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apt.dat version 850

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Re: apt.dat version 850

Postby psadro_gm » Fri Sep 09, 2011 2:00 am

So, this is what it looks like when you run out of primitives in the .btg file - water landings....

Image

Granted - I was splitting curves into 16 segments. I'm going to make far fewer soon, and then try to create strips after tesselation
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Re: apt.dat version 850

Postby mike4lin » Tue Sep 13, 2011 11:14 am

Looking forward for this much appreciated change. I could test with my Suisse04 sceneries as they all need 850 format, simply pm me. Thanks for your work.
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Re: apt.dat version 850

Postby psadro_gm » Tue Sep 13, 2011 1:02 pm

It's going to be a few weeks before another update. I've run into a couple serious issues that need to be debugged. I'll take them one at a time.

1. I've run out of physical memory (I have a 7 year old computer with just 1GB RAM) - So far, the design has been naive in memory management. That needs to change now, as my latest genapts run took 31 hours to complete katl. Lots of stuff to be done, here.

2. hole tessellation - it's not working correctly, and causes the trianglejrs lib to crash sometimes.

3. bad data detection. runway 8R at KATL has some weird taxiway data problem. It's even visible in WED. I don't have a full copy of x-plane to see if it is handled there, but I end up creating some polys crossing several tiles. Results in a really long polys...

4. Running out of poly. I'm not 100% sure this is the case, but I have noticed some missing polys in the full decode. If I remove maybe half the pavements from the input, they show up fine.

5. Very steep safe_base. genapt creates a base poly (small offset from all runway / taxiways) and keeps the height for this consistent with the height smoothing function. safe_base is further out, and is consistent with the underlying srtm data. So this region trasitions from the smooth airport to the noisy srtm. Mine sometimes looks very steep.
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Re: apt.dat version 850

Postby f-ojac » Tue Sep 13, 2011 5:57 pm

A long way ahead, lots of things to debug, but a big step forward if you succeed, and the first results are impressive. Wish you all the best for your hard work I am sure everyone welcomes.
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Re: apt.dat version 850

Postby psadro_gm » Sat Sep 17, 2011 3:25 pm

Managed to get memory usage under control. The biggest issue was caused by the expand poly algorithm to build the airport base and safe-base. When the math blew up, very bad polys were generated, causing VERY large airports to be created. This has been mostly fixed. In KATL, there is still just one pavement poly (#108 of 191) that still blows up.

There are also several polys that have missing triangles (you can see them in the screenshot as blue sky) That is second on my list.

Third on my list is sometimes the skirt polys between base and safe_base have the wrong winding, showing sky that should be obscured by the skirt.

Once these three issues are fixed, I plan on adding the parser as a new exe in a terragear repository.

Then correct texture coordinates for pavements need to be generated. This shouldn't be too difficult, as the texture for pavement doesn't bend, and the heading for each pavement is in the source data.

Here's a scrren showing the current status (with poly#108 removed so it doesn't blow up)

Image
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Re: apt.dat version 850

Postby psadro_gm » Sun Sep 18, 2011 4:43 pm

I've found the problem with missing triangles. I have a temporary fix, and ideas for a much better, but still imperfect fix.

The problem is the removal of a co-linear vertex in TGPolygon reduce_degeneracy. The donut shaped poly is actually made of a single contour (if the editor created the hole with a second contour, there would be no issue). One of the vertices closing the donut is co-linear with the other end. If I do not remove this co-linear vertex, the triangulation routine becomes confused, and simply generates a big circle with no hole.

A better fix would be to nudge the vertex a bit perpendicular to the segment it co-linear with. Determining which direction to nudge it in is a bit of a challenge, but doable.

My quick fix is to check for degeneracy and dupe vertices before clipping against the accumulated polys, and generating the bases. This at least gives me a full surface with no holes.

I think I'm going to start to merge this in to a terragear repository so others can easily work on the code, as some have offered help.

Once in, I can write a few bugs I know about (the other having to do with less than ideal base polygon shapes when dealing with small angles...

Image
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Re: apt.dat version 850

Postby psadro_gm » Sun Sep 18, 2011 9:48 pm

After fighting with gitorious.org and ssh keys, I finally got this into a properly cloned terragear repository. Before hanging it up for the day, I started looking into the texturing, and it was very simple:

Image

Next up is the fun part - the linear features that are co planar with the taxiway polys :)
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Re: apt.dat version 850

Postby skyop » Sun Sep 18, 2011 10:23 pm

Looking good; if this really ends up in FlightGear, that would be amazing! :)
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Re: apt.dat version 850

Postby mdsmith2 » Sun Sep 18, 2011 10:25 pm

This is incredible! We've needed this done in FlightGear for a long time.
You sir, are exactly the kind of developers we need for this project. Good work *claps*
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Re: apt.dat version 850

Postby f-ojac » Mon Sep 19, 2011 11:15 am

Big applause, I must admit I am stunned by both the quality and speed of your work. Looking forward to seeing this implemented as a standard FG/terragear feature. It will be great to rely on the 850 format.
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Re: apt.dat version 850

Postby Gijs » Mon Sep 19, 2011 11:24 am

As I tend to say, some things are justified by a single word. Well, in this case I'd better be two:

Wow Wow!!
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Re: apt.dat version 850

Postby longfly » Mon Sep 19, 2011 12:12 pm

Ok, please read the last 4 posts again and then you know what I think about your excellent work! :P

Really great work!
Thanks a lot - Longfly
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Re: apt.dat version 850

Postby VaLeo » Mon Sep 19, 2011 5:02 pm

:shock: Amazing!
I dream about it for several years ...
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Re: apt.dat version 850

Postby ot-666 » Mon Sep 19, 2011 6:00 pm

Indeed… brilliant work. :D
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Re: apt.dat version 850

Postby Zan » Tue Sep 20, 2011 9:21 pm

You, sir, are doing an excellent job! I don't understand how you figured out terragear/genapts so quickly. I've looked into it a few times, and couldn't find a place to start.

Great, keep up the good work! Can't wait to see this in a release!

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