Direct Ray tracing of smoothed and displacement mapped triangles

Journal ArticleWe present an algorithm for ray tracing displacement maps that requires no additional storage over the base model. Displacement maps are rarely used in ray tracing due to the cost associated with storing and intersecting the displaced geometry. This is unfortunate because displacement maps allow the addition of large amounts of geometric complexity into models. Our method works for models composed of triangles with normals at the vertices. In addition, we present a special purpose displacement that creates a smooth surface that interpolates the triangle vertices and normals. Thus two adjacent triangles which share two vertices and normals will be smoothly interpolated. This combination allows relatively coarse models to be displacement mapped and ray traced with much less storage and fewer artifacts due to tessellation

Visual glue

technical reportOne key function of graphics systems is to present information about the 3-D structure of modeled environments. For real-time simulations, conveying a sense of contact between touching surfaces and relative position and motion between proximate objects is particularly critical. Neither stereo nor occlusion cues are completely effective for such fine judgments. Conventional wisdom often argues that shadows play a critical role. Less often, it is argued that interreflection also contributes to the sense that two surfaces are touching. This paper explores the actual utility of shadows and interreflection in signaling contact and suggests how this information can be exploited in real-time rendering systems to glue objects to surfaces

Single sample soft shadows

Journal ArticleA simple extension to ray tracing is presented that creates visually plausible "soft" shadows with little extra computation. Although these soft shadows are approximate, they are robust and have penumbra widths that behave in a believable way, including accurate placement of singularities where penumbra width is zero. The method has continuous behavior in space and time, so it is appropriate for both static and dynamic image generation

A practical analytic model for daylight

www.cs.utah.edu Figure 1: Left: A rendered image of an outdoor scene with a constant colored sky and no aerial perspective. Right: The same image with a physically-based sky model and physically-based aerial perspective. Sunlight and skylight are rarely rendered correctly in computer graphics. A major reason for this is high computational expense. Another is that precise atmospheric data is rarely available. We present an inexpensive analytic model that approximates full spectrum daylight for various atmospheric conditions. These conditions are parameterized using terms that users can either measure or estimate. We also present an inexpensive analytic model that approximates the effects of atmosphere (aerial perspective). These models are fielded in a number of conditions and intermediate results verified against standard literature from atmospheric science. These models are analytic in the sense that they are simple formulas based on fits to simulated data; no explicit simulation is required to use them. Our goal is to achieve as much accuracy as possible without sacrificing usability

Comparing hospital and telephone follow-up for patients treated for Stage I endometrial cancer 3 (ENDCAT Trial): a randomised, multicentre, non-inferiority trial

Objective To evaluate the effectiveness of nurse-led telephone follow-up (TFU) for Stage I endometrial cancer patients. Design Multicentre, randomised, non-inferiority trial Setting Five centres in the North West of England Sample 259 women treated for Stage I endometrial cancer attending hospital outpatient clinics for routine follow-up Methods Participants were randomly allocated to receive traditional hospital based follow-up (HFU) or nurse-led TFU. Main outcome measures Primary outcomes were psychological morbidity (State Trait Anxiety Inventory, STAI-S) and patient satisfaction with information. Secondary outcomes included patient satisfaction with service, quality of life, and time to detection of recurrence. Results STAI-S scores post-randomisation were similar between groups (mean [SD] TFU 33.0 [11·0], HFU 35.5 [13.0]). The estimated between group difference in STAI was 0·7 (95%CI -1·9 to 3·3); the CI lies above the non-inferiority limit (-3·5) indicating non-inferiority of TFU. There was no significant difference between groups in reported satisfaction with information (OR 0·9, 95% CI 0·4 to 2·1, p=0·83). The HFU group were more likely to report being kept waiting for their appointment (p=0.001), that they did not need any information (p=0.003) and were less likely to report that the nurse knew about their particular case and situation (p=0.005). Conclusions TFU provides an effective alternative to HFU for Stage I endometrial cancer patients, with no reported physical or psychological detriment. Patient satisfaction with information was high, with similar levels between group

Spin dynamics in semiconductors

This article reviews the current status of spin dynamics in semiconductors which has achieved a lot of progress in the past years due to the fast growing field of semiconductor spintronics. The primary focus is the theoretical and experimental developments of spin relaxation and dephasing in both spin precession in time domain and spin diffusion and transport in spacial domain. A fully microscopic many-body investigation on spin dynamics based on the kinetic spin Bloch equation approach is reviewed comprehensively.Comment: a review article with 193 pages and 1103 references. To be published in Physics Reports

Comparing Notes: Recording and Criticism

This chapter charts the ways in which recording has changed the nature of music criticism. It both provides an overview of the history of recording and music criticism, from the advent of Edison’s Phonograph to the present day, and examines the issues arising from this new technology and the consequent transformation of critical thought and practice

Wider Still and Wider: British Music Criticism since the Second World War

This chapter provides the first historical examination of music criticism in Britain since the Second World War. In the process, it also challenges the simplistic prevailing view of this being a period of decline from a golden age in music criticism