Martin Spott wrote: >Hmm, do M$F$ and X-Plane use different ellipsoids for their scenery ? >To my understanding as long as both use an international acknowledged >reference system like WGS84, then there should not be the requirement >for a reference point. >Everything in FlightGear that relates to landcover schema is WGS84 and >I assume the SRTM elevation data is as well - did I miss something ? > >
The issue is that the specific elevation of a specific point on the earth can be different between sims. Consider Sim "A" that flattens airports to they are a single consistant elevation across the entire airport surface. Now contrast that with Sim "B" that lets airport surfaces generally follow the lay of the land so that the runways have realistic humps and depressions as you look down their length. Now, when an aircraft is at ground level in Sim "A", it won't be exactly at ground level in Sim "B". Sim "C" might have a different idea of the exact ground level across the surface of an airport. Now if all of these simulators participate in a multiplayer environment, aircraft taxiing along the ground in one sim, will probably always be too high or two low in the other two sims. One resolution is to force all simulators to use the exact same scenery model. Another possible solution would be to transmit height above ground. But this could be very computationally intensive to resolve into an actual altitude for the clients and some sims may not have that capability. Also, what happens if the reference point on the 747 in Sim "A" is a different place that the 747 in Sim "B"? The main problem here is when aircraft from other simulators taxi around airports. Unfortunately, this is one of the most interesting things to look at. FG could perhaps come up with a heuristic for deciding when an aircraft has WOW and force it to ground level. Again, that could begin to cost us computationally if there are many aircraft to adjust, but it's something we could do if we wanted to. Curt. -- Curtis Olson http://www.flightgear.org/~curt HumanFIRST Program http://www.humanfirst.umn.edu/ FlightGear Project http://www.flightgear.org Unique text: 2f585eeea02e2c79d7b1d8c4963bae2d _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
