Autostereo 3D view (three dimensional client)

Instructions for creating a 3D view:

TO CREATE THE STEREOGRAPH ON THE COMPUTER SCREEN

Use two camera positions to create two views of Second Life. The two views should be separated by several degrees of rotation in the horizontal plane. The axis of rotation should be a point close to the cameras - I suggest the avatar itself as this is an always-present point of reference for the user.

The angle should be set to replicate the angle of the eyes when crossed halfway between the monitor and the user, around 10 degrees.

Divide the screen into four vertical strips, from left to right. Call these strips A, B, C and D. Whilst the effect can be achieved with two images, the idea is to create a pattern that repeats across the width of the screen. This significantly aids the user in getting a clear angle for their eyes. The contents of each of these strips should be as follows:

A - contains the RIGHTmost camera image.
B - contains the RIGHTmost camera image.
C - contains the LEFTmost camera image.
D - contains the LEFTmost camera image.

Experimentation has shown that changing the A and D pictures to try and cancel out the outermost images, for example by inverting the image, greyscaling or rotating the hue map just results in distracting contrast away from the centre of the stereograph. So don't try!

TO ACHIEVE THE STEREO VISION EFFECT

The simplest way to describe what the user is doing is to slightly cross their eyes, as if looking at something halfway between the user and the screen, but keep the screen in sharp focus. What follows is a guide for those who find this difficult.

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Sit further back from the monitor than usual, at least TWICE the distance that you can comfortably focus your vision on an object (typically, the distance to your monitor should be more than 50cm). Place your finger at half the distance to the monitor and look at your finger. Your eyes are slightly crossed because you are looking at a close object.

As with the autostereo pictures that were popular some years ago, the trick now is to change the FOCUS of your eyes, but not the ANGULAR POSITION. Whereas the autostereo pictures needed you to get your eyes aligned with infinity but then focus on the paper, this requires you to keep your eyes aligned at your finger but focussed on the screen. To do this, make sure that your finger remains a single (but out-of-focus) image, but focus on the screen instead.

You should now see FIVE sharp images across the screen, which I will call V,W,X,Y and Z. W and Y will show the plain camera images, right and left respectively. They should be pin-sharp and 2D; they are your guide to focus. V and Z will be a combination of the out-of-focus edge of the monitor and ghosts of the plain camera images; they are peripheral enough to be easily ignored. Crucially the middle, X, image will appear strongly THREE DIMENSIONAL.

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I have only been able to do this with static images taken from the client so far. Okay, the view is effectively 25% of the screen but I imagine that the images produced by moving in the world, animations and so on will create a stunning effect.

Whilst the image itself is 3D, the main issue with this is the user interface. To avoid loss of focus, the UI would have to fit in each of the vertical strips. That requires a high resolution display in order to be able to make out the text.

To overcome this, further experimentation has revealed that the outermost images need only show half of the camera image, increasing the proportion of the display available whilst maintaining enough repetition to keep the user's eyes aligned.

A - the right half of the right camera (split through the avatar), 1/6 of the display
B - the complete right camera image, 1/3 of the display
C - the complete left camera image, 1/3 of the display
D - the left half of the left camera (split throught the avatar), 1/6 of the display

Alternatively, the stereoscopic view could be a separate display option, like "press M for mouselook", you could have "press S for stereo". More essential tools - the right-click segment chooser and the chat interface for example would remain. They would be duplicated in each strip. Many other tool windows would have to be temporarily removed whilst in this viewing mode to reduce clutter.