Sumanta Pattanaik

University of Central Florida, Orlando, Florida, United States

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Publications (102)41.67 Total impact

  • Charly Collin · Sumanta Pattanaik · Patrick LiKamWa · Kadi Bouatouch
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    ABSTRACT: Interest in polarization properties of rendered materials is growing, but so far discussions on polarization have been restricted only to surface reflection, and the reflection due to subsurface scattering is assumed to be unpolarized. Findings from other fields (e.g. optics and atmospheric science) show that volumetric interaction of light can contribute to polarization. We thus investigated the polarized nature of the radiance field due to subsurface scattering as a function of the thickness of the material layer for various types of materials. Though our computations show negligible polarization for material layers of high thickness, light reflected on thin layered materials show significant degrees of polarization. Consequently, polarization cannot be ignored for subsurface component of reflection from painted surfaces (particularly painted metal surfaces) or from coated materials. Reflection from such surfaces is computed by solving for light transport in the different paint layers. In this paper we employ the vector radiative transfer equation (VRTE), which is the polarized version of the radiative transfer equation, inside the material. We use and detail a discrete ordinate based method to solve the VRTE and use the solution to compute the polarized radiance field at the surface of the material layer. We generate the polarimetric BRDF from the solutions of the VRTE for incident irradiance with different polarizations. We validate our VRTE solution against a benchmark and demonstrate our results through renderings using the computed BRDF.
    No preview · Article · Dec 2014 · Computers & Graphics
  • Eugene M. Taranta · Sumanta N. Pattanaik
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    ABSTRACT: Uniform grids are a spatial subdivision acceleration structure well suited for ray tracing. They are known for their fast build times and ease of use, but suffer from slow traversals in the presence of empty space. To address this issue, we present macro 64-regions, a new GPU based approach for finding and storing empty volumes in an underlying uniform grid. This allows for fast traversals through regions that do not contain scene geometry. Further, unlike previous solutions to this problem, we do not store a hierarchical structure and therefore the traversal steps are simplified. Because macro 64-regions are dependent on an underlying grid, we also introduce an improvement in the grid construction process. Our method does not rely on sorting as previous methods do, but instead uses atomic operators to manage bookkeeping during the build. Using our proposed methods, we show a substantial improvement in build time, trace time, as well as an improvement in the consistency of rendering times for randomly generated views.
    No preview · Article · Jun 2014 · The Visual Computer
  • Charly Collin · Sumanta Pattanaik · Patrick LiKamWa · Kadi Bouatouch
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    ABSTRACT: Interest in polarization properties of the rendered materials is growing, but so far discussions on polarization have been restricted only to surface reflection, and the reflection due to subsurface scattering is assumed to be unpolarized. Findings from other field (e.g. optics and atmospheric science) show that volumetric interaction of light can contribute to polarization. So we investigated the polarized nature of the radiance field due to subsurface scattering as a function of the thickness of the material layer for various types of materials. Though our computations shows negligible polarization for material layers of high thickness, thin layered materials show significant degree of polarization. That means polarization cannot be ignored for subsurface component of reflection from painted surfaces (particularly painted metal surfaces) or from coated materials. In this paper we employ the vector radiative transfer equation (VRTE), which is the polarized version of the radiative transfer equation inside the material. We use a discrete ordinate based method to solve the VRTE and compute the polarized radiance field at the surface of the material layer. We generate the polarimetric BRDF from the solutions of the VRTE for incident irradiance with different polarizations. We validate our VRTE solution against a benchmark and demonstrate our results through renderings using the computed BRDF.
    No preview · Article · Jan 2014 · Proceedings - Graphics Interface
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    ABSTRACT: In this paper, we present a novel approach to progressive photon-based volume rendering techniques. By making use of two Kd-trees (built in a preprocessing step) to store view beams (primary rays intersecting the medium) and visible points, our method allows to handle scenes with specular and refractive objects as well as homogeneous and heterogeneous participating media and does not require the storage of photon maps, which solves the memory management issue. These data structures are used to drive the photon shooting process by considering the photon visibility as an importance function (similarly to Hachisuka and Jensen in ACM Trans. Graph. 30(5):114:1–114:11, 2011) for scenes containing participating media. Finally, we demonstrate that our method can be easily combined with the most recent particle tracing approaches such as the one presented in Jarosz et al. (ACM Trans. Graph., vol. 30(6), 2011).
    No preview · Article · Sep 2013 · The Visual Computer
  • Charly Collin · Ke Chen · Ajit Hakke-Patil · Sumanta Pattanaik · Kadi Bouatouch
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    ABSTRACT: This paper presents an accurate method to compute the bidirectional reflectance distribution function (BRDF) due to subsurface scattering inside the material of the objects. This computation requires iterating over the different lighting directions, and solving the integro-differential equation of light transport (scattering and absorption). Solving the light transport equation is expensive, and solving it independently for different directions adds even further to the expense. However most of the computations are very similar between directions. We make use of Green's function of the transport problem to have a better separation between computations that are independent of incident directions from those that are dependent. This allows us to avoid as much repetition in the computations as possible, thus gives us a faster BRDF computation method without any loss of accuracy. We validate our method against a standard light transport solver and use it to compute BRDF for a variety of materials.
    No preview · Article · May 2013
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    ABSTRACT: We present a novel technique for physically based rendering of participating media like cloud, smoke, wax, marble, etc. We solve the radiative transfer equation (RTE) for participating media using the Modified Discrete Ordinate Method (MDOM), which computes the final solution as a combination of a direct and an indirect component. We propose a scalable GPU based parallel pipeline, for solving the RTE using the MDOM. This parallel RTE solver is capable of rendering intermediate results such as single scattering approximation. We overcome GPU memory size limitations by using low resolution radiance storage while doing high resolution radiance propagation. Furthermore, we achieve scalability by implementing an efficient volumetric data streaming mechanism. Our results demonstrate the ability of our method to render high quality multiple scattering effects.
    No preview · Article · May 2013
  • Ke Chen · Charly Collin · Ajit Hakke-Patil · Sumanta Pattanaik
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    ABSTRACT: Accurately modeling BRDF for real world materials is important and challenging for realistic image synthesis. For a majority of materials most of the incident light enters the material, undergoes multiple scattering under the surface before exiting the material's surface as reflection. Physically correct modeling of such BRDF must take into account of this subsurface volumetric light transport. Most of the accurate numerical solution methods (ex: Monte Carlo, Discrete Ordinate Methods (DOM)) for volumetric light transport compute radiance field for the whole volume, and are expensive. As BRDF ultimately relates only the outgoing radiation field at the boundary to the incident radiation, radiation field computed for the bulk of the material does not provide any useful information and hence the effort involved in computing them can be considered as wasteful. So for efficient BRDF computation any method that allows us to compute the radiance field only at the boundary would be a preferable choice. The search for such a method led us to the Ambartsumian's method [Sobolev 1975; Mishchenko et al. 1999].
    No preview · Conference Paper · Mar 2013
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    ABSTRACT: A new method for interactive rendering of complex lighting effects combines two algorithms. The first performs accurate ray tracing in heterogeneous refractive media to compute high-frequency phenomena. The second applies lattice-Boltzmann lighting to account for low-frequency multiple-scattering effects. The two algorithms execute in parallel on modern graphics hardware. This article includes a video animation of the authors' real-time algorithm rendering a variety of scenes.
    No preview · Article · Mar 2012 · IEEE Computer Graphics and Applications
  • Source
    Adrien Gruson · A Hakke Patil · Rémi Cozot · Kadi Bouatouch · Sumanta Pattanaik
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    ABSTRACT: Light going through a participating medium like smoke can be scattered or absorbed by every point in the medium. To accurately render such a medium we must compute the radiance resulting at every point inside the medium because of these physical effects, which have been modeled by the radiative transfer equation. Computing the radiance at any point inside a participating medium amounts to numerically solving this radiative transport equa-tion. Discrete Ordinate Method (DOM) is a widely used solution method. DOM is computationally intensive. Fattal [Fat09] proposed Light Propagation Maps (LPM) to expedite DOM computation. In this paper we propose a streaming based parallelization of LPM to run on SIMD graphics hardware. Our method is fast and scalable. We report more than 20× speed improvement by using our method as compared to Fattal's original method. Using our approach we are able to render 64 × 64 × 64 dynamic volumes with multiple scattering of light at interactive speed on complex lighting, and are able to render volumes of any size independent of the GPU memory capability.
    Full-text · Article · Jan 2012
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    ABSTRACT: In this paper we propose a novel technique to perform real-time rendering of translucent inhomogeneous materials, one of the most well-known problems of computer graphics. The developed technique is based on an adaptive volumetric point sampling, done in a preprocessing stage, which associates to each sample the optical depth for a predefined set of directions. This information is then used by a rendering algorithm that combines the object’s surface rasterization with a ray tracing algorithm, implemented on the graphics processor, to compose the final image. This approach allows us to simulate light scattering phenomena for inhomogeneous isotropic materials in real time with an arbitrary number of light sources. We tested our algorithm by comparing the produced images with the result of ray tracing and showed that the technique is effective. KeywordsRendering-Subsurface scattering-GPU computing
    Full-text · Article · Jun 2010 · The Visual Computer
  • Juraj Obert · Fabio Pellacini · Sumanta N. Pattanaik
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    ABSTRACT: We present an approach for editing shadows in all-frequency lighting environments. To support artistic control, we propose to decouple shadowing from lighting and focus on providing intuitive controls to edit the former. To accomplish this task, we precompute and store scene visibility information separately from lighting and BRDFs and allow artists to edit visibility directly, by providing operations to select shadows and edit their shape. To facilitate a wider range of editing operations, we generalize visibility from binary to three-channel floating point quantities and introduce a novel shadow representation based on computation of visibility ratios between the original render and the edited one. We demonstrate our results for diffuse and glossy surfaces, still scenes and animations.
    No preview · Article · Jun 2010 · Computer Graphics Forum
  • Erik Reinhard · Greg Ward · Sumanta N. Pattanaik · Paul E. Debevec · Wolfgang Heidrich

    No preview · Book · Jan 2010
  • Kevin Boulanger · Kadi Bouatouch · Sumanta N. Pattanaik

    No preview · Article · Jan 2010
  • Source
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    ABSTRACT: Abstract In the last few years, researchers in the field of High Dynamic Range (HDR) Imaging have focused on providing tools for expanding Low Dynamic Range (LDR) content for the generation of HDR images due to the growing popularity of HDR in applications, such as photography and rendering via Image-Based Lighting, and the imminent arrival of HDR displays to the consumer market. LDR content expansion is required due to the lack of fast and reliable consumer level HDR capture for still images and videos. Furthermore, LDR content expansion, will allow the re-use of legacy LDR stills, videos and LDR applications created, over the last century and more, to be widely available. The use of certain LDR expansion methods, those that are based on the inversion of Tone Mapping Operators (TMOs), has made it possible to create novel compression algorithms that tackle the problem of the size of HDR content storage, which remains one of the major obstacles to be overcome for the adoption of HDR. These methods are used in conjunction with traditional LDR compression methods and can evolve accordingly. The goal of this report is to provide a comprehensive overview on HDR Imaging, and an in depth review on these emerging topics.
    Full-text · Article · Dec 2009 · Computer Graphics Forum
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    Adrià Forés · Sumanta N. Pattanaik · Carles Bosch · Xavier Pueyo
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    ABSTRACT: This paper introduces a novel system for interactive modeling and designing of arbitrary BRDFs. The system is able to deal with BRDFs defined in a variety of forms, such as analytical models, measured data or data obtained by simulation. The system also allows designing BRDFs from scratch using a combination of different analytical lobes. Using the programmable graphics hardware, it then performs interactive display of the designed BRDF, and its rendering on objects lit by complex illumination. The system also allows the fitting of an input BRDF defined in any form to our analytical lobe combination, so that it can be efficiently evaluated with GPU based rendering. The idea behind this work is to make available a general system for designing, fitting and rendering BRDFs, that is intuitive and interactive in nature. We plan to use this as a tool for simulation and modeling of complex physically-based BRDFs, and thus provide access to a larger variety of material models to the rendering community.
    Preview · Conference Paper · Sep 2009
  • Kévin Boulanger · Sumanta N Pattanaik · Kadi Bouatouch
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    ABSTRACT: The authors present a real-time grass rendering technique that works for large, arbitrary terrains with dynamic lighting, shadows, and a good parallax effect. A novel combination of geometry and lit volume slices provides accurate, per-pixel lighting. A fast grass-density management scheme allows the rendering of arbitrarily shaped patches of grass.
    No preview · Article · Mar 2009 · IEEE Computer Graphics and Applications
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    Musawir A Shah · Jaakko Konttinen · Sumanta Pattanaik
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    ABSTRACT: The authors present an algorithm for real-time realistic rendering of translucent materials such as marble, wax, and milk. Their method captures subsurface scattering effects while maintaining interactive frame rates. The main idea of this work is that it employs the dipole diffusion model with a splatting approach to evaluate the integral over the surface area for computing illumination due to multiple scattering.
    Full-text · Article · Mar 2009 · IEEE Computer Graphics and Applications
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    ABSTRACT: Smell is a key human sense which can significantly effect our perception of an environment. Although, typically not as developed as our other senses, the presence of a pleasant or unpleasant smell can alter the way we view a scene. Such a cross-modal effect can be substantial with parts of a scene literally going unnoticed as the smell dominates our senses. This paper investigates the cross-modal affect on the perception of the real-time animation of a field of grass in the presence of the smell of cut-grass. Rendering the high level of detail of a close-up view of a field of grass is computationally very demanding. In the real world the smell of grass would be present, and especially strong if the grass had just been cut, for example in preparation for a sports event. By exploiting the cross-modal interaction between smell and visuals we are able to render a lower quality version of a field of grass at a reduced computational cost, without the viewer being aware of the quality difference compared to a high quality version.
    No preview · Article · Jan 2009
  • Kévin Boulanger · Kadi Bouatouch · Sumanta Pattanaik
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    ABSTRACT: High quality lighting is one of the challenges for interactive tree rendering. To this end, this paper presents a lighting model allowing real-time rendering of trees with convincing indirect lighting. Rather than defining an empirical model to mimic lighting of real trees, we work at a lower level by modeling the spatial distribution of leaves and by assigning them probabilistic properties. We focus mainly on precise low-frequency lighting that our eyes are more sensitive to and we add high-frequency details afterwards. The resulting model is efficient and simple to implement on a GPU.
    No preview · Article · Sep 2008 · Computer Graphics Forum
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    ABSTRACT: New gradients Gradients by [Křivánek et al. 2005] Figure 1: Right: The gradient computation proposed by [Křivánek et al. 2005] does not properly handle significant change of occlusion in the sampled environment and leaves visible interpolation artifacts. Left: The radiance gradient computation proposed in this paper handles occlusion changes and leads to a smoother indirect illumination interpolation on the glossy floor. The two images in the middle are cut out from the two images on the very left and very right. Abstract We describe a new and accurate algorithm for computing transla-tional gradients of incoming radiance in the context of a ray tracing-based global illumination solution. The gradient characterizes how the incoming directional radiance function changes with displace-ment on a surface. We use the gradient for a smoother radiance interpolation over glossy surfaces in the framework of the radi-ance caching algorithm. The proposed algorithm generalizes the irradiance gradient computation by [Ward and Heckbert 1992] to allow its use for non-diffuse, glossy, surfaces. Compared to previ-ous method for radiance gradient computation, the new algorithm yields better gradient estimates in the presence of significant oc-clusion changes in the sampled environment, allowing a smoother indirect illumination interpolation.
    Full-text · Article · Aug 2008

Publication Stats

3k Citations
41.67 Total Impact Points

Institutions

  • 2002-2014
    • University of Central Florida
      • Department of Electrical Engineering & Computer Science
      Orlando, Florida, United States
  • 2006
    • National Institute for Research in Computer Science and Control
      Le Chesney, Île-de-France, France
  • 1996-2000
    • Cornell University
      • Department of Computer Science
      Итак, New York, United States
    • IRISA - Institut de Recherche en Informatique et Systèmes Aléatoires
      Roazhon, Brittany, France