On Wednesday 09 January 2008 00:24, Adam Dershowitz wrote: > On Jan 7, 2008, at 7:15 PM, LeeE wrote: > > On Monday 07 January 2008 22:28, Curtis Olson wrote: > >> On Jan 7, 2008 3:51 PM, Frederic Bouvier <> wrote: > >>> If we keep the same triangle budget for every tile, we will > >>> have sparse data and > >>> features at the equator and much more than what is really > >>> needed at the poles, > >>> just because the area covered by each tile will vary greatly > >>> ( proportional to > >>> 1/cos( lat ) if my math is ok ) > >> > >> My gut feeling is that once you get up (or down) into the > >> latittudes where the tiles get significantly skinny, the > >> resolution of the available data drops of significantly. We > >> really don't have a per-tile triangle budget anyway. The only > >> place where I see this making a difference is the > >> concentration of terrain elevation points would increase, but > >> this is up in an area where we only have very low res terrain > >> data anyway. SRTM drops out beyond +/- 60 degrees latitude. > >> > >> Regards, > >> > >> Curt. > > > > Yup - I downloaded lots of SRTM data to play with in GRASS and > > above/below +/- 60 lat it isn't there. > > For the SRTM mission the shuttle was at an inclination of 57 > degrees, which I believe was the maximum that the shuttle could > reach. At that inclination it could not "see" much higher > latitudes.
Thanks for the info - I guessed the reason was something like that. Polar orbits are expensive regarding fuel because the Earth's rotation does nothing to help you get there. LeeE ------------------------------------------------------------------------- Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://ad.doubleclick.net/clk;164216239;13503038;w?http://sf.net/marketplace _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
