Thoughts on using GPL licensed airport data from a different flight sim?

I recently noticed that all 36.5 thousand airports on an AFS2 competitor's scenery gateway are GPL licensed. If you download one, there's a file named "copying" that includes the full GPL licence.

There's no legal ambiguity about this, it means you can use, modify and redistribute it as long as you include the GPL licence and stick to its terms.

It's also not revocable. That version of the file has been released under the GPL so can't now be restricted.

The airports usually have taxiways hand drawn and many other features hand positioned. It's pretty rich data. The file format is open and well documented.

There's nothing to stop someone downloading all 36k airports and writing something to convert them to AFS2 format.

Thoughts, opinions, concerns? or

Quote from Spit40

That's the tricky bit !

Without a doubt. Not sure if it's even possible in a meaningful way, but knowing that all the data is legally free to use got me thinking.

Hardest part would be parsing the binary DSF file and mapping the "competitor" xref objects to AFS xref objects (which are far less numerous).

Quote from flightxtreme

As long as we cannot size objects this does not lead far, I guess.

Well, there are two parts to a "competitor" airport:

The base airport data: location, tower, runways, papi, lighting, taxi ways, ATC, view points etc.

The xref object positions

The base airport data is definitely useful I believe.

The xref stuff is trickier because you don't know if their "generic_office_block" is the same size as an AFS one. Having said that, planes, cars, trucks and trees should be the same-ish, so there's still some value there.

It's something I might play around with when I'm having an ADHD moment anyway.

Update

I spent a few hours doing a proof of concept of this. I wrote parsers for the two file types so I now have all the airport data in a usable format.

I could then write a very simple TSC of the airport (no graphics runway etc). Not much but it's a start.

The data is fantastically detailed btw; even down to what signs by the side of the runways should say and where exact lights are.

Where X-P is rendering the runways, taxiways, decals, sign and light geometry on-the-fly, AFS expects pre-made models of everything.

The solution (and the hard part) is therefore to dynamically output the TGI files as part of a convert process.

It's definitely complex, but think it's worth exploring further. It's only maths after all.

Will keep spending a few hours on it here and there and see what I can come up with.

There must be hundreds of thousands of man hours of work in that data. It's a shame not to tap into it somehow.

Quote from vogel69

I know that IPACS give a C++ .dll library to Arno in order to handle the binary .TGI format ... It seems to me that Arno because the ASCII format was enough for him ? or for lack of knowledge about wrapper ? or for lack of time ? has not yet written wrapper for this dll but it could be interresting to look at that side? If you have the skill to write a C # wrapper it would be great ...

Yeah, I asked them for the DLL directly. I'm not sure what the acceptance criteria is. If it's been shared with one developer it should just be in the SDK, but there you go. I could definitely write a C# wrapper, which would be useful.

Dynamic TGI would be a good fit for creating small things: simple buildings and signs, but I came to the conclusion that plotting vertex data of the airport ground poly purely in code is too complex. You'd end up writing part of a 3D engine to do it. Single runways are easy, but you have to deal with multiple overlapping runways, adjoined taxiways, then sub-object materials in that combined poly.

My next attempt is for my C# to output a Blender or Max script that draws the ground poly. This seems much more achievable and a proof of concept of that checked out, I could draw a simple rectangle of the correct size representing the runway.

If there was a full Blender export plugin for TGI I'd go with that as Blender's scripting interface is much nicer. (And anyone can download and use it).

I need sub-object material export though, and I don't know how to do that in ASCII TGI (and nor does Anro's code).

That probably leaves outputting a Max script to draw the airport ground.

Anyway, plenty to tinker with and test.

When I have something worthy of viewing I'll post it here.