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P3D v3 Platforms usage in ground flat objects.. ?

Hi I am almost finished my taxiways/runways so i decided to play with platforms and have a question...

Reason I used platforms was because when i place the object tires of aircraft sink into the ground all though ever so slightly they do.

I place the object at 0.02 m or 2 centimeters AGL that nicely gets rid of any and all flickering,
I use "convert and place object" wizard for that, NOT "ground poly".

.. so after adding the platforms which I added at 0.02 as well (testing 0.00 had no effect on tire sink) and seems 0.02 worked very well, however... I lost the effect of water spray from under tires. When I taxi onto an area that does not have platform the effect returns.

I did read a bit about platforms and most seem to use it for roofs, bridges etc.. which makes sense, I intended to make my runways/taxiways object a "hard surface", well that was the idea.. I have no clue how to make them hard surface any other way. :( I use SU to create them and MCX to import all my objects.

few other things using Auto Platform I don't think it did anything so all my platforms are manual, also did have a problem that it double few of the platform after re-importing the MDL, since i don't have all that many it wasn't a big deal i just removed the doubles.

any help greatly appreciated




Staff member
FSDevConf team
Resource contributor

Won't you get problems with the curve of the earth if you use the ground polygons like this? At the end of your runway it might float.

I think the loss of the spray is probably normal for platforms. They were never intended to be used for making entire airports hard.


Resource contributor
The flickering you refer to is likely a consequence of Earth curvature or irregular ground, you probably want to experiment with flattens as opposed to hard platforms. Hard platforms are intended to make model objects represent the ground, allowing autogen cars to traverse bridges and helicopters to land on oil rigs. They are not intended to compensate for discrepancies between ground polygons and actual ground and used as such can only work haphazardly at best, lost spray effect being indicative of that.

Interesting idea, however, to make those poor access runways that have to be built partly on platforms; but it would not work if a road passed under.
I agree that one should abide by the ACES' reported recommendation to segment Ground Polygons (aka "G-Polys") into pieces no larger than ex: "100 Meters" per span to avoid mis-alignment of textured surfaces with the underlying terrain flattens (either 'flat' or 'sloped').

IMHO, one might wonder whether what ACES actually meant was that G-Polys should be segmented to no larger than 76.4 Meters or 152.9 Meters for 'pivot' edges of LOD-9 or LOD-8 terrain grid Area Points, and all ground tile "edge end-points" are to be aligned with the vertices of the FS quad mesh terrain grid ...to avoid mis-alignment with the FS 3D world "curved Earth" model. ;)

If one needed to create an elevated platform which could support AI or user-pilotable aircraft and apply a custom high-resolution texture, this can be done as either a 3D model with platform or as a Ground Polygon.

A fascinating example of how this actually works is seen in this fun add-on from the folks at RTMM that has a water ramp leading to a surface (well above ground !) using hardened platforms onto which one can pilot the user aircraft:

Thumb Harbour - PF31 (Added 07.14.2011)(Updated 02.11.2012) by Xavier Carre' at Return To Misty Moorings (aka "RTMM")

http://www.return.mistymoorings.com/scenery/#Thumb Harbour


NOTE: This scenery will require another separate download to get the seaplane ramp with elevated and hardened platform library object:

CeyX_Sceneries_Libraries by Xavier Carre'

Current Link as of 12/13/2012:


FYI: Should the above "CeyX_Sceneries_Libraries" link to the required 'latest libraries by Xavier Carre' ever change or go dead, it is found in:

Barnstormers: Part One - Tweedsmuir-Nechako By Xavier Carré and Jacques Alluchon

...under: "NOTAM: The Latest CeyX Object Library Must be installed to make this work (Click Here) "

http://www.return.mistymoorings.com/scenery/#Barnstormers: Part One

http://www.return.mistymoorings.com/scenery/zipfiles/barnstormers/Barnstormers 1.0.zip

BTW: One can pilot an aircraft beneath the raised platform as well as up onto the raised platform itself ...with both water and platform elevations correctly displayed ! :wizard:

Hint: Turn off user aircraft 'crash detection' to taxi underneath the platform to inspect this scenery and see how the elevations are all working properly.

PS: IIUC, the techniques used in this process should also work for making hardened surfaces over land that allow aircraft to be fully supported while keeping underlying terrain levels at correct elevations. ;)

Hope this helps ! :)

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I taxi to far out most point of the runway and I suppose indeed airplane might be floating ever so slightly, but it is very hard to notice (especially using default p3d camera) say at the center of platform it is perfect with runway while at the end it could appear to float at maybe 5cm or so again very hard to notice, you are much more likely to notice it sink in the ground 5cm vs 2cm then it floating LOL

Either way as I am seeing from your responses the platforms are not meant for that so I am removing them and that is what it looks like without them which in my opinion is quite OK
tire sink.jpg

not too much of an eyesore...

I much prefer to have tire smoke effects and water effect behind engines or tires as oppose to tire being dead on flat on the runway.

I tried with ADE as Rick suggested to create a flatten area as per ADE instructions which is pretty easy and it had no effect that is what it looked like (all platforms at this point were removed from MDL)
flatten alt 0.jpg

the texture below which is sbuilderX scenery would just bleed through the runway object when placed at 0 or 1 cm AGL, and this was the case through out the entire runway pretty evenly so I don't suspect any obvious terrain elevation differences where at some places it would be less or more obvious. only changes with camera viewing angle.
Once I placed it at 2 cm AGL (same as originally just now using flatten from ADE as well) all of the bleeding through/flickering disappears and you are left with nice smooth texture, only that the tire as shown above does appear to be an inch (2.5 cm) into the ground LOL, well I will jut leave it like that for now...

one more thing I'd like to clarify and I am not sure if there is a difference or not...?

My object is indeed flat as is ground poly, but the way I process it though MCX is the same I would something that is NOT, like a building for example.
If I was to extrude a wall at the end (or any other place) of my runway/taxiway object it would appear in the sim unlike when you use the "convert to ground poly" wizard which would to my understanding remove all the vertices above ground level, mine would remain with the wall,
I could for example attach this whole thing to my terminal and and it would be one big object, but i prefer to keep them separate.
The reason I did it like that was because when I first made it a simple ground poly with the wizard, then place the taxi lights on it or any other lights they would not "illuminate" the surface, not even the light rays would be visible over it.
Later I read in other post that is has something to do with the way MCX makes it a ground poly, something about it using FS2002 way to make it and neither rain/reflections etc. will work on it.

when i complied as I would with any other 3D object everything works, rain,bump maps, reflections, light nicely illuminate the parts where they are placed... and so on.

OK I just wanted to clarify that in case it matters.

Well anyhow for now platforms are out at least for this kind of use, again its not that bad I was just looking for perfection LOL