> On 10 Jun 2009, at 20:55, Torsten Dreyer wrote: > > The ridge_lift is now also using the SGGeodesy methods, making the > > code much > > cleaner, too. > > A word of caution - looking at the code, it seems like you're mixing > geocentric (SGGeoc) and geodetic (SGGeod) co-ordinates. I haven't > looked at the code in detail, just the cvs diff, though.
Yeah - I was hoping nobody would have noticed ;-) Here is my petty excuse: The original code uses the geodetic properties /position/XXXitude-deg for geocentric calculations of other positions by applying heading and distance and used the result as geodetic positions to get ground elevation. Since this was a quite complex formula, nobody noticed. Now, it is obvious just by looking at the class names SGGeoc and SGGeod. I will do some performance tests to see how much cpu power it costs to convert from SGGeoc to SGGeod before fetching ground elevation and I will calculate the error in the calculation of the slopes if the systems are mixed. Consequently one could ask, if spheric trigonometry is adequate for short distances up to 2000m (6500ft) or if it is acceptable that earth can be assumed to be flat for short distances. This could spare many cpu cycles at the price of small displacement of the probes. I'll check this, too. For now, there is a note in the source, that this mixture is by intention, not by accident. Torsten ------------------------------------------------------------------------------ Crystal Reports - New Free Runtime and 30 Day Trial Check out the new simplified licensing option that enables unlimited royalty-free distribution of the report engine for externally facing server and web deployment. http://p.sf.net/sfu/businessobjects _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
