The Overlay System

I have received a number of emails from people trying to use DSF2Text (a fixed version is coming real soon). From this I can only guess that people are trying to customize the global scenery!

We are working on the “overlay” system – when this is a little more hammered out (a week or two) I’ll try to describe it in detail. But the basic idea is to allow additional DSFs that contain only objects and other 3-d “clutter” to be superimposed on the basic terrain, adding to or replacing the default objects.

This would have a few benefits:
– Small distribution size for custom airports and other such object-based scenery (because you don’t have to redistribute our mesh).
– No legal limitations (since you don’t have to copy our scenery).
– Since many overlays can go on one base, a user will be able to install a number of custom airports.
– Probably the small overlay DSFs will be easier to work with – a 25 MB DSF makes an insanely huge text file in DSF2Text.

Anyway, this is all very experimental; I will have more info soon, but all of this is subject to change. For now I can only say with certainty that we are working on this problem!


One Frame Per Second

Let me commit this to writing: I WILL get new tools (DSF2Text, AC3D Plugin, etc.) out this week!!

The rendering engine has been taking up all my time this week. To give you an idea, I spent part of the weekend and Monday rewriting the way we handle physics interactions between the simulator and the graphics rendering engine…only to find the new code improved framerates by…one frame per second!

When I complained to Austin about this he said, “good, I’ll take every one fp I can get”, and I realized…this is how we make progress forward. If after a week we’ve got a 5 fp boost, that’s definitely a big help to a user who is getting fog now.

(Of course, not all fps are created equal; a frame per second is the reciprical of the time the sim is taking, so a 1 fp improvement when the sim running at 20 fps is a huge victory; a 1 fp boost when the sim is running at 90 fps is negligable.)

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New Scenery Framerate and Bugs

Wow…I went up to Boston for a weekend and came back to find a flood of email regarding the new scenery, a few hundred posts on the tech list, and blog comments and forum posts. If you didn’t hear from me, please try a direct email; if that didn’t work, please bear with me…I am on the verge of email bankruptcy.

Most of the posts have been on the subject of bugs and anomolies in the scenery and framerate problems. A little bit on both.

Bugs: bugs in the global scenery fall into the catagory of artwork problems and DSF problems. For example, the most common report I’ve seen is of the big green and brown patches in European urban areas. This is due to a bad text file (a typo – my fault!!) for the terrain artwork. This particular bug should be addressed in X-Plane 830 via an automatic update. Generally where the artwork is bad, we can provide a new artwork file in the update to fix things.

Where the DSF itself is bad there’s not much we can do. Usually bad DSFs result from bad source data. This is a place where custom scenery will have to fill in the gap and provide local detail and customization that we can’t provide with the very broad brush of global scenery.

We also have some algorithm limitations and data limitations. Non-CONUS road data is quite inaccurate, and CONUS road data does not have overpass information; both are a source of strange roadways. If you see a bug, please file a bug report! I can’t keep up with forum posts to find potential problems.

Performance: X-Plane WILL run slower with the new scenery – that’s because there’s more data packed in there. Simply put I do not think we could make it look as good if we cut down the polygon counts to US DSF or ENV levels. I am working on engine improvements in X-Plane, so 830 may provide some relief, but please understand: X-Plane 821 is not slower than 820 – it’s just doing a lot more work to show you each frame!

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A “real” Scenery Blog

I am converting the “scenery blog” to a real blog, meaning one that uses real blog software for RSS feeds, trackbacks, comment posts, all that good stuff.

A brief intro: I work for Austin Meyer on X-Plane, a cross-platform flight simulator based on real physics, developing the scenery system, scenery engine, 3rd party development kits, and the algorithms used to create the default scenery.

We just shipped the new “global scenery”, a rendering of the entire world from 54S to 60N using SRTM2 data. Sergio (our lead artist) has posted some screenshots here. I’ll try to post on topics of interest to scenery authors and X-Plane users.