----- Original Message ----- > On Thu, May 26, 2011 at 12:26 PM, Benjamin Ducke > <[email protected]> wrote: > >> Hm-hm. Citing from the website: > >> "The problem is that the ratio of change due to air to curvature is > >> not 1:7 (0.13), as the standard refraction coefficient suggests. It > >> is 0.325. > > > > As far as I can tell, this is a mis-understanding. The value "0.325" > > applies to radio waves. Visible light is very close to 1:7. > > What if I am interested in radio waves, not visible light, e.g. for > antenna relay positions? IMHO, that refraction coefficient should not > be hard-coded. >
Agreed. It's a settable value in r.ecurv.comp and should also be one in all GRASS modules that have refraction compensation. Ben > > > > I realize the whole discourse is somewhat "clouded". But I don't > > have access to most of the relevant literature for the time > > being, nor do I have the necessary scientific background > > Me neither. But any correction should take into account that the > observer is not necessarily a human without optical equipment > (telescope etc), but can also be some technical device, e.g. a sender > or receiver of whatever signals. > > my .2c > > Markus M > ------ Files attached to this email may be in ISO 26300 format (OASIS Open Document Format). If you have difficulty opening them, please visit http://iso26300.info for more information. _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
