Jerry Tessendorf

Clemson University | CU · School of Computing

Many research areas require simulating particle transport through scattering media. For instance, radiative transfer is useful for computer graphics and for neutron transport in nuclear physics. These transport simulations tend to be computationally expensive for problems involving large amounts of multiple scattering in generic geometries, requiri...

This paper proposes a real-time approach to animate a character walking in different environments for a video game setting. The technique combines a physics-based model with procedural animation and motion editing. Highlighting environmental interaction in fluids, the paper leverages simplified drag forces to drive realistic changes from existing l...

A method of solving the radiative transfer equation using Feynman path integrals (FPIs) is discussed. The FPI approachis a mathematical framework for computing multiple scattering in participating media. Its numerical behavior is not well known, and techniques are being developed to solve the FPI approachnumerically. A missing numerical technique i...

A Monte Carlo multiple scattering technique for participating media is extended. Validation against an experimentally well-studied optics problem is discussed. Designing initial paths for a numerical integration of Feynman path integrals is posed. A plot of the resulting integration is discussed.

This note addresses the subject of advection around the theme of applying Characteristic Maps as a method of constructing solvers.

This panel will discuss and assess how academia and industry can articulate their visions and develop a cohesive understanding of each others roles and responsibilities in the hopes of revealing mutually beneficial protocols and guidelines to elevate both academia and industry.

We propose a method of increasing the apparent spatial resolution of an existing liquid simulation. Previous approaches to this “up-resing” problem have focused on increasing the turbulence of the underlying velocity field. Motivated by measurements in the free surface turbulence literature, we observe that past certain frequencies, it is sufficien...

The propagation kernel for time dependent radiative transfer is represented by a Feynman path integral (FPI). The FPI is approximately evaluated in the spatial-Fourier domain. Spatial diffusion is exhibited in the kernel when the approximations lead to a Gaussian dependence on the Fourier domain wave vector. The approximations provide an explicit e...

A model for real-time generation of deep-water waves is suggested. It is based on a lattice-Boltzmann (LB) technique. Computation of wave dynamics and (ray-traced) rendering for a lattice of size 10242 can be carried out simultaneously on a single graphics card at 25 frames per second. In addition to the computational speed, the LB technique is see...

Fluid simulations based on the Incompressible Navier-Stokes equations are commonplace computer graphics tools in the visual effects industry. These simulations mostly come from custom C++ code written by the visual effects companies. Their significant impact in films was recognized in 2008 with Academy Awards to four visual effects companies for th...

One of the action sequences in the film The A-Team takes place within a growing system of storm clouds. The story plot required the creation of a fully D environment of clouds covering tens of kilometers of evolving storm, modeled and simulated at high resolution because the camera and story elements are embedded within it. The cloud system covered...

We synchronize cameras and analog lighting with high speed projectors. Radiometric compensation allows displaying flexible blue screens on arbitrary real world surfaces. A fast temporal multiplexing of coded projection and flash illumination enables ...

Over the last couple of years, Rhythm and Hues Studios developed various fluid simulations techniques, which can be combined in a flexible process to maximize the ability to manipulate and art direct each step. This workflow was successfully developed and applied on recent feature work such as "Superman Returns" and "Happy Feet".

This updated course on simulating natural phenomena will cover the latest research and production techniques for simulating most of the elements of nature. The presenters will provide movie production, interactive simulation, and research perspectives on the difficult task of photorealistic modeling, rendering, and animation of natural phenomena. T...

Rendering of atmospheric bodies involves modeling the complex interaction of light throughout the highly scattering medium of water and air particles. Scattering by these particles creates many well-known atmospheric optical phenomena including rainbows, halos, the corona, and the glory. Unfortunately, most radiative transport approximations in com...

Rendering of atmospheric bodies involves modeling the complex interaction of light throughout the highly scat- tering medium of water and air particles. Scattering by these particles creates many well-known atmospheric optical phenomena including rainbows, halos, the corona, and the glory. Unfortunately, most radiative transport approximations in c...

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The 3D volumetric character of clouds is a critically important factor in determining cloud structure as seen in infrared imagery. Using a longwave cloud scene simulator which images a 3D cloud volume, the 3D structure has been shown to be particularly important when viewing at low grazing angles. In order to conduct analyses of cloud scene structu...

Sets of image data from the MUSIC (Multi Spectral Infrared Camera) have been analyzed to obtain the spatial and temporal structure of cirrus and stratus cloud scenes at small spatial and temporal scales. The MUSIC data were collected in 1989 in a side-looking airborne geometry. The large clutter to noise ratios found in this analysis for both cirru...

Temporal pulse stretching is a consequence of the multiple scatter by ocean water of a laser pulse. Although the physical process behind pulse stretching is intuitively clear, there is no widely held quantitative definition of it. Here temporal pulse stretching is defined in terms of temporal moments of the radiance at a fixed position and orientat...

Longwave infrared imagery of cloud fields are examined in terms of their power spectral density (PSD). In order to systematically investigate the dependence of the PSD on viewing conditions, a cloud scene simulator is employed to generate images of a simulated cloud field. The cloud field is fully three dimensional and is describes by its fluctuati...

Longwave infrared imagery of cloud fields are examined in terms of their power spectral density (PSD). In order to systematically investigate the dependence of the PSD on viewing conditions, a cloud scene simulator is employed to generate images of a simulated cloud field. The cloud field is fully three dimensional and is describes by its fluctuati...

An analytical expression for the underwater radiance distribution due to a purely `delta function' sun is discussed. The expression derives from a WKB evaluation of the path integral solution for time-dependent radiative transfer, integrated over long times, and does not involve a small-angle approximation. However, a diffusion-limiting length scal...

Mean and rrns fluctuations of downwelling solar irradiance below a rough ocean surface have been modelled using the small-angle approximation for the in-water radiance distribution. For comparison, a ray-trace approach has also been used to calculate the fluctuation statistics in the limit of no scattering. The mean irradiance decays rapidly nea...

After a review of appropriate concepts in local surface geometry, a formally exact solution of the radiative transfer equation is constructed, for transfer from one surface of arbitrary shape to another. The solution is obtained from repeated application of the linear interaction principle to form a path integral over paths that cross many intermed...

The time-dependent radiative transfer equation in an absorbing and scattering medium is recast as an evolution equation that is similar to the global formulation of Preisendorfer. All the properties of radiative transfer are embodied in the evolution operator, which can be studied and manipulated in the Dirac operator notation. The reciprocity theo...

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Qualitative and quantitative properties of the in-water distribution of solar radiance, as predicted by the radiative transfer equation, are examined. Two solutions of the radiative transfer equation in the small-angle limit are presented. One of the solutions is the well-known traditional small-angle solution (designated SA). The other (designated...

The effects of absorption and scattering on the propagation of a finite-size laser pulse through ocean water are investigated theoretically, applying a finite-difference model based on the time-dependent radiative-transfer equation. The derivation of the finite-difference evolution algorithm is outlined; its FORTRAN numerical implementation is expl...

The radiative-transfer equation describes the collection of paths taken by an element of radiation as it travels from one location to another. When backscatter can be ignored, the exact solution is constructed as a formal sum (path integral) over all such paths. In the appropriate limit the usual (diffusive) small-angle solution and the multiple-sc...

An algorithm and numerical results are presented for the causal evolution of a radiance field which satisfies the time-dependent radiative transfer equation in a scattering and absorbing medium. Propagation from point to point requires a method of spatial interpolation which does not violate causality, i.e., a method which ensures that the radiance...

Fradkin-type propagator representations are written for solutions to Navier-Stokes and related equations, for arbitrary dimension D and arbitrary source geometry. In the limit of very small viscosity, velocity/vorticity solutions are given in terms of Cauchy position coordinates q of a particle advected by the velocity flow v, using a set of couple...

A new approximation scheme is introduced to study velocity correlation functions of turbulent flow of viscous incompressible fluids. The method employs a steepest-descent approximation on the MSR formalism after the velocity field integration has been evaluated exactly. In order to carry out the steepest-descent approximation it is necessary to int...

Cinesite Digital Studios Figure 1: Cloud-like distribution with 1,167,396,675 particles, rendered using volumetric self-shadowing and the other techniques described in the text. Abstract Particles systems play a very strong role in entertainment computer graphics because of their versatility and easy connection to natural phenomena. Some applicatio...

The radiative transport problem is cast in integral form using a transport kernel. The transport kernel has an explicit representation in terms of a Feynman Path Integral over all paths between selected points in a volume. This representation is setup in detail. Numerical evaluation of this Path Integral is formulated with a Frenet-Serret based pro...

Natural volumetric media have phase functions which typically are sharply peaked in the forward scattering direction, with backscat- ter accounting for only a few percent of the total angular redistri- bution from a single scattering event. This property has been ex- ploited in the past in the small-angle approximation for radiative transfer, succe...

The Method of Characteristics is examined as a tool for making fluid simulation more efficient and effective in VFX production. A mathematical frame-work for a Characteristic Map is shown to be a general-ization of the previous methods called Gridless Advec-tion and Semi-Lagrangian Mapping. We demonstrate that the Characteristic Map can be used to...