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Taxiway Ground Poly questions

N7277U

N7277U

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us-illinois
I'm trying to build an airport in FS2004 using GMAX and FS2002 gamepack techniques for my runways, taxiways and ramps. In reading through posts on this forum I've found information on laying out these features, but have a few questions.

Making the layout from one reference point, using lines/splines for outlining pavement features appears to be a good method. This link from an older post to a rendering from Nick(Kack911)shows a sample layout in this method:

http://www.fsdeveloper.com/forum/attachment.php?attachmentid=1278&d=1160951079

Questions:

1. To create an outline against a background aerial photo in GMAX, does the image need to be projected in lat/lon WGS84, or is this needed only for use in LOD tiles created by the FS resample tool?

2. At taxiway intersections, where there are curved fillest in the pavement, what is the best way to apply textures to these non-uniform shapes. Can tiled concrete or asphalt textures still be used, or does tiling only work for rectangular shapes?

3. I understand that pavement markings (lines) can be placed using the loft technique, so curved segments shouldn't be a problem. However, if you have a higher poly layer for cracks and dirt, how would that be done for a curved path (for example where a taxiway path/line curves to join another taxiway or runway)?

Thanks in advance for any assistance!

Mark
 
Hi Mark,

I'm certainly no expert yet, so I'm sure Arno or one of the others will chime in with better answers.

1) If you're referring to simply using an aerial photo as a background for designing within Max/Gmax, then you don't need to worry about georeferencing anything. You just have to know the exact dimensions of the photo you're working with.

A cheap and easy source (if up-to-date) is Google Earth. I setup the zoom and orientation to cover the area I need, go to full screen, and use the measure tool to calculate the height and width of the screen area. Then I save the image (ctl+alt+s).

Create a plane or an editable poly of the same dimensions and apply the image as the diffuse texture. I lower the plane .25' so all of my splines draw on top of the image.

If you knew all of that already, then please accept my apologies...

If you're trying to export the imagery itself into FS, then I have no idea how that process works.

2) Tiled textures "work" on irregularly shaped polys, but they don't follow the curves.

3) If I understand what you're asking correctly, then you should be able to create a wider curved poly using the same technique used to create the taxi lines. Proper use of a texture containing an alpha layer would make such a poly semi-transparent and create the illusion of tire scrubbing.

I'm not terribly familiar with Gmax, but in Max 8, the "Sweep" modifier works WAY better than lofting the taxi lines. In Max 8, I have to loft each line individually, and on dome of the large airports I've made, that might mean 500-600 individual lofts.

With the Sweep modifier, you can select all of your lines at once, and sweep them with a single template shape (a simple spline the desired width of the taxi line). If Gmax has the Sweep modifier, I recommend you use that instead.

Hope I'm not too far of the mark, ;)

Regards,

Nick
 
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Thanks, Nick!

I'm glad to learn that I don't have to reproject my background image. That will make things simpler. Your suggestion of placing the image on a poly, rather than setting it as a background in GMAX sounds like an excellent way to do this.

I'm not familiar with the "sweep" modifier, at least I haven't come across it within GMAX or elsewhere in these forums. I'll take another look, though, as it sounds like a great way to do all of those lines.

One additional question for you. When you draw individual polys for different pavement areas, what is the best way of joining these, while still retaining the ability to select and texture them as separate polys? Do you weld verticies? Use the attach tool?

Thanks again!

Mark
 
Hey Mark,

Yeah, I was afraid that Gmax might not have the sweep modifier. Its too bad... when lofting every single line one at a time, my fingers would literally cramp up after 200 of them. What a pain!

If you ever decide to step up to 3ds Max, the sweep modifier lets you "loft" all of your lines at once with about 3 clicks. Worth the price of admission if you ask me. lol!

About breaking up the pavement... I typically draw my polys around areas of similar color or seam orientation. That way, I can easily control what texture goes onto which poly and the results are very realistic. All without going nuts in Photoshop trying to create custom textures for every corner of the airport.

I've attached a pic that show kinda what I mean.

Regards,

Nick

WPAFB_3.jpg
 
That looks beautiful, Nick!

I understand about breaking up pavement sections for asphalt vs. conrete, etc., but I guess my question is: say I have a runway, and I want to bring a taxiway entrance up to it. What is the best way to "attach" the taxiway polygon to the runway polygon (or to other taxiway segments)?

Also, I notice that you have "shoulders" or edges on your taxiways and runways. Are those separate polys, and if so, again, how do you attach them to the taxiway? (I assume that you don't just place them close to each other, but you know what happens when you assume :)).

Thanks for sharing your techniques. By the way, what airport is that you are working on?

Mark
 
Hi Mark,

Thanks. It's Wright-Patterson AFB.

About how to "connect" the polys...depending on the circumstances, you don't really have to at all. To use your example, a taxiway intersection with a runway, you simply make sure that the vertices of the taxiway poly line up with the edge of the runway. They're not physically connected at all.

The best method I can suggest is to move your taxiway verts using the appropriate axis constraint, and use the vertex, mid-point, or perpendicular "snaps" to make sure they line up exactly with the runway edge.

To complicate matters, however, when asked about my taxiway shoulders, those are a special case. I originally created this model for another simulator. For various reasons, it was important to keep "layering" to a minimum, so I actually drew each shoulder as a separate poly with verts that were co-located with the taxiway itself.

Now, when I say co-located, I don't mean the "crash the compiler" type. They're totally separate polys, I just used "vertex snap" when creating the shoulder in order to make sure there were no gaps in the pavement.

All of that being said, in FSX (or FS9), layering isn't a huge deal, and it would save you many polys if you simply created the shoulders as a wider (but full-width, single) polygon, and simply layered the taxiway poly on top of it with the ADDCAT command in the ASM code.

Does that make any sense at all?

Basically, I went through the extra (and for MSFS, unnecessary) step of making sure that no two polys actually sit on top each other. With the obvious exception of the taxiway/runway markings...but thats neither here nor there. ;)

Regards,

Nick
 
Nick,

Well, that sounds easier than I thought! Now I just need to get my 57 MB background photo into GMAX without hanging my machine!

Ah, Wright Patterson AFB. My first flight on an airliner (a UAL 727-100) was over Memorial Day weekend 1976, ORD to Dayton to see the Wright Patterson Air Force Museum. That's one of the memories that are responsible for trying to make a back-dated ORD for FS! ORD's 14R/L approaches went over my house as a kid, so I've gotten into RetroAI to recreate all those great planes of my youth.

Thanks so much for sharing your knowledge, Nick. I'm sure I'll have more questions along the way, if you don't mind!

Mark
 
Yeah, the museum is a fantastic place, and anyone who's attending the Avsim FANCON this year will be in for a treat. I live about 2 miles from WPAFB, and I head to the museum several times a year.

I like the sound of a "retro" ORD. I can't wait to see what that looks like.

Don't sweat the questions...I have about three other threads running here where I'm the one asking the questions. While I spend a lot of time modeling, I've spent very litle time actually getting my models to work in MSFS. I'm still a newbie at manipulating the pipeline between Max 8 and FSX. So there may be times where I'm totally off my rocker when it comes to FS specific advice. ;)


Nick
 
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