> You mentioned earlier that a lot of the performance issues would > disappear > if we could probe the terrain 100 times faster. I've been thinking about > this for a while for ai traffic, skyop's moving map instrument, and > weather. > > I'm thinking of storing some resolution of altitude data in the tile > itself, > making altitude queries very fast at the expense of a larger tile (in > memory and disk). > > I'm just starting the work, but I would like any feedback on the idea.
I can maybe tell you what I need. Currently, Local Weather uses terrain info in three ways: 1) a presampling routine gets gross features in the vicinity of the aircraft, i.e. mean altitude, median altitude, max. altitude,... That's now implemented by Torsten as C++ routine running in the background - I don't know details and don't know if it would benefit 2) convective clouds are placed based on both terrain type and elevation. For convective (not any other) clouds, there is extra work running for 2-30 seconds (dependent on number, terrain detail,...) in the background at the rate of ~12 geodinfo() calls per frame (geodinfo is a rather expensive operation - more than 25 per frame are simply out of the question). 3) for the 3rd generation cloud-terrain model currently under development, there's an additional need to probe elevation (but not terrain type) for many cloud types - curently using geodinfo() as well 2) and 3) are among the most computationally intensive processes Local Weather runs, simply because geodinfo() is expensive (though perhaps not the most garbage-collection triggering ones). If that could be made much faster, tile setup could be accelerated dramatically. I wouldn't actually need the exact altitude/terrain type at a given location for weather - an approximation which gets me some elevation and terrain type within, say, 100 m of the specified coordinates would be just as good, especially if it comes faster. If it really accelerates by a large margin, then it allows the setup of tiles to be essentially in a single frame, so one can really restart the system without the user noticing. Cheers, * Thorsten ------------------------------------------------------------------------------ AppSumo Presents a FREE Video for the SourceForge Community by Eric Ries, the creator of the Lean Startup Methodology on "Lean Startup Secrets Revealed." This video shows you how to validate your ideas, optimize your ideas and identify your business strategy. http://p.sf.net/sfu/appsumosfdev2dev _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
