On Mon, Aug 1, 2011 at 9:48 AM, James Turner wrote: > > On 30 Jul 2011, at 20:31, Stuart Buchanan wrote: > >> So, I quickly wrote an alternative to the current Nasal system geodinfo(), >> using the groundcache instead of the current scenery method. > > I'm working on a new (C++) navigation display instrument, which I hope to add > a proper EGPWS terrain display layer too - replacing Skyop's Nasal version, > with his full and happy consent :) > > I already reviewed the ground cache code, but I wan't sure how performant it > would be, to scan the ND range (eg, 80, 160 or 320nm) at, say, 10 or 50m > intervals. The problem is the EGPWS needs relative altitude to the aircraft, > but in real-life the update isn't instantaneous, especially at longer ranges, > so I expect to perform the scan incrementally over a few seconds.
In both cases, are you not going to be limited by what tiles have been loaded? I did a further test just going in a straight line for 4 degrees in 0.001 degree increments, but only picked up some 400 points before both methods just start returning 0 elevation due to there being no tile loaded. FTR, I was seeing around 0.8s to make the 4000 queries using the old method, 0.045s with the new, so it's significantly faster in that case as well. -Stuart ------------------------------------------------------------------------------ BlackBerry® DevCon Americas, Oct. 18-20, San Francisco, CA The must-attend event for mobile developers. Connect with experts. Get tools for creating Super Apps. See the latest technologies. Sessions, hands-on labs, demos & much more. Register early & save! http://p.sf.net/sfu/rim-blackberry-1 _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
