We compute the attenuation of gamma-rays from remote quasars due to interactions with ambient low-energy photons produced by stars in galaxies and show that the next-generation gamma ray telescopes can probe the cosmic star formation rate at high redshifts.

We propose a new approach to the Casimir effect based on classical ray optics. We define and compute the contribution of classical optical paths to the Casimir force between rigid bodies. Our approach improves upon the proximity force approximation. It can be generalized easily to arbitrary geometries, different boundary conditions, to the computation of Casimir energy densities and to many oth...

We describe the simulation data produced by a pilot programme to compute mock weak gravitational lensing maps for a range of currently popular cosmological models by ray tracing through high-resolution N-body simulations. The programme required only a modest investment in computer time to produce maps accurate to arcminute scales covering hundreds of square degrees of sky for 4 cosmological mod...

We present a new and efficient method to compute the intersection point between a convex planar quadrilateral and a ray. Contrary to other methods, the bilinear coordinates of the intersection point are computed only for rays that hit the quadrilateral. Rays that do not hit the quadrilateral are rejected early. Our method is up to 40% faster compared to previous approaches.

Information derived from the superior mirage is used to compute the average vertical temperature profile in the atmosphere between the observer and a known object. The image is described by a plot of ray-elevation angle at the eye against elevation at which that ray intersects the object. The computational algorithm, based on the tracing of rays that have at most one vertex, iteratively adjusts...

We present a method for high quality soft shadows for area lights in cinematic lighting. The method is an extension of traditional shadow maps, so it has the advantage of image based shadow methods; the algorithm’s complexity is independent of geometric complexity. We introduce multilayer transparent shadow maps, which can be used to produce high quality soft shadows for scenes with extremely c...

The goal of this paper is to express simply the number of photons impinging on a target in the framework of accelerator-based Compton X-ray sources. From the basic kinematics of Compton sources, analytic formulas for the angular and the spectral fluxes are established as functions of the energy spread or/and the angular divergence of the electron and the laser beams. Their detailed predictions ...

We present the surface area traversal order (SATO) metric to accelerate shadow ray traversal. Our formulation uses the surface area of each child node to compute the TO. In this metric, we give a traversal priority to the child node with the larger surface area to quickly find occluders. Our algorithm reduces the pre-processing overhead significantly, and is much faster than other metrics. Over...

A progress report on our search for radio-quiet gamma-ray pulsars in the EGRET database is presented. The search technique utilizes signi cant computational resources of the Center for advanced Computing Research at Caltech to compute Gigapoint power spectra for some of the brighter, unidenti ed EGRET gamma-ray sources which, like Geminga, may not be visible at radio wavelengths. Two sources, G...

When working with large and complex scenes, situations arise where light flux takes complex paths to reach the observer. In such cases, traditional stochastic algorithms, like ray tracing algorithms, will have difficulties to compute noise-free images. Our present research aims to solve this problem using the 3d scene skeleton as a coarse representation. Indeed, curvilinear skeletons can be use...