Re: [Flightgear-devel] Re: [Terragear-devel] Flattening Stuff
On Fri, 05 Sep 2003 10:34:05 +0200, Christian Mayer <[EMAIL PROTECTED]> wrote in message <[EMAIL PROTECTED]>: > David Culp schrieb: > > > > On a related note, here are some airports that the FAA considers > > "special", as of 1990, and why: > > > > [...] > > > > EUROPEAN REGION > > > > AIRPORT COMMENTS > > > > Berlin, Germany Political sensitivity > > ofcorridor adherence. > > Thank God that's gone since 1990 (October 3rd to be presice...) ..amen! > > [...] > > > > WESTERN-PACIFIC REGION > > > > AIRPORT COMMENTS > > > > Hong Kong Int'l.Special approach; > > (British Colony, S.E. China)mountainous terrain. > > That'll be the old Hong Kong Airport. Isn't "special approach" quite > an understatement? ..heh, try ENHV. ;-) -- ..med vennlig hilsen = with Kind Regards from Arnt... ;-) ...with a number of polar bear hunters in his ancestry... Scenarios always come in sets of three: best case, worst case, and just in case. ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Re: [Terragear-devel] Flattening Stuff
David Culp schrieb: On a related note, here are some airports that the FAA considers "special", as of 1990, and why: > [...] EUROPEAN REGION AIRPORT COMMENTS Berlin, Germany Political sensitivity of corridor adherence. Thank God that's gone since 1990 (October 3rd to be presice...) [...] WESTERN-PACIFIC REGION AIRPORT COMMENTS Hong Kong Int'l.Special approach; (British Colony, S.E. China)mountainous terrain. That'll be the old Hong Kong Airport. Isn't "special approach" quite an understatement? CU, Christian ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Re: [Terragear-devel] Flattening Stuff
David Megginson writes: > Curtis L. Olson writes: > > > For what it's worth, when I was looking into this, I found some > > examples of runways with their ends literally at least 100' different > > in elevation. Most aren't nearly that far off, but there are a > > few. > > For a 10,000 ft runway, that would require less than a 1% continuous > grade, so it's not all that surprising. > > It will be a very good thing when we can take threshold elevations > from FAA and DAFIF data. The SRTM/DEM data, however, is just too > coarse -- that's why I'm suggesting flattening for now. David, one thing I could point out is that there is code in the apt_surface.cxx to limit the amount of total elevation change over the surface of the airport. If nothing else you play around with the clamping bounds and see if you can find a value that works better for you. Regards, Curt. -- Curtis Olson HumanFIRST Program FlightGear Project Twin Citiescurt 'at' me.umn.edu curt 'at' flightgear.org Minnesota http://www.menet.umn.edu/~curt http://www.flightgear.org ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
RE: [Flightgear-devel] Re: [Terragear-devel] Flattening Stuff
Curtis L. Olson writes: > Norman Vine writes: > > David Megginson writes: > > > > > > Norman Vine writes: > > > > > > > Have you tried preinserting some of the the higher res srtm1 data > > > > to terra innide of and on the edges of the airport polygons ? > > > > > > > > This shoud be quite accurate. > > > > > > Maybe *too* accurate -- at the resolution, a 747 parked on the field > > > will start to show up in the elevations, not to mention large hangars > > > and the terminal buildings. > > > > Whatever, the point is try preinserting some points for the airports > > I think you will be pleasantly surprised :-) > > I would worry that preinserting points would yield spikes whenever the > FAA surveyed elevation differs from the SRTM data ... in otherwords > imagine the SRTM surface with spikes whereever we place our > "pre-inserted" points. Agreed this is why I suggested using the higher res SRTM data in the vicinity of the airports Cheers Norman ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
RE: [Flightgear-devel] Re: [Terragear-devel] Flattening Stuff
Norman Vine writes: > David Megginson writes: > > > > Norman Vine writes: > > > > > Have you tried preinserting some of the the higher res srtm1 data > > > to terra innide of and on the edges of the airport polygons ? > > > > > > This shoud be quite accurate. > > > > Maybe *too* accurate -- at the resolution, a 747 parked on the field > > will start to show up in the elevations, not to mention large hangars > > and the terminal buildings. > > Whatever, the point is try preinserting some points for the airports > I think you will be pleasantly surprised :-) I would worry that preinserting points would yield spikes whenever the FAA surveyed elevation differs from the SRTM data ... in otherwords imagine the SRTM surface with spikes whereever we place our "pre-inserted" points. I think we would have to use the FAA surveyed data as "error" correction terms and then interpolate these error correction terms over the surface. I plan to try that sometime when I get some time. In otherwords ... start with the list of FAA surveyed points that you know for certain. For each of these also calculate the corresponding SRTM elevation. Now subtract the two to get the difference (or error term.) Do this for all the FAA surveyed points. Now build a list of points of the form: (lat, lon, error) and triangulate that. Now for each point of the airport you can compute a true elevation by taking SRTM height + the error term interpolated from our error surface. Not sure if that would introduce more problems than it solves but it gives me warm fuzzy feelings at the moment. :-) Curt. -- Curtis Olson HumanFIRST Program FlightGear Project Twin Citiescurt 'at' me.umn.edu curt 'at' flightgear.org Minnesota http://www.menet.umn.edu/~curt http://www.flightgear.org ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
RE: [Flightgear-devel] Re: [Terragear-devel] Flattening Stuff
David Megginson writes: > > Norman Vine writes: > > > Have you tried preinserting some of the the higher res srtm1 data > > to terra innide of and on the edges of the airport polygons ? > > > > This shoud be quite accurate. > > Maybe *too* accurate -- at the resolution, a 747 parked on the field > will start to show up in the elevations, not to mention large hangars > and the terminal buildings. Whatever, the point is try preinserting some points for the airports I think you will be pleasantly surprised :-) Cheers Norman ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
RE: [Flightgear-devel] Re: [Terragear-devel] Flattening Stuff
Norman Vine writes: > Have you tried preinserting some of the the higher res srtm1 data > to terra innide of and on the edges of the airport polygons ? > > This shoud be quite accurate. Maybe *too* accurate -- at the resolution, a 747 parked on the field will start to show up in the elevations, not to mention large hangars and the terminal buildings. All the best, David ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
RE: [Flightgear-devel] Re: [Terragear-devel] Flattening Stuff
David Megginson writes: > > Curtis L. Olson writes: > > > For what it's worth, when I was looking into this, I found some > > examples of runways with their ends literally at least 100' different > > in elevation. Most aren't nearly that far off, but there are a > > few. > > For a 10,000 ft runway, that would require less than a 1% continuous > grade, so it's not all that surprising. > > It will be a very good thing when we can take threshold elevations > from FAA and DAFIF data. The SRTM/DEM data, however, is just too > coarse -- that's why I'm suggesting flattening for now. Have you tried preinserting some of the the higher res srtm1 data to terra innide of and on the edges of the airport polygons ? This shoud be quite accurate. Cheers Norman ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
re: [Flightgear-devel] Re: [Terragear-devel] Flattening Stuff
Martin Spott writes: > > Further to Curt's last post about flattening rivers, how would > > everyone feel about flattening airports? > > When you look at large airports, say with runways over 3 km, you'll find > quite a few where the runways follow the terrain at least over a difference > in the elevation of several meters. Absolutely -- at my home airport, for example, runway 14/32 (10,000 ft) has a significant hump in the middle. We have one old 727 that flies up north to Baffin Island every day, loaded so that it can barely climb. You can tell it's starting its takeoff roll because you see a cloud of smoke over the horizon -- a few moments later, the plane itself comes into view, struggling its way off the runway with the nose hanging high in the air. With all the drag, we give that one at least three minutes (instead of the normal two) when it takes off across our runway. The problem is that we're not generally getting that right now anyway -- we're just getting incorrect elevations. All the best, David ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Re: [Terragear-devel] Flattening Stuff
Curtis L. Olson writes: > For what it's worth, when I was looking into this, I found some > examples of runways with their ends literally at least 100' different > in elevation. Most aren't nearly that far off, but there are a > few. For a 10,000 ft runway, that would require less than a 1% continuous grade, so it's not all that surprising. It will be a very good thing when we can take threshold elevations from FAA and DAFIF data. The SRTM/DEM data, however, is just too coarse -- that's why I'm suggesting flattening for now. All the best, David ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Re: [Terragear-devel] Flattening Stuff
Some good examples of un-flat runways: KATL ( especially 8R, concave ) San Jose, Costa Rica ( steep slope, strong visual illusion ) Guatemala City, Guatemala ( very concave runway ) On a related note, here are some airports that the FAA considers "special", as of 1990, and why: APPENDIX 1. SPECIAL AIRPORTS ALASKAN REGION AIRPORT COMMENTS Dutch Harbor, AKMountainous terrain. Juneau, AK Mountainous terrain. Ketchikan, AK Mountainous terrain on both sides of final approach. Kodiak, AK Airport is surrounded by mountainous terrain. Any go-around beyond ILS or GCA MAP will not provide obstruction clearance. Petersburg, AK Mountainous terrain in immediate vicinity of airport, all quandrants. Sandpoint, AK Mountainous terrain. Seward, AK Mountainous terrain in the immediate vicinity of airport. Sitka, AK Obstruction in missed approach, all quadrants. Valdez, AK Mountainous terrain in immediate vicinity of airport. Wrangell, AKMountainous terrain in immediate vicinity of airport all quadrants. U.S. MILITARY AIRPORTS AIRPORT COMMENTS Adak, AKSpecial conditions due to precipitous terrain. Cape Lisburne AFS, AK Mountainous terrain in approach zones; nonstandard instrument approach. Cape Newenham AFS, AK Runway located on mountain slope with high gradient factor; nonstandard instrument approach. Cape Romanzof, AK Runway located on side of mountain; mountainous terrain both sides and north end of runway. Indian Mountain AFS, AK Mountainous terrain. Sparrevohn AFS, AK Mountainous terrain. Tatlina AFS, AK Unique approach; mountainous terrain. + Tin City AFS, AKMountainous terrain. EASTERN REGION AIRPORT COMMENTS Beckley, WV Mountainous terrain. Bluefield, WV Mountainous terrain. Charleston (Kanawha), WVMountainous terrain. + Cumberland, MD Mountainous terrain. Elmira (Chemung), NYMountainous terrain. + Elkins, WV Mountainous terrain. Harrisburg Int'l., PA Mountainous terrain. Hot Springs, VA Mountainous terrain. Roanoke, VA Mountainous terrain. Huntington, WV Mountainous terrain. Washington, DC (National) Special arrival/departure procedures. Wilkes-Barre, PAMountainous terrain. Binghamton, NY Mountainous terrain. + Saranac Lake, NYMountainous terrain. Shenandoah Valley, VA Mountainous terrain. (Stanton-Waynesboro-Harrisonburg) EUROPEAN REGION AIRPORT COMMENTS Berlin, Germany Political sensitivity of corridor adherence. Stuttgart, Germany Complex ATC procedures; limited approach
Re: [Flightgear-devel] Re: [Terragear-devel] Flattening Stuff
Don't recall the specific change in height of the two runway ends, but KMRY has quite a downslope change toward the West as one real world example. jj > For what it's worth, when I was looking into this, I found some > examples of runways with their ends literally at least 100' different > in elevation. Most aren't nearly that far off, but there are a few. ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
Re: [Flightgear-devel] Re: [Terragear-devel] Flattening Stuff
Martin Spott writes: > David Megginson <[EMAIL PROTECTED]> wrote: > > Further to Curt's last post about flattening rivers, how would > > everyone feel about flattening airports? > > When you look at large airports, say with runways over 3 km, you'll find > quite a few where the runways follow the terrain at least over a difference > in the elevation of several meters. > Still that's not hundreds of feet :-) For what it's worth, when I was looking into this, I found some examples of runways with their ends literally at least 100' different in elevation. Most aren't nearly that far off, but there are a few. Curt. -- Curtis Olson HumanFIRST Program FlightGear Project Twin Citiescurt 'at' me.umn.edu curt 'at' flightgear.org Minnesota http://www.menet.umn.edu/~curt http://www.flightgear.org ___ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
