Jim McCann

(Sometimes known as James L. McCann)
Picture of Jim Picture of Jim
Picture of Jim Picture of Jim
E-Mail: jmccann (at cs dot cmu.edu)
Phone: (412) 400 three one nine nine
CV: pdf format
Address:
616 East End Ave.
Pittsburgh, PA 15221

About

This page is a monolithic presentation of the research software and projects I'm associated with. If you are interested in my personal life, games, or terse ramblings, please visit my web server at tchow.com.

I was a PhD student in the graphics lab advised by Nancy Pollard. Having mostly graduated in August 2010, I began a postdoc at Adobe's research lab in Boston. In October of 2012 I moved back to Pittsburgh to work full time on writing video games, creating Rktcr [for Windows, OSX, and Linux] and Rainbow [for iOS and Android]. In February of 2014, I took a job with Disney Research Pittsburgh, mainly because they offered me the opportunity to make real things with my research.

Research-wise, I'm interested in systems and interfaces that operate in real-time and build user intuition; lately, I've been applying these systems to game design and the creation of physical objects.

My brother Mike McCann is currently a graduate student at Carnegie Mellon University. His web page design seems familiar.

Research

NOTE: Nancy Pollard, being my adviser, should be considered an implicit collaborator on all of the pre-2012 projects listed below.

Dynamic Sprites (2012-2013)

With Ben Jones, Jovan Popovic, Wilmot Li, Adam Bargteil
dynamic sprite ragdoll versus dynamic sprite crates betwixt dynamic sprite beams

This project (which began when Ben was an intern at at Adobe) describes a hybrid of traditional sprite sheets and physics-driven animation. These "dynamic sprites" try to keep their large-scale deformations close to an artist-authored pose manifold while allowing physics to control both their fine-scale deformations and overall trajectory.

A paper describing this work will appear at the Motion in Games conference in November, 2013. For more information, see the project page.

Physics Storyboards (2012-2013)

With Sehoon Ha, C. Karen Liu, and Jovan Popovic
interacting with our small prototype

In this intern project at Adobe, Sehoon designed a system for tuning physical (and pseudo-physical) simulations. Given a storyboard consisting of example behaviors and objective functions, this system is able to find parameters that optimize the objective, thus automatically tuning the game or simulation.

We demonstrated this system on three games ranging from the classically-physical (an Angry Birds clone), to arcade-physics (a top-view racing game), to pseudo-physics (an RTS).

This work appeared at Eurographics 2013; see the project page for more information.

Align and Distribute Behavior (2012-)

Graphics programs provide align and distribute buttons that do something (often based on object bounding boxes), but does this thing match what people do? I performed a series of Mechanical Turk experiments to answer this question. In each experiment, turkers were asked to align an object horizontally or vertically with two other objects, or distribute the space between objects evenly.

These experiments suggest that perpendicular distance (for distribute) and center of convex hull (for align) more closely match what turkers do than current bounding-box methods. (Though this does not imply that these are better choices for a graphics program.)

This work has not been published. If you'd be interested in continuing the project, let me know.

Lightfield Painting (2012)

With James Tompkin, Samuel Muff, Stanislav Jakuschevskij, Jan Kautz, Marc Alexa, and Wojciech Matusik
interacting with our small prototype

While in Boston, I occasionally walked over to Disney Research and worked on this system to use a lenslet array for simultaneous, co-located input and output of 3D lightfields. My main contribution was a solid-surface renderer (used in our demo, not shown in video) that worked by rendering a grid of 20x20 views and then carefully multiplexing them for the lenslets in a second pass.

We showed a 4-projector system (larger than that shown to the right) in SIGGRAPH 2012's Emerging Technologies showcase. Here's a video from the floor; and here's our video.

Soft Stacking (2009-2011)

softly stacked smoke

Soft Stacking is the continuous follow-on to Local Layering. It is to Local Layering what continuous alpha is to a covered/not-covered bitmask. With the techniques outlined in Soft Stacking you can represent and edit multiple stacking orders inside the same pixel.

This work appeared, in part, in my thesis. A revised version appeared as a paper at Eurographics 2012. The paper and video are available on the Project Page.

Image Editing and Creation with Perception-Motivated Local Features (2008-2010)

In my dissertation, I provided examples of systems where -- by choosing carefully what to make local -- standard 2d graphics tools were revised and improved.

Mid-level Fluid Control (2008-2010)

With Zeyang Li, Alfred Barnat
motif-controlled smoke

In the Spring semester of 2009 I mentored two undergraduates working on a new idea I had in fluid control: mid-level control -- where features of fluid neighborhoods are controlled, but global pose is free to evolve. They started with my sketchy vision and added the ideas and research required to create a working prototype.

This work appeared in a poster at SCA 2009, and 2010; and will appear as a paper at GI 2011. See the project page for more details.

Local Layering (2008)

locally layered pants

In graphics, we often stack up images like animation cels -- using one global order, even when layers have transparent holes and irregular shapes that would allow them to twine about each-other if cut from, e.g., paper. In this project, I present a simple method for realizing such paper-like stackings, and introduce a set of navigation primitives which are both correct and sufficient.

This work appeared as a paper at SIGGRAPH 2009. The paper and video are available on the Project Page.

Real-time Gradient-domain Painting (2007)

gradient illustration

I've designed a system to allow for brush-based gradient-domain editing with real-time feedback. This gives you a real gradient-domain clone brush and -- more interestingly -- lets you do gradient-domain sketches (like the teaser image to the right).

This work appeared as a paper at SIGGRAPH 2008. The paper and video are available on the Project Page.

Comparing the Single-FFT Direct Poisson Solve to Modern Methods (2007)

my basement

In my background research for Real-time Gradient Domain Painting, I came across a method (described by R.W. Hockney in 1965) for solving Poisson's equation by using FFTs along one dimension in conjunction with the tridiagonal matrix equation. As this method is well-suited to out-of-core use on large images, I compared it with two state-of-the-art methods from 2007 and 2008.

This work appeared as a poster at SIGGRAPH 2008. The abstract which appeared in the poster proceedings is here. The actual poster is here (note: this is a big image).

Transition Evaluation (2006-2007)

With Lei Li, Christos Faloutsos
stitchings

In this project, we investigated what makes a pleasing transition between motion capture clips. We arrived at a dynamics-based approach which works by effort minimization that not only gives any potential stitching a score, but also is able to both pick both a transition path and duration.

The results of this work appeared as a Eurographics 2008 short paper Laziness is a virtue: Motion stitching with effort minimization, which I presented.

Compiling for Graphics (2007)

With Tom Cauchois, Ronit Slyper
high detailmed-high detail
med-low detaillow detail

In this compilers class project, we investigated the potential for compiler-based level-of-detail in shaders. Our final compiler can load and parse ARB_fragment_program and ARB_vertex_program shaders into a graph-based intermediate representation, and then intelligently select per-fragment operations to hoist into the vertex shader using estimates of final visual error caused by result interpolation.

This approach should allows a single shader source to be used over many different graphics cards, as it can be dynamically degraded as performance decreases.

We think this is an interesting avenue of research, but do not intend to extend or publish these results at this time.

Motion Database Visualization (2007)

With Ronit Slyper
simple layout

In this project, we investigated methods of visualizing large data sets (like the cmu mocap database and the millions of images other lab members have crawled from flickr). We created software to automatically extract a real-time zoomable map of the data, useful for exploration and intuition-building.

We presented a preliminary poster at SCA 2007; however, these results have not yet been published further, due to other projects taking much of our time.

Motion Graphs (2006-2007)

controlled character

I investigated approaches to make motion graphs with more immediate control, as would be useful in a game environment. I settled on reinforcement learning (specifically value iteration) as the key method.

This work appeared at SIGGRAPH 2007 as Responsive characters from motion fragments. The final pdf and video are available on the project page.

Retiming (2005-2006)

With Siddhartha S. Srinivasa
retiming graph

I investigated changing the timing of motion capture data using optimization of a physically-based objective function.

This work appeared as Physics-based motion retiming at SCA 2006. The final paper is available here. Some associated video material is available here.

Additionally, I've made the messy source code available. (It's messy because I used C++ tricks to calculate inverse dynamics parametrically -- never underestimate the power of operator overloading!)

Software

ASF/AMC Viewer

amc viewer

As part of my doings, I've had to work extensively with motion capture data in ASF/AMC format (from the mocap database, in fact).

This is a release of the source code I use to read the files, wrapped up in a demo program which allows viewing. The program uses SDL+OpenGL for output.

Presentation Software

presentation hack

I use custom presentation software for my talks. The source is here to satisfy the curious. This source is provided freely. Don't sell it (not that anyone would buy it). This was never intended to be user-friendly; keep that in mind, but feel free to e-mail comments and suggestions anyway. Heck, I may even provide limited techical support if I'm not busy, so it doesn't hurt to try.

You can grab the source and some example presentations on github.

Once you've built the source (you'll need standard perforce jam -- ftjam will work, boost jam won't), simply type './hack README.hack' in the dist directory.

For equations to work you'll need latex or a different 'dist/equations/*.pl'.

If you have problems with missing opengl extensions, edit the Jamfile to get rid of modules you aren't using.

Teaching

Computer Game Programming (Fall09)

I was the instructor for Computer Game Programming. It's been a crazy ride, but playing all the games has been interesting.

Computational Photography (Fall07)

I was the TA for Computational Photography in fall 07. The students in this class did some great final projects, so -- as you've pretty much run out of my page at this point -- why not head over there and check them out?

Animation Art And Technology (Spring06)

I was the TA for AA&T in spring 2006.

Notes on setting up the linux computers for good maya menus availible here: on the course web page

Additional info about setting up the gnome window manager here

A simple example shader (draws hexagons) here.

Gentoo

Notes on using Gentoo linux instead of the SCS-supplied Fedora here. Includes notes on printing, backups, afs, and graphics group {NIS,NFS}.

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