3D Visualizations Best Practices

A member of our team, Steve McQuinn, is a 3D artist, and he has produced some stunning 3D movies for the Tahoe Environmental Research Center.  Below is his primer for 3D visualizations best practice.  It’s still a work in progress, but I hope it slakes everyone’s thirst for insight about 3D visualizations in an informal science setting.

Brief primer on stereo 3D Best Practices

Avoid vertical disparity.

Professional quality non-immersive stereo 3D assiduously avoids vertical disparity between a pair of images. For computer generated stereo 3D, including non-immersive versions of immersive technology, vertical disparity is a result of using a toe-in configuration for the virtual camera rig.

When the axes of two camera positions converge upon a point in a scene, other points that are common to other objects in the scene are relatively shifted vertically in the right and left views. This vertical disparity is impossible for a viewer to resolve, causing eyestrain and headaches. 

The best practice for achieving the convergence of points (zero parallax) that defines the screen plane is to render from cameras with lens axes in parallel alignment, shifting the

consequent right and left images horizontally towards each other to set the desired frame. Thus, vertical disparity is avoided. Please note that this applies only to Stereo 3D, not to immersive head tracking 3D. 

A 50 to 60 degree Horizontal Field of View (HFOV) is optimal.

From thorough testing with focus group audiences, the stereo 3D supervisor for Dreamworks Animation (my friend Phil “Captain3D” McNally) has determined that a wide
angle CG lens equivalent to a full-frame film-based SLR still camera 35mm lens, produces the best combination of 2D perspective cues and 3D parallax disparities. This is about 55
degrees horizontally.

Again, please note that this applies only to locked-perspective Stereo 3D, not to variable perspective immersive 3D.

Wide screen formats are better.

Wide angle fields of view and deep stereo 3D compositions look better with a wide aspect ratio. 16:9 is preferable to 4:3. Binocular vision is optimized for horizontal scope.

Use divergence sparingly.

Divergence occurs when the eyes look away, right and left, from parallel lines of sight. Infinity disparity on a screen of any size is the human eye separation. If very distant image points are separated in two views by a distance greater than eye separation, the eyes have to diverge to fuse those points into a common object. Audiences don’t object to this when the divergent points are not the center of their attention, and the technique is sometimes necessary to achieve creative depth in a scene background, but divergence should be used with caution.

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