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FSX: airport elevation change

Discussion in 'BGLComp XML, AFCAD, SceneGenX' started by scott967, 4/6/07.

  1. scott967

    scott967

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    I was doing a little scenery project to redo the Wabash River in SW Indiana, US. That went OK, but there is a little grass strip II33 right along the river. The problem is that the default airport is set at 194m, whereas the terrain appears to be about 124m. I looked at it in FS9 with FSG mesh, and the same problem is in there. In FSX, it appears that MS has jiggered the default mesh to create a hill for II33 to sit on, but it's so close to the river that causes a steep cliff (I don't have FSX improved mesh but I used GE and the USGS data to get "ground truth".

    Anyway I see the same kind of elevation problem as with FS9: I create an xml file from the default and change the airport, runway, and start elevations to 124m (lower than default), deleted the runway and starts compiled and placed in addon scenery. When I start at II33, aircraft is placed and I have a floating runway at the default 194m. So I created an airport element xml @ 124m compiled and placed it in the default scenery\0302\scenery and that fixed it. So I guess we have the same problem as FS9 with elevation changes not taking in all cases unless an "afcad"stub is in the default folders?

    scott s.
    .
  2. Mace

    Mace

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    Scott:

    Airnav.com says it's 189m (estimated) elevation. That cannot be accurate (unless it's on an indian burial mound), and you can take that from someone who lives fairly close to there.

    But that doesn't surprise me. A tiny field like this, all data is relied upon by the owner, so that's bound to be inaccurate. Plus I am mildly amused by the note on Airnav that says, "OWNER DESIRES AIRPORT NOT TO BE CHARTED". :)

    GoogleEarth shows the location to be 128m elevation. I am from the area and know that it cannot be 189m (600+ feet). That is too high, all of our river basins are down in the 400's range, maybe 500 feet ASL over there. So that's how I know 189m is improbable at best.

    If it were me, I would first EXCLUDE the default flatten there using FSX_KML or similar tool. Then I would make an <Airport> xml file with a <DeleteAirport> xml construct in it. I would DeleteAllRunways="TRUE".

    That kills off the default flatten and the default runway and also the default "mesh adjustment" that goes with a runway. Now I would be free to make the strip at it's proper 128m elevation.

    At such a small strip, if you don't plan to have any AI there, you could even make it a sloping runway (no flatten). There probably is very little slope there, in real life so it would work well. That strip is about 120 miles east of me, closest I have been is Fairfield IL, about 30 miles west of there.

    Put in two starts (one for each end) and you're good to go.

    I'd bet 128m will look much much better with the surrounding mesh, too. After you exclude the default flatten, I bet you'll see that the mesh there is close to 128m.
  3. jvile

    jvile

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    Scott

    Place your new airport header and elevation associated with it in the World\Scenery folder.

    This will preload FS with a basic Header with the new altitude data loaded before the default airport. Now use the AFCAD at the Addon scenery\scenery to lay out the redesigned airport.

    Make sure the AFCAD Reference, Runways, Start locations and any NAVaids have the same new elevation that is in your dummy Header.

    If you are placing the dummy in the Folder/Dir it will be name sensitive and may cause elevations not to load correctly from time to time.

    Mace's idea sounds good but it does not consider the Airborne traffic that loads in the visual AI Zone seeking a airport runway elevation vs the startup User/AI Planes that load on the ground for proper wheel contact.

    You can make a airport look correct but the many elevations that FS9/FSX works with can cause Planes (airborne vs aircraft that load on startup) not to seek the correct ground elevation.

    Airborne Traffic seeks AFCAD runway elevation
    Aircraft that spawn at a airport on startup seek Airport Header elevation
  4. Mace

    Mace

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    Please elaborate.

    This is a small strip with zero AI.

    I'm not sure what you are speaking of, but want to know.
  5. scott967

    scott967

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    I have not had consistent success using world/scenery in FS9. In this case, putting the "stub" file in world/scenery does work. But I guess my real question is does FSX work the same way as FS9 when changing the elevation of a default airport? There's no AI at this airport, so I haven't looked into the problem of sinking/floating AI which happened in FS9, just the start position and visual runway for the user aircraft, both starting at the airport and flying into it.

    scott s.
    .
  6. jvile

    jvile

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    Scott

    I have not had a chance to test the elevation issue we had in FS9 when the ARP elevation has to be preloaded do to a scenery elevation change.

    We talked about this with Thomas from ACES prior to the release of FSX. His response was somewhat vague if in fact FSX was going to behave differently then FS9.

    His exact quote was

    It appears you are the first to work on an exsiting airport that will show if FSX/SP1 does make a difference or if we have to apply the FS9 rules to airport elevation changes.

    Save a flight with your plane on the grass of the airport and then load that flight as the default. If the Airport Header ARP elevation is preloading correctly the wheels will contact the hard floor of the ground and match the elevation you set.

    Once you know the hard floor is matching the ground scenery then adjust all AFCAD elevations to the stub dummy ARP elevation. When you fly to the airport from another AI Visual sector the Runway altitude should be the exact same hard floor as the dummy ARP.

    But, FSX may be treating all this differently and 3rd party scenery that does not adhere to the ARP elevation in the APX file will once again have problems short of using Jabbgl or a stub dummy ARP. Thomas clearly points out that Jabbgl is out of the question even though it hex'ed the elevations rather then decompile.

    I still see uploads for FS9 where the designers are passing out reworked FL bgls and AP Jabbgl's.

    It will get real interesting when FSX planner and ADE are released because they unlock all the elevations for each airport and then in turn add the default pulling up of the terrain that FSX does on it own.
    Last edited: 5/6/07
  7. Mace

    Mace

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    I do know, that in FSX, you do not have to "remove existing code" to remove default flattens.

    Default flattens can now be excluded just like any other scenery element. Only they must be excluded using a polygon with the correct (exclusionary) guid.
  8. jvile

    jvile

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    Very true Mace and some of us are using the GUID's to give us the desired flattens. I was glad to see that FSX reworked the FL type bgl's that were in FS9 and went with the current terrain design technique.

    However, that is a visual of what looks right and does not mean a airport is functional. Even if there are no AI's a User Plane may want to land at the airport but may not find the hard floor to be in the right place.

    More study like Scott is doing needs to be done to see if FSX fixed a better way of setting the hard floor of a airport which is controlled by the APX file and not the visuals of terrain.
  9. Mace

    Mace

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    I believe AI aim for the ARP elevation, so I would think as long as the ARP elev and the flatten elevation match, things should work well.

    I would think that if you have a DeleteAirport in your replacement file, that you could then define a new ARP elevation to match your new flatten elevation.

    I would HOPE that the stock file elevation would not matter at all at that point.

    If the stock ARP still matters, then we have a big problem imo.

    A few months back I was experimenting with sloped runways and came upon many of the issues touched on in this thread.
  10. jvile

    jvile

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    Not in FS9 but maybe in FSX.

    ARP elevation in FS9 is the hard floor altitude for Planes that load on startup.

    Runway elevation in FS9 is the hard floor altitude for airborne planes landing that enter the AI Visual zone.

    This also applies to the User Plane not just AI.

    In the AP9/APX those elevations are always the same. Once a utility like AFCAD unlocks the different elevations then users change things which cause floating or sunken wheels.

    3rd party scenery designers sometimes change their scenery elevation (a little higher or lower) which is fluid in design and then think AFCAD can correct all the elevation issues. Nothing outside of a preload for the airport header will change the airport ARP elevation that planes use for wheel contact on startup.

    With more testing we will get to the bottom of what Scott is seeing and hopefully like you say FSX is treating the ARP startup load and runway elevations differently.
    Last edited: 6/6/07
  11. HolgerSandmann

    HolgerSandmann Resource contributor

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    Hi guys,

    we've been using the same appraoch as in FS9 - a copy of the adjusted header information into \Scenery\World\scenery - to ensure that elevation corrections to airport data work as intended.

    We tried using the regional numbered folders (e.g., \Scenery\0101\scenery) instead but even ensuring alphanumerical priority yielded inconsistent results: for three out of 30+ Beta testers a few of our corrected airports still used the default elevation. Moving the header files back into \Scenery\World\scenery got rid of the issue.

    Cheers, Holger
  12. jvile

    jvile

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    Hi Holger

    I did not think to ask you if you saw any difference with FSX. I knew you and Jon P where working on the new FSX project.

    I really can't see how FSX could be any different then FS9 in reading the elevations because not much was done on the AI/User Plane coding which is where Airport ARP/Runway elevation hard floor is used.

    You remember way back when we discussed naming conventions when files sit in the same folder. It appears that FS sometimes has a hard time reading bgl's in order based on first letter naming. It always worked much better if a preload was before the first scenery Load (Africa).

    All those post you Reggie and I had over on PAI are gone so no way to link what our research showed. Back to explaining things all over again when needed.

    I am updating all my exoctic curved approach code and airport layout for FSX LOWI. You got anything in the works for that valley?

    Doing Kai Tak for FSX but don't need a mesh this time around. FSX finally put the hill in for the checkerboard put now there is no airport in real world.
    Last edited: 7/6/07
  13. scott967

    scott967

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    Results of testing so far:

    Airport II33
    airport has 1 grass runway, no taxiway, no apron, no AI

    Installed revised mesh file in addon scnenery
    Compiled an exclude all airport boundary polygon and installed in addon scenery

    Started FSX. Airport boundary and flatten is removed. "ground" level is 397 ft.
    Default airport runway with "runway flatten" at default elevation 626 ft.


    Installed airport boundary polygon with flatten, maskclassmap, exclude autogen in addon scenery

    started FSX. airport boundary and flatten in place with correct flatten elevation 413 ft. Runway is "floating in the air". Runway is landable. Taxi on/off runway drops or raises aircraft instantly to flatten elevation or floating runway elevation.

    Created AFX file:

    <Airport
    country="United States"
    state="Indiana"
    city="Charleston"
    name="Eickholtz"
    lat="38.460880368948"
    lon="-87.6550255715847"
    alt="124.054M"
    trafficScalar="0.7"
    airportTestRadius="5000.0M"
    ident="II33"
    >
    <Tower
    lat="38.4600022807717"
    lon="-87.6548279821873"
    alt="16.459M">
    </Tower>
    <Services>
    </Services>
    <DeleteAirport
    deleteAllApproaches="FALSE"
    deleteAllApronLights="FALSE"
    deleteAllAprons="FALSE"
    deleteAllFrequencies="FALSE"
    deleteAllHelipads="FALSE"
    deleteAllRunways="TRUE"
    deleteAllStarts="TRUE"
    deleteAllTaxiways="FALSE"
    deleteAllBlastFences="FALSE"
    deleteAllBoundaryFences="FALSE"
    deleteAllControlTowers="FALSE"
    deleteAllJetways="FALSE"/>
    <Runway
    lat="38.460880368948"
    lon="-87.6550255715847"
    alt="124.054M"
    surface="GRASS"
    heading="80"
    length="914.4M"
    width="15.24M"
    number="08"
    designator="NONE"
    patternAltitude="304.8M"
    primaryTakeoff="YES"
    primaryLanding="YES"
    primaryPattern="LEFT"
    secondaryTakeoff="YES"
    secondaryLanding="YES"
    secondaryPattern="RIGHT">
    <Markings
    alternateThreshold="FALSE"
    alternateTouchdown="FALSE"
    alternateFixedDistance="FALSE"
    alternatePrecision="FALSE"
    leadingZeroIdent="FALSE"
    noThresholdEndArrows="FALSE"
    edges="FALSE"
    threshold="FALSE"
    fixedDistance="FALSE"
    touchdown="FALSE"
    dashes="FALSE"
    ident="FALSE"
    precision="FALSE"
    edgePavement="FALSE"
    singleEnd="FALSE"
    primaryClosed="FALSE"
    secondaryClosed="FALSE"
    primaryStol="FALSE"
    secondaryStol="FALSE"/>
    <Lights
    center="NONE"
    edge="NONE"
    centerRed="FALSE"/>
    </Runway>
    <Start
    type="RUNWAY"
    lat="38.4601893648505"
    lon="-87.6600216329098"
    alt="124.054M"
    heading="80"
    number="08"
    designator="NONE"/>
    <Start
    type="RUNWAY"
    lat="38.4615710377693"
    lon="-87.6500295102596"
    alt="124.054M"
    heading="260"
    number="26"
    designator="NONE"/>
    </Airport>


    Installed in addon scenery

    Started FSX. runway is still floating, no observable difference from not having the AFX file installed.

    Tried playing around with variation of the Delete Airport element: no effect
    Tried adding a second runway: new runway is floating. I tried to fly under the runway and crashed :)

    scott s.
    .
    Last edited: 22/8/08
  14. HolgerSandmann

    HolgerSandmann Resource contributor

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    Hi there,

    Scott, you need to install your AFX file in a location that has a higher priority in the sim, i.e., is read before the default files in the regional folder. Hence our suggestion to place the edited header files in Scenery\World\scenery.

    Jim, great to hear you're updating the curved approaches to FSX. I've started porting my freeware projects to FSX but it's a slow process. Haven't even looked at LOWI yet though I believe that the default landscape data in FSX are much better than in FS9, including terrain, roads, and water bodies.

    Cheers, Holger
    Last edited: 7/6/07
  15. pierrot1951

    pierrot1951

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    Hello!

    After many "try and fail", I have now a working method to move elevation / position of a simple airport (no approach, ...); it has rather long steps at the moment, but if well organized, it works.
    Will be easier with next to come ADE or FSX_Planner versions.
    Tested with a dozen of airports in Madagascar to suit improved mesh and GE position. AI traffic automatically used new data.

    I link to an abstract of method:
    http://www.fsdeveloper.com/forum/showthread.php?p=33413#post33413
    Modified airport will now display at correct position, elevation in maps...

    Pierrot - FMEP
  16. Mace

    Mace

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    I will have to keep this in mind if I decide to change an airport's elevation.

    I don't like putting non-stock files in stock directories AT ALL.

    I wonder why Microsoft made this design choice?
  17. scott967

    scott967

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    I've wondered about this too, because it seems like if you create new airport, you can put that in an addon scenery folder, and it will work correctly, it's only if you change a default ARP that it won't pick it up.

    scott s.
    .
  18. Mace

    Mace

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    Let me see if I am understanding this correctly:

    _IF_ I have an airport that in default FSX is at 25.6 meters elevation, and I wish to change that to 18.7m elevation, it WILL NOT WORK, if I simply change the flatten, change the <Airport> elevation in my <Airport> section of my xml, and change the <Runway>s also. So we are saying, that this is NOT enough?

    Is my understanding correct?

    Instead, I will have to do file placement? Dummy <Airport> header in a stocker directory?
  19. meshman

    meshman

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    withdrawn.
    Last edited: 29/6/09
  20. scott967

    scott967

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    I have completed another round of testing. In this round I started where I left off -- excluded the default flatten (boundary) installed my own boundary at LOWER elevation (413 vice 627) and installed an FAX file deleting the default runway and starts, and establishing the new ARP elevation of 413 alogn with new runway and starts at the same elevation.

    Now I created the "stub" airport with identical airport attributes except for LOWER elevation:

    <Airport
    country="United States"
    state="Indiana"
    city="Charleston"
    name="Eickholtz"
    lat="38.460880368948"
    lon="-87.6550255715847"
    alt="124.054M"
    trafficScalar="0.7"
    airportTestRadius="5000.0M"
    ident="II33"
    >
    <Services>
    </Services>
    </Airport>

    I tested with install this in several default scenery areas, including BASE, World, 0301, 0302, 0303, and Global. What I found is that when the stub file was installed in any lower (or = i.e. 0302) priority scenery area, the visual runway was as "ground" level and the user aircraft would load at both starts and land at the proper elevation. When installed in any higher level sceenry area there was no apparent effect as compared to not using it.

    Again, the following may (or may not) be a factor:
    no taxiways, aprons, parking or assigned AI at either default or mod airport
    mod airport at same lat/long ARP
    airport elevation lowered.

    scott s.
    .

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