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. > > > There doesn't seem to be any alternative source of suitable data > either so I don't see how FG can cover the poles. > > (the reason I was looking was because I was interested in the Mt > Erebus volcano - FG is quite good for looking at volcanos and other > large scale geological features from the air - at some point I'll > get together a list of volcanos and astroblemes for the 'places to > fly' section of the FG docs/wiki) > > 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
