Improved mapping functions for atmospheric refraction correction in SLR

[1] We present two new mapping functions (MFs) to model the elevation angle dependence of the atmospheric delay for satellite laser ranging (SLR) data analysis. The new MFs were derived from ray tracing through a set of data from 180 radiosonde stations globally distributed, for the year 1999, and are valid for elevation angles above 3degrees. When compared against ray tracing of two independent years of radiosonde data (1997-1998) for the same set of stations, our MFs reveal submillimetre accuracy for elevation angles above 10degrees, representing a significant improvement over other MFs, and is confirmed in improved solutions of LAGEOS and LAGEOS 2 data analysis.info:eu-repo/semantics/publishedVersio

Explorations in Distributed Ray Tracing and Photometry of Large Scenes

This work encapsulates three explorations into different implementations of distributed ray tracing, that is to say, ray tracing that has been distributed across multiple machines. Our goals lie in the rendering of scenes with more geometry than can fit within the memory of a single computer, so we focus on the distribution of memory. Ultimately, this work discusses a Spark standard (or classical) distributed ray tracer, a Spark photometric distributed ray tracer, and a single-machine Akka Typed photometric ray tracer with some basis for future distribution. Individual timing results for each ray tracer are included, but they cannot be compared due to differences in their generation. Qualitative comparisons between the ray tracers and their approaches are made, and recommendations are given to future researchers in this niche

Memory-savvy distributed interactive ray tracing

Journal ArticleInteractive ray tracing in a cluster environment requires paying close attention to the constraints of a loosely coupled distributed system. To render large scenes interactively, memory limits and network latency must be addressed efficiently. In this paper, we improve previous systems by moving to a page-based distributed shared memory layer, resulting in faster and easier access to a shared memory space. The technique is designed to take advantage of the large virtual memory space provided by 64-bit machines. We also examine task reuse through decentralized load balancing and primitive reorganization to complement the shared memory system. These techniques improve memory coherence and are valuable when physical memory is limited. C-SAF

Distributed Ray Tracing

Práce se zabývá studiem globální zobrazovací metody distribuované sledování paprsku. Ta z matematického popisu scény generuje dvourozměrné obrazy o vysoké kvalitě a realističnosti. Práce rozebírá problematiku a vysvětluje postupy řešení s touto technikou spojené. Popisuje také neoddělitelnou součást této metody a to klasické sledování paprsku.This project describes method for global display of distributed ray tracing. The method generates high quality and realistic two-dimensional images from mathematical specification of scene. The methods for solution of this issue are presented and analyzed. Integral part of this method - conventional ray tracing - is also presented.

Distributed Ray Tracing

VYSOKÉ UČENÍ TECHNICKÉ V BRNĚ Tato práce se zabývá realistickým zobrazováním počítačových scén a to metodou Distributed Ray Tracing. Tato metoda jako první řešila plošná světla, měkké stíny, hloubku ostrosti a rozmazání scény pohybem.VYSOKÉ UČENÍ TECHNICKÉ V BRNĚ Distributed Ray Tracing, also called distribution ray tracing and stochastic ray tracing, is a refinement of ray tracing that allows for the rendering of "soft" phenomena, area light, depth of field and motion blur.

DART-RAY: a 3D ray-tracing radiative transfer code for calculating the propagation of light in dusty galaxies

We present DART-Ray, a new ray-tracing 3D dust radiative transfer (RT) code designed specifically to calculate radiation field energy density (RFED) distributions within dusty galaxy models with arbitrary geometries. In this paper, we introduce the basic algorithm implemented in . DART-Ray which is based on a pre-calculation of a lower limit for the RFED distribution. This pre-calculation allows us to estimate the extent of regions around the radiation sources within which these sources contribute significantly to the RFED. In this way, ray-tracing calculations can be restricted to take place only within these regions, thus substantially reducing the computational time compared to a complete ray-tracing RT calculation. Anisotropic scattering is included in the code and handled in a similar fashion. Furthermore, the code utilizes a Cartesian adaptive spatial grid and an iterative method has been implemented to optimize the angular densities of the rays originated from each emitting cell. In order to verify the accuracy of the RT calculations performed by DART-Ray, we present results of comparisons with solutions obtained using the dusty 1D RT code for a dust shell illuminated by a central point source and existing 2D RT calculations of disc galaxies with diffusely distributed stellar emission and dust opacity. Finally, we show the application of the code on a spiral galaxy model with logarithmic spiral arms in order to measure the effect of the spiral pattern on the attenuation and RFED. © 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society

Distributed interactive ray tracing for large volume visualization

Journal ArticleWe have constructed a distributed parallel ray tracing system that interactively produces isosurface renderings from large data sets on a cluster of commodity PCs. The program was derived from the SCI Institute's interactive ray tracer (*-Ray), which utilizes small to large shared memory platforms, such as the SGI Origin series, to interact with very large-scale data sets. Making this approach work efficiently on a cluster requires attention to numerous system-level issues, especially when rendering data sets larger than the address space of each cluster node

Optical analysis of parabolic dish concentrators for solar dynamic power systems in space

An optical analysis of a parabolic solar collection system operating in Earth orbit was performed using ray tracing techniques. The analysis included the effects of: (1) solar limb darkening, (2) parametric variation of mirror surface error, (3) parametric variation of mirror rim angle, and (4) parametric variation of alignment and pointing error. This ray tracing technique used numerical integration to combine the effects of rays emanating from different parts of the sun at different intensities with the effects of normally distributed mirror-surface errors to compute the angular intensity distribution of rays leaving the mirror surface. A second numerical integration was then performed over the surface of the parabolic mirror to compute the radial distribution of brightness at the mirror focus. Major results of the analysis included: (1) solar energy can be collected at high temperatures with high efficiency, (2) higher absorber temperatures can be achieved at lower efficiencies, or higher efficiencies can be achieved at lower temperatures, and (3) collection efficiency is near its maximum level across a broad plateau of rim angles from 40 deg to 70 deg