Short looping videos concisely capture the dynamism of natural scenes. Creating seamless loops usually involves maximizing spatiotemporal consistency and applying Poisson blending. We take an end-to-end view of the problem and present new techniques that jointly improve loop quality while also significantly reducing processing time. A key idea is to relax the consistency constraints to anticipate the subsequent blending, thereby enabling looping of low-frequency content like moving clouds and changing illumination. We also analyze the input video to remove an undesired bias toward short loops. The quality gains are demonstrated visually and confirmed quantitatively using a new gradient-domain consistency metric. We improve system performance by classifying potentially loopable pixels, masking the 2D graph cut, pruning graph-cut labels based on dominant periods, and optimizing on a coarse grid while retaining finer detail. Together these techniques reduce computation times from tens of minutes to nearly real-time.

We exploit the falloff of acuity in the visual periphery to accelerate graphics computation by a factor of 5-6 on a desktop HD display (1920x1080). Our method tracks the user's gaze point and renders three image layers around it at progressively higher angular size but lower sampling rate. The three layers are then magnified to display resolution and smoothly composited. We develop a general and efficient antialiasing algorithm easily retrofitted into existing graphics code to minimize "twinkling" artifacts in the lower-resolution layers. A standard psychophysical model for acuity falloff assumes that minimum detectable angular size increases linearly as a function of eccentricity. Given the slope characterizing this falloff, we automatically compute layer sizes and sampling rates. The result looks like a full-resolution image but reduces the number of pixels shaded by a factor of 10-15. We performed a user study to validate these results. It identifies two levels of foveation quality: a more conservative one in which users reported foveated rendering quality as equivalent to or better than non-foveated when directly shown both, and a more aggressive one in which users were unable to correctly label as increasing or decreasing a short quality progression relative to a high-quality foveated reference. Based on this user study, we obtain a slope value for the model of 1.32-1.65 arc minutes per degree of eccentricity. This allows us to predict two future advantages of foveated rendering: (1) bigger savings with larger, sharper displays than exist currently (e.g. 100 times speedup at a field of view of 70° and resolution matching foveal acuity), and (2) a roughly linear (rather than quadratic or worse) increase in rendering cost with increasing display field of view, for planar displays at a constant sharpness.

Recent work defines vector graphics using diffusion between colored curves. We explore higher-order fairing to enable more natural interpolation and greater expressive control. Specifically, we build on thin-plate splines which provide smoothness everywhere except at user-specified tears and creases (discontinuities in value and derivative respectively). Our system lets a user sketch discontinuity curves without fixing their colors, and sprinkle color constraints at sparse interior points to obtain smooth interpolation subject to the outlines. We refine the representation with novel contour and slope curves, which anisotropically constrain interpolation derivatives. Compound curves further increase editing power by expanding a single curve into multiple offsets of various basic types (value, tear, crease, slope, and contour). The vector constraints are discretized over an image grid, and satisfied using a hierarchical solver. We demonstrate interactive authoring on a desktop CPU.

Integrating force feedback with a complete real-time virtual environment system presents problems which are more difficult than those encountered in building simpler forcefeedback systems. In particular, lengthy computations for graphics or simulation require a decoupling of the haptic servo loop from the main application loop if high-quality forces are to be produced. We present some approaches to these problems and describe our force-feedback software library which implements these techniques and provides other benefits including haptic-textured surfaces, device independence, distributed operation and easy enhancement.

The NanoManipulator system has been expanded from a virtual-reality interface for a specific scanning tunneling microscope to include control of atomic force microscopes. The current state of the system is reviewed, and new tools extending the user's feel and control in manipulation and fabrication in the mesoscopic regime are detailed. Manipulations that could not be performed using the techniques available from commercial SPM systems are demonstrated, and the direction of ongoing research is outlined.