Three Dimensional CT Reconstruction.

John Wattie and Tim Sheehan

STEREOSCOPY:

Viewing Methods

FREE VIEWING:

   Cross Eyes Version 

   Parallel Eyes Version

RED / GREEN GLASSES

   Grey anaglyph

   Coloured anaglyph

Aortic aneurysm

X Stereo

• You need to [go cross eyed] (X stereo) for the big 3D stereo pairs.
• Your eyes must be on the same horizontal plane before attempting this feat - don't tilt your head.

To go cross-eyed, look at your finger placed about half way to the computer screen, fuse the images, then let your eyes refocus in their own time.

Otherwise look through a [4cm square in a sheet of cardboard,] aligned so each eye can only see the correct picture of the stereo pair.

Or use a $US20 Vivitar card viewer which is made for Vivitar camera prints in cross-eye format. It works on computers too.

U Stereo

• Some prefer to use
  [parallel viewing stereo] (U stereo)
• Smaller pictures are used for that, because most people's eyes will not diverge past parallel.
• U stereo means less resolution on a computer screen, because less pixels make up the picture.
• U format does allow a standard 3D viewer to work - but viewer magnification is not too edifying when the pixels enlarge.

• It may help to put your face up to the computer screen, relax the eyes, then slowly pull back.
•  Keep looking through the screen into the distance.
•  If the separation seems too great for your eyes, move further back from the screen and they will not have to diverge so much.

Colour anaglyphs

Liquid crystal glasses

The image format used for the X stereo version is suitable for liquid crystal glasses using the [Depth Charge program]. With a fast video card, this is a good way to see computer stereo and is supplied with some radiology work stations, e.g. Siemens MRI.