Estimating Ambient Obscurance in Real-Time / Reimagining Textbooks in the Age of the Tablet

Abstract

The real-world phenomenon of ambient obscurance (AO) produces perceptually important illumination effects such as darkened corners, cracks, and wrinkles; proximity darkening; and contact shadows. Artists have long recognized and mimicked this effect in traditional media. Previous algorithms for computing AO for rendered images of 3D scenes tend to take minutes per frame or produce results that significantly diverge from real images.

In the first part of this talk, I'll present the new "Alchemy" AO algorithm developed at the Vicarious Visions game studio that produces plausible results in a few milliseconds on Xbox360 or PC GPU. It is based on a new derivation of screen-space obscurance for robustness, and the insight that a falloff function can cancel terms in a visibility integral to favor efficient operations. I will demonstrate that Alchemy AO has several desirable properties: it creates contact shadows that conform to surfaces, captures obscurance from geometry of varying scales, and provides intuitive appearance parameters for artists.

I will conclude the talk with a radically different topic. I'm currently working on The Graphics Codex, a non-linear education resource packaged as an iOS app. It borrows presentation ideas and reader workflow from traditional textbooks, Google, Wikipedia, professional texts, and reference documentation. Next year, students in the Williams College computer graphics course will be issued iPad tablets to use apps like The Graphics Codex in the classroom. I'll discuss the usability design and systems work behind The Graphics Codex and invite discussion on its pedagogical application.

Bio: Morgan McGuire is an assistant professor of Computer Science at Williams College. He received his PhD from Brown University in 2006. Prof. McGuire is the co-chair of the 2010 ACM Symposium on Non- Photorealistic Animation and Rendering, a member of the Journal of Graphics, Game, and GPU Tools editorial board, and the lead author of Creating Games: Mechanics, Content, and Technology. He previously co- chaired the ACM Symposium on Interactive 3D Graphics and Games in 2008 and 2009.

He has contributed to many commercial products including the E-Ink display for the Amazon Kindle, the PeakStream high-performance computing infrastructure acquired by Google, the Titan Quest role playing game, and the Marvel Ultimate Alliance 2 video game for Xbox 360.

Prof. McGuire's current research spans computer vision and video games. He's using video cameras to help computers understand the 3D world around them, and is investigating new design methods for video games increase interactivity and engagement as well as improving 3D rendering. He incorporates these research ideas into the computer graphics and game design courses that he teaches at Williams College. He is currently working on a new Xbox 360 and Playstation 3 game at Activision and an advanced computer graphics textbook.