Hi. I've been thinking of ways in which I could help out with stuff for FlightGear, given that I don't code in C++. Other than providing useful bug reports and the occasional odd suggestion, I thought of getting my feet wet by working on adding taxiways to airports that aren't currently given them. I also thought I might look at airport buildings, taxiway markers, etc., and at 3D structures for landmarks such as are present in the San Francisco scenery.
If it's at all worthwhile for me to do this, then I have some questions. 1. Regarding adding taxiways, I read a bunch of old emails on this list, and it seems like there's two ways to approach this. One is David Luff's TaxiDraw, which (as I understand it) is solely concerned with rendering taxiways, and produces a table of taxiway information for a particular airport that's in an appropriate format for insertion into the Airports/runways.dat file. The other is fgsd-taxi, a modified fgsd that produces taxiway layouts not for rendering, but for AI aircraft to follow. Do I have this correctly? If so, does it make sense when doing the former to do the latter, even if the AI is not yet fully implemented, thinking that then it doesn't have to be added later? 2. The taxiways that *are* listed in the Airport/runways.dat, typically for major airports, don't have taxiway identifications listed. For example, A KSQL 5 CYN San Carlos R KSQL 12 37.511856 -122.249524 138.09 2599 75 NARHN NYVN 0 0 NYVN 0 0 T KSQL xxx 37.511303 -122.249374 134.68 2600 75 YCB T KSQL xxx 37.510796 -122.250015 134.68 2600 75 YCB T KSQL xxx 37.511108 -122.251083 134.68 2000 200 YCB According to the explanation of the format on Robin Peel's site, those "xxx" should give a taxiway identifier. I presume that FlightGear doesn't use them at the present; but I can imagine that they might be in the future, for ATC or AI, or for default taxiway signs (in the absence of signs placed as 3D models in the scenery). If these are known, such as through an airport chart, should they be put in? If so, in what format (e.g. left-justified, right-justified, zero padded, etc.)? 3. Where should the taxiway data go? The TaxiDraw tutorial mentions sending them to Robin Peel, for inclusion in the complete airport data. Is that still the case? Various things I've read in the archives here gave me the impression that these days, FlightGear is compiling its own airport data files from the DAFIF, rather than getting them from Robin Peel's compilation. The fact that the files in Airport/* are similar to, but not exactly the same as, those described on Robin Peel's website, seem to support that perception. Is that true? If it is, then where should the taxiway info be sent to, so FlightGear can use it? 4. Is the information in the airport files considered to be 100% accurate? I occasionally see differences between runway lengths listed in runways.dat and those listed in other sources, such as U.S. state Department of Aviation databases, or U.S. FAA references (reproduced at airnav.com). The differences are rarely large -- less than 20 feet typically -- but it makes me wonder what's right and whether there may be other discrepancies and so on. 5. My understanding is that at this point, the runways, taxiways and aprons are drawn using stock textures for the appropriate type of surface specified in runways.dat. Is that correct? Just out of curiosity, how difficult is that to change on very small scales, e.g. for a particular small area at a particular location at a particular airport. I can imagine putting in eye candy like stains and skidmarks and gate markings and stuff like that, such as one sees in images like: http://virtual.planepictures.net/show.cgi?18008 http://library.avsim.net/sendfile.php?SendImage=48658 http://virtual.planepictures.net/show.cgi?22698 How straightforward would that be to integrate such things into scenery? I wouldn't think it'd be too consuming of rendering resources, but maybe it would? 6. What about abandoned airstrips? Not closed runways, but airports that don't even truly exist anymore, but can still be seen from the air. There's a website at http://members.tripod.com/airfields_freeman/ where a pilot gives info about these things in the US.. I think it'd be cool to be able to see these from the sky, have them available for emergency touchdowns, etc. But I'm not sure whether anyone else thinks that's a good idea, or what the best way of implementing them would be (e.g just a model placed on the terrain at a given point, or with their own listings in runways.dat, or whatever). 7. Are there any guidelines for maximum complexity of 3D models for scenery? On one hand, I want to make cool things. But OTOH, I don't want to make things which are so cool that they won't get used because they're too apt to drag framerates down into the dirt. That'll do for starters. Thanks for any info you can give; hope my input is welcome. -c -- Chris Metzler [EMAIL PROTECTED] (remove "snip-me." to email) "As a child I understood how to give; I have forgotten this grace since I have become civilized." - Chief Luther Standing Bear
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