated to reflect a more common >> scenario with better description. File a ticket and attach some language and >> pictures to it as you start playing with it and we can merge it. >> >> Thanks, >> >> Howard >> _______________________________________________ >> gdal-dev mailing list >> [email protected] >> https://lists.osgeo.org/mailman/listinfo/gdal-dev > > _______________________________________________ > gdal-dev mailing list > [email protected] > https://lists.osgeo.org/mailman/listinfo/gdal-dev -- Eli L Adam, PLS Lincoln County Surveyor's Office 880 NE 7th Street Newport, OR 97365 541-574-1289 _______________________________________________ gdal-dev mailing list [email protected] https://lists.osgeo.org/mailman/listinfo/gdal-dev
