Research Page

For a list of my publications, please visit my publications page.

Research Interests

Physics-based Computer Graphics and Vision, Computational Photography, Optics and Sensors.

Research Projects (click on images for detailed project pages)

	Underwater Imaging: Seeing Clearer and Farther in Poor Visibility [CVPR 2008] In this work, we design active lighting and sensing systems for controlling light transport in the presence of participating media, and obtain higher quality data even in poor visibility conditions. First, we present a technique of polarized light striping based on combining polarization imaging and structured light striping. We show that this technique out-performs different existing illumination and sensing methodologies. Second, we present a numerical approach for computing the optimal relative sensor-source position, which results in the best quality image. For details, please click here.
	Fast Simulation and Rendering of Participating Media [SCA 07] In this paper, we present a unified framework for reduced space modeling and rendering of dynamic and non-homogenous participating media, like snow, smoke, dust and fog. Our technique achieves computational speed-ups of one to three orders of magnitude as compared to the traditional spatial domain methods, while having low memory and pre-computation requirements. We demonstrate many interesting visual effects resulting from particles immersed in fluids as well as volumetric scattering in non-homogenous and dynamic participating media, such as fog and mist. For details, please click here.
	Measuring Scattering Properties of Participating Media [SIGGRAPH 06] In this paper, we have developed a simple device and technique for robustly estimating the scattering parameters of a broad class of participating media such as juices, beverages, paints, sugar/salt crystals and suspended impurities. The key idea is to dilute the concentrations of the media so that single scattering effects dominate and multiple scattering becomes negligible, leading to a simple and robust algorithm for estimating the scattering parameters. We have measured the scattering parameters of 40 commonly found materials that can be immediately used for rendering. We can also create realistic images of mixtures of the original measured materials, thus giving the user significant flexibility in creating realistic images of participating media. For details, please click here.
	High Resolution Tracking of Facial Expressions Using Harmonic Maps [ICCV 05] In this paper, we present a novel fully automatic method for high resolution, non-rigid dense 3D point tracking. The novelty of this paper is the development of an algorithmic framework for 3D tracking that unifies tracking of intensity and geometric features using harmonic maps. While the previous uses of harmonic maps provided only global alignment, the proposed introduction of interior feature constraints guarantees that non-rigid deformations will be accurately tracked as well. For details, please click here.
	Modeling and Rendering of Architectural Scenes [Eurographics 2003] In this paper, we present a novel approach for multilevel modelling and rendering of architectural scenes using a small set of photographs. Our approach is based on interactive probing of intuitive measures like lengths, widths and heights from single view metrology. These measures can then be aggregated with additional input if need be, for defining high-level primitives such as planes, prismatic blocks, cuboids, spheres, and general surfaces of translation and revolution. Our approach is computationally simple, fast and robust. We demonstrate our results by building a model of a magnificent historical monument in Delhi – Humayun’s tomb. For details, please click here.
	Interactive Image Segmentation Toolbox Lazy Snapping and GrabCut are 2D image segmentation tools based on the interactive graph-cuts technique proposed by Boykov and Jolly. Lazy Snapping requires the user to specify foreground and background seeds, and performs 2D segmentation with the seeds as hard constraints. GrabCut makes the process more automatic by using iterated graph cuts – the only user interaction required is a bounding box of the foreground object. We provide an implementation of both these tools, along with a third tool which combines both these methods. Our code uses the maxflow code by Vladimimr Kolmogorov. For details, please click here.