Geometric and arithmetic culling methods for entire ray packets

technical reportRecent interactive ray tracing performance has been mainly derived from the use of ray packets. Larger ray packets allow for significant amortization of both computations and memory accesses; however, the majority of primitives are still intersected by each ray in a packet. This paper discusses several methods to cull entire ray packets against common primitives (box, triangle, and sphere) that allows an arbitrary number of rays to be tested by a single test. This provides cheap ?all miss? or ?all hit? tests and may substantially improve the performance of an interactive ray tracer. The paper surveys current methods, provides details on three particular approaches using interval arithmetic, bounding planes, and corner rays, describes how the respective bounding primitives can be easily and efficiently constructed, and points out the relation among the different fundamental concepts

Evaluating Educational Interventions in Emergency Medicine

This article presents the proceedings of the 2012 Academic Emergency Medicine consensus conference breakout group charged with identifying areas necessary for future research regarding effectiveness of educational interventions for teaching emergency medicine ( EM ) knowledge, skills, and attitudes outside of the clinical setting. The objective was to summarize both medical and nonmedical education literature and report the consensus formation methods and results. The authors present final statements to guide future research aimed at evaluating the best methods for understanding and developing successful EM curricula using all types of educational interventions.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94811/1/acem12022.pd

Packet-based whitted and distribution ray tracing

technical reportMuch progress has been made toward interactive ray tracing, but most research has focused specifically on ray casting. A common approach is to use ?packets? of rays to amortize cost across sets of rays. Little is known about how well packet-based techniques will work for reflection and refraction rays, which do not share common origins, and often have less directional coherence than viewing and shadow rays. Since the primary advantage of ray tracing over rasterization is the computation of global effects, such as accurate reflection and refraction, this lack of knowledge should be corrected. Our ultimate goal is to achieve interactive distribution ray tracing with randomized rays for glossy reflections, soft shadows, motion blur and depth of field. But it is not clear that the randomization would not further erode the effectiveness of techniques used to accelerate ray casting. This paper addresses the question of whether packet-based ray algorithms can be effectively used for more than visibility computation. It is shown that with the appropriate choice of data structure and packet assembly algorithm, useful algorithms for ray casting do indeed extend to both Whitted-style and distribution ray tracing programs