Archive for the ‘Air Taxi’ Category

posted by admin on Nov 4

Starting Wednesday I will be out of the office - Lori and I are going on a 2+ week trip to India!

So first, the obvious: your comments to the blog won’t show up until I get back and can moderate them. Similarly, I will be even less on email than I am now. I am trying to dig out my tech support emails as much as possible before I go!

I will announce this before I go: I finally got an end-to-end render of a global scenery tile using CGAL 3.3.1. Andrew did the original work on this, modifying parts of the scenery generation code to handle his NZ scenery. I’ve been working on the rest of the algorithms and finished it today.

This doesn’t mean very much immediately, but it…

  • Will fix the instability bugs in MeshTool.
  • Will address missing antennas and obstacles in the global scenery.
  • Provides a solid basis for building scenery out of just about any kind of data.
  • Provides a bunch of nice tools for writing better algorithms, which means nicer looking scenery.

The next steps will probably be to create a new release of the tool set, including perhaps a bug-fixed Mesh Tool, etc.

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posted by admin on Nov 4

Previously I have blogged about a key choice in file format and scenery system design: will the file format be “specification based” or “reality based”.

Specification based: the format has an exact interpretation of the data. OBJ is an example of this…the format describes triangles and there is only one interpretation of what that triangle could be.

Reality based: the format models real-world concepts; the correct interpretation is “as close to the real world as possible.” The nav.dat file is like that.

I have been reading the OpenStreetMap Wiki and hit upon something I didn’t realize: you can’t use copyright to protect a derived work from a file that simply contains a list of facts!

Now I am a programmer - I am used to writing code, slapping a copyright notice up top, and assuming that it’s now mine…heck, I’m the one getting carpel tunnel from typing it out. But consider the nav.dat file; it contains a giant list of frequencies for navaids. It’s a fact that the BOS VOR is 112.7. Is my mentioning of that fact in this blog a derived work of the nav.dat file? Of course not, and it’s a good thing too because otherwise we wouldn’t be able to state facts without IP conflicts.

The OSM guys believe that they need to change their license to something weirder than the CC-BY-SA license they have now because the CC license uses copyright, you can’t copyright facts, and OpenStreetMap is really just a huge collection of facts.

Now at this point I’ve written six paragraphs too many without the obligatory “I am not a lawyer.” I am not one. And I must admit, my biggest concern with all of this is that it gets confusing and hard to interpret, and I’d be perfectly happy if there were only 3 or 4 licenses out there for everyone, you’d pick your favorite flavor, and everyone would know what it means.

Suffice it to say, it never occurred to me that a criteria of a file format might be “protectability” - that is, does the file format allow an author to specify something other than facts, so that it is elligible for copyright protection?

If you are an author, the good news is: pretty much all of our file formats would meet that criteria:

  • OBJ and DSF are essentially 3-d modeling containers (DSF is just a damned wierd one).
  • Images are copyrightable, so that takes care of your textures.
  • Plugins are code, clearly copyrightable.
  • ACF files contain, among other things, 3-d models, see the first point.
  • Apt.dat would be the format most at risk of “factualization”, but I think you could argue that the arrangement of bezier curves and attributes is more of an artistic 3-d model than a statement of fact.

But who knows, I am not a lawyer.

(Oh yeah, this whole article is written from an entirely US-centric viewpoint…I am even less qualified to speak of such things outside the US than I am here at home.)

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posted by admin on Nov 4

I’m never quite sure about naming names. There are users whose contributions to X-Plane and its scenery system have been immense - we wouldn’t have what we have without them.

But I don’t want to make the decision to blog for anyone else - this blog is part of Laminar Research’s communications to our users, and I don’t want to set up content that leads our paying customers toward third parties who may not want the extra questions/attention.

So I guess for now what I’ll say is this: the work I discuss here on this blog is not a solo effort - I have had the good fortune to collaborate with some really good people, and it has made X-Plane that much better of a flight simulator.

To everyone who has helped me with the scenery system: thank you!!

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