Anaglyph (3D): Difference between revisions

This wiki describes how to use the '''stereo vision''' or '''[http://en.wikipedia.org/wiki/Anaglyph_image anaglyph images]''' ability of [[OpenSceneGraph]] and let you experience the [[FlightGear]] world in 3D. Another excellent example and simple application of FlightGear's flexibility and realism.

'''Important Notice:''' Even though it might not pose any danger, try avoiding excessive use of different color paired glasses, and after your flying sessions with the glasses or whatever, let your eyes and brain rest for a while before starting to sew, chop meat, drive 160mph, dig the garden etc.

As you might know or not, FlightGear migrated graphics functions from [[PLIB]] to [[OSG]]. [[FlightGear 1.9.0]], released Decemeber 22, 2008, marked the release of the OSG version of FlightGear. As of August 2010, most recent stable version of FlightGear uses OSG. For those who are unaware of OSG, it is an open source high performance 3D graphics toolkit.

Stereo vision exploit the human perception by showing a 3-Dimensional image on a 2-Dimensional surface. To understand stereo vision and human judgement of visual distance (that is how we keep visual separation from the traffic), make the following small experiment. While reading this text, close your left eye and then right eye, open left. When you alternate your view, it'll feel like the monitor is moving to little left when you observe with right eye, and vice versa. This situation gives us two different images. Now imagine you took this two "slightly" different images and match it such that each eye sees what it is supposed to see. There are not so many but quite a few ways to achieve this separation. And OSG is capable of doing all of this. Now apply this to your short final 28R at KSFO!

[[File:Anaglyph-glasses.jpg|thumb|Red-Cyan pair of 3D glasses.]]

For this experience, you will need  

The easiest and shortest way for users of FlightGear up to version 2.0.0 to experiment with this is to follow the procedure below (quick start). Later versions (including GIT sources) have native support for setting the relevant properties at runtime from a dialog box at View->Stereoscopic View Options.

# Start the [[FlightGear Launch Control|FlightGear launcher]], select your aircraft and select your location.

# On the next screen, click "Advanced" just above the "Run" button.

# On the new window, titled "Advanced Options" highlight the "Environment" from the list on the left

# Now, you will create new environment variables, click "New" and type <tt>OSG_STEREO=ON</tt>, then again click "New". At this point you should be seeing "OSG_STEREO=ON" on environment list.

The result should be something like shown on the right.  

   SET OSG_STEREO=ON

Thanks to [http://flightgear.org/forums/memberlist.php?mode=viewprofile&u=1650 someguy] (not some guy, a FlightGear forum member!) for providing Mac OS X instructions. And here is the related [http://www.flightgear.org/forums/viewtopic.php?f=19&t=9222&p=93141#p93141 post]with more screenshots.

   </plist>

A brief explanation of the values we gave for the environment variables goes like this. This info comes directly from the [http://www.openscenegraph.org/projects/osg/wiki/Support/UserGuides/StereoSettings OSG Stereo Settings] page.

(Any practical application sample of Vertical Split?)

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The very final part of the OSG stereo view options consists of few variables that accommodate the device specific issues and finally allows you to set straight look or cross-eyed look (not advised) options.  

'''OSG_SPLIT_STEREO_VERTICAL_EYE_MAPPING''' works the same way as horizontal mapping, displaying upper and lower images respectively. The string variables are LEFT_EYE_TOP_VIEWPORT and LEFT_EYE_BOTTOM_VIEWPORT, which are quiet self-explanatory.