Visually-Pleasing Stereoscopic Imagery for Design Visualization Jason Walter Software Developer – Autodesk Consulting

Course Agenda 13:00 – 3:20 Why Stereo? Human Perception 23:20 – 3:40 Hardware 33:40 – 4:00 Digital Camera / Stereoscopic Cameras 44:00 – 4:25 Tips & Tricks 54:25 – 4:30 Questions & Answers

Why?

Better tools & technology exist “Stereoscopic Cinema failed in the 50’s because artists did not have the proper tools to produce content.” – Lenny Lipton (CTO Real-D) “Stereoscopic films take 15% more money to make. They require re-thinking the film pipeline.” – Jim Mainard (DreamWorks Technologist) “Making stereoscopic content is hard! There is little talent in the industry and we are expected to produce content for the technology.” – Phil McNally (Stereographer).

A better story

Money to be made “We have seen a trend where people are willing to spend more money to watch 3d content than 2d content” – Bob Igner (CEO Disney) “By 2010 there will be 3000 theatres equipped to project stereo content. Today only 700 exist.” – Lenny Lipton (CTO Real-D)

Industry is motivated “[S3D] is the most exciting thing that has happened in the business since I have been in the business.” - Jeffery Katzenberg. “I'm just going to do everything in [stereoscopic] 3D now. I'm going to shoot my daughter's birthday party in 3D.” – James Cameron

Why Stereo for Design Visualization?

Experience > Differentiate > Sell

Display a unique perspective for each eye. Visual processing center reconstructs in 3D. It is just a perceptual trick. Technology Overview

Image from Jim Gasperini

Human visual system is very sensitive bad stereo Traditional photographic tricks do not work Compositing and editing must take in account depth Not a strong understanding of stereo by artists Challenges

Perception of Depth

Depth Processing Stereopsis – depth perception using two point of views Interposition – object A is on top of object B Light and Shade – the shading of an object can provide depth cues Texture – differences in texture orientation Parallax – relative motion of different objects Perspective – vanishing points Size – relative size of objects

Perception of Depth with Stereoscopy (Put your glasses on now)

Hardware

Anaglyph  Cheap  Easy to find  Loss of color fidelity  Very little eye fatigue  Good for large audiences  Requires no additional hardware  Suffers ghosting

Glasses  Active  No ghosting  Eye fatigue  Expensive  Darker Picture  Good for small audiences  Passive  Ghosting  No eye fatigue  Cheap  Full Color  Better for large audiences

Checkerboard Format  Samsung DLP 3D Display

Horizontal Interlace  Hyundia 3D LCD

Full Resolution Displays  Tru3D Display (Passive)  120 HZ CRT Displays (Active)  120 HZ LCD Displays (Active)  REALD Z-Screen (Passive)  Projectors (Passive / Active)

Projectors / Cave  Christie / REALD Z-Screen  Dolby 3D  IMAX

Camera / Stereoscopic Cameras

Camera Model – Low level Confidential

Camera Model – Digital Parameters Confidential

Mapping Digital Parameters to Computer Friendly Version Confidential

Example of shifting & importance Film center is not necessarily aligned with optical axis. The frustum can be skewed. Confidential

Principles of stereoscopic cameras 1. It is two cameras, not one camera 2. Each camera is offset by a fixed distance – interaxial distance 3. There is a point of focus – zero parallax Confidential

Stereoscopic camera models  Toe-in – rotate the cameras inward  Off-axis – shifting the frustum  Parallel – focus at infinity Confidential

Off-axis computation from base camera model Confidential

Toe-in Versus / Off-axis

Vertical Parallax

Parallel Rigs  No control over convergence  As if viewing through a window  No need to worry about divergence  Easy stereo

Off-axis (Put your glasses on)

Converged (Put your glasses on)

Parallel (Put your glasses on)

Comparison (Put your glasses on)

Maya Stereo Demo

Beyond Maya’s Model  Maya’s stereoscopic camera is the base model  Provides the core parameters and calculations  Does not prevent perceptual issues  API to augment camera model  Abstraction between visualization hardware and camera Confidential

Maya Stereo API Properties  All cameras have a root transform – stereo rig root  Camera shape is directly below the root  Data driven approach  Attribute control how to find the data  stereoRigType  centerCamera  leftCamera  rightCamera Confidential

Stereo API Creation  New rigs are created via a callback script  Callback script can be MEL / Python  The callback must specify the ‘stereoRigType’  Returns the [root, left, right] cameras Confidential

Simple Stereo Rig global proc string[] stereoCameraSimpleRig() { string $basename = "stereoCameraSimple"; // Create the root of the rig // string $root[] = `camera -name $basename`; string $left[] = `camera -name ($basename+"Left")`; setAttr ($left[0]+".tx") -6.32; parent $left[0] $root[0]; select -r $root[0]; return {$root[0], $left[1], $root[1]}; } stereoRigManager -add "simpleRig" "MEL" "stereoCameraSimpleRig"; Confidential

Guidelines

Two Degree Rule  No two pixels should be separated by more than 2 degrees  Maximum tolerance for human visual system (put on your glasses)

Two Degree Rule < 2 Degrees

Maya Degree Calculator - DEMO

Floating Window  Solves interposition issues for objects in front of ZP plane.  Artificially introduces a 3d window.

Floating Window

Maya Floating Window Calculator DEMO

Layered Cameras  Single stereo setting does not work for entire scene  Need to segment the scene  Break up into multiple layers and composite the result.

Layered Cameras – Maya Setup

Layered Cameras – Toxic Setup

Viewer Distance / Screen Size  Stereo effect is dependent on  Screen Size  Viewer Distance  Need to accommodate for both.

Ghosting  Occurs in areas of high contrast.  Hard to avoid with passive setups.  Technology is getting better.  Active is the best way to avoid.

Conclusion  Perception of Stereo  Hardware  Camera Model  Stereo Camera  Common Problems

Questions