On Sunday 17 February 2008 09:40, Tim Moore wrote: > Curtis Olson wrote: > | On Mon, Feb 11, 2008 at 8:39 AM, LeeE wrote: > > ... > > | I think I'd suspect the 110 miles figure (if that's a > | ground level value) as well, not only because that's a lot of > | atmosphere to see through but also because of curvature. > | > | I tried a quick Google to see if I could find any > | rules/formulae for visibility due to atmospheric conditions but > | didn't hit anything. It'll be interesting if you can come up > | with rules or a formulae from your analysis of a large set of > | METAR data. > | > | > | There appears to be some strangeness (bug?) in how the OSG > | version handles the far clipping plane. It seems to set the > | clip plane somewhere beyond the maximum visibility > | (weather-wise) but it seems to also clip the sky in some > | situations when it shouldn't. Last time I poked around, it > | looked like we were setup to use OSG's automatic near/far clip > | plane mechanism with no way to override it ourselves. I > | haven't dug into OSG far enough yet to learn how to fix this. > > In OSG, the far plane is fixed at 120km; the sky is drawn at a > radius of 80km from the viewer. That sky radius may be the cause > of many of the artifacts described here; turning off depth buffer > writes when drawing the sky would be a simple fix. The scenery is > paged in out to the visibility distance from the viewer's > position at sea level, using /environment/visibility-m. The OSG > clip-plane calculation is disabled. > > I haven't had a chance to look at this in detail, but I have seen > some of the wacky high-altitude effects. One possibility for the > white sky is a problem calculating the sky color / fog color. > I'll try turning off depth buffer writes as I described above. > Does anyone have a simple way to provoke the wackiness that > doesn't involve METAR? > > Thanks, > Tim
I've increased the default visibility settings in my .fgfsrc with the following entries and values: --prop:environment/config/boundary/entry/visibility-m=6000 --prop:environment/config/boundary/entry[1]/visibility-m=10000 --prop:environment/config/aloft/entry/visibility-m=20000 --prop:environment/config/aloft/entry[1]/visibility-m=30000 --prop:environment/config/aloft/entry[2]/visibility-m=40000 and the island problem is clearly visible at 3000ft, corresponding to 20000m visibility. With the same visibility settings, the sky white-out starts occurring at ~8000ft, corresponding to a visibility of between 30000m-40000m. LeeE ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
