How to handle runway with large diff in elevation.

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jmurtari
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How to handle runway with large diff in elevation.

Post by jmurtari » Thu Jun 11, 2020 9:44 pm

Folks,

Working on a scenery for Harris Hill Soaring, Elmira, NY. See the attached runway image. When taking off to the North (up in the image), the runway crests a meter higher, then drop two meters to the end. The glider is normally airborne well before the end.

Had a problem putting in a flat runway of the entire length, difficult to match surrounding terrain.

Right now we have a short flat runway, up to the '------' on the image, but visually, it really doesn't match what you see from the air. You can see the attached Runway Landscape.

I thought I had seen an earlier posting about runways with different elevations at the ends -- is the possible, how?

The only idea we had was to create a flat landscape object, similar color to the runway, and have it differ in 'z' on its ends -- and attach it to the end of the existing actual runway object.... Sounds very messy!

Any advice is welcome.
Best regards!
John
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dgtfer
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Re: How to handle runway with large diff in elevation.

Post by dgtfer » Fri Jun 12, 2020 1:00 pm

It is possible to have non-flat runways, but till their effective take off your tow-planes will stay on the altitude of the place they start from, so they will be under or above ground. It is also not possible to avoid dents and bumps in the runway, so taking off might be a bit tricky with big gliders...
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Xavier
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Re: How to handle runway with large diff in elevation.

Post by Xavier » Fri Jun 12, 2020 3:35 pm

Hum Jmurati,

IMHO with only 3 meters beteween lowest and highest altitude, you can flatten your airport area (Grass, and Aphalt) and made a smooth ajustement with the Edge slope tool of Landscape editor. Your solution wil be very difficult to insert in your landscapes and as said Dgtfer the bumpyness of the runway make the takeoff tricky. If you want to keep the central bump, you can also use Muck to change the texture of your flat runway part in order to get the same aspect with the runway edges. Also don't forget that the length of the runway in Landscape Editor have not to match the runway length in the c3d G file.
*****- Xavier - (XDL * F-DELX) -*****

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jmurtari
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Re: How to handle runway with large diff in elevation.

Post by jmurtari » Fri Jun 12, 2020 4:41 pm

Yes, just compromising on the elevation may be the best approach.
Thanks for some good advice!
John

JeffSmith
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Re: How to handle runway with large diff in elevation.

Post by JeffSmith » Sat Jun 13, 2020 11:15 am

The way I build the airports now, is to make the inner flattening circle the same diameter as the runway width. I use minimum dimensions for the landing strip to keep the tow plane as close to the center lines as possible. Use the height setting which is reported in the task screen by right clicking on the airport and checking the properties. It's important to move the circle up and down the runway a few times to make sure it is completely flat whilst set on 1. Then set it to 3 or more, keeping the circle outside the runway lines, move it up and down the outside to ensure that the tow plane takeoff and taxi areas are perfectly flat. If in doubt flatten the whole airport area, as a flat landing strip height matching the height file data is the main requirement. You seem to have a nice clear landing area. I've had to modify the landscape on some airfields which are closely surrounded by hills. I feel it is more important to have ideal approaches and takeoffs for pilots, than a 100% accurate landscape as this is a 'flight' simulator program.

bluefang
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Re: How to handle runway with large diff in elevation.

Post by bluefang » Wed Jun 17, 2020 6:59 am

I built a landscape with a prominent sloped runway. It is not perfect, but it is flyable. Landscape is RDU-USA and the airport is Crooked Creek.

I decided to keep the runway sloped instead of flattening it, as this airport is the main hub for all student instruction in the local area, and the sloped runway is one of the prominent features in training students.

At one point I tried a third party topographic editing tool called "Daylan Leveller" - but I had trouble figuring out a decent way to exchange data between the two programs. I eventually ended up just using the raw imported srtm data and trying different methods using the Landscape Editor flatten tool.

Basically what I did was save off the area's default height map so I could always revert back to it - and then make small adjustments / smoothing swipes of the leveling brush in Landscape Editor. Sometimes this produced a totally unflyable bumpy result and sometimes it seemed to smooth things out and approach the real life slope of the runway.

Basically, it is a painful iterative process with lots of undos when things go wrong. The airport is somewhat flyable now, but no where near a nice spline like curve as it is in real life.

I would love to see some basic improvements to the leveling brush in Landscape Editor. Ultimately, it would be awesome to be able to set a start and end elevation, and then draw a line with a specified width where an elevation "curve" of a certain type over that area is applied. That is how the Daylan Leveller works. Heck, even a simple linear curve feature would be better than what we have now - but ultimately, being able to specify splines would be most effective.
Last edited by bluefang on Fri Jul 10, 2020 5:02 am, edited 1 time in total.
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jmurtari
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Re: How to handle runway with large diff in elevation.

Post by jmurtari » Thu Jun 18, 2020 10:14 pm

OK, useful information! I'm assuming you didn't try to put in a 'real' grass texture runway, just flattened the terrain as much as possible.

Yes, it would be nice to set a few points at different elevations and ask for a smooth transition....

bluefang
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Re: How to handle runway with large diff in elevation.

Post by bluefang » Wed Jun 24, 2020 2:49 pm

jmurtari wrote:
Thu Jun 18, 2020 10:14 pm
OK, useful information! I'm assuming you didn't try to put in a 'real' grass texture runway, just flattened the terrain as much as possible.

Yes, it would be nice to set a few points at different elevations and ask for a smooth transition....
My runway has a section with grass texture applied - but not on the entire runway.

It ended up that the flattening I did was to draw perpendicular lines (perpendicular to the direction of the runway) - of equal elevation. Basically what I tried to do was, say start at one end of the runway and determine what the avg elevation was and flatten a perpendicular line across the runway at that elevation. I repeated this all the way down to the other end of the runway - adjusting the elevation as needed to create the appropriate slope.

It is not perfect - and there are still triangulation bumps - but it ended up somehow being better than leaving the default srtm elevation data in place.
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