Efficient light scattering through thin semi-transparent objects

This paper concerns real-time rendering of thin semi-transparent objects. An object in this category could be a piece of cloth, eg. a curtain. Semi-transparent objects are visualized most correctly using volume rendering techniques. In general such techniques are, however, intractable for real-time applications. Surface rendering is more efficient, but also inadequate since semi-transparent objects should have a different appearance depending on whether they are front-lit or back-lit. The back-lit side of a curtain, for example, often seems quite transparent while the front-lit side seems brighter and almost opaque. To capture such visual effects in the standard rendering pipeline, Blinn [1982] proposed an efficient local illumination model based on radiative transfer theory. He assumed media of low density, hence, his equations can render media such as clouds, smoke, and dusty surfaces. Our observation is that Chandrasekhar [1960] has derived the same equations from a different set of assumptions. This alternative derivation makes the theory useful for realistic real-time rendering of dense, but thin, semitransparent objects such as cloth. We demonstrate that application of the theory in this new area gives far better results than what is obtainable with a traditional real-time rendering scheme using a constant factor for alpha blending

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Functional distinctiveness of major plant lineages

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106060/1/jec12208.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/106060/2/jec12208-sup-0001-Supp_Info.pd

Relation of child, caregiver, and environmental characteristics to childhood injury in an urban Aboriginal cohort in New South Wales, Australia

Objective : Despite being disproportionately affected by injury, little is known about factors associated with injury in Aboriginal children. We investigated factors associated with injury among urban Aboriginal children attending four Aboriginal Community Controlled Health Services in New South Wales, Australia. Methods : We examined characteristics of caregiver-reported child injury, and calculated prevalence ratios of ‘ever-injury’ by child, family, and environmental factors. Results : Among children in the cohort, 29% (n=373/1,303) had ever broken a bone, been knocked out, required stitches or been hospitalised for a burn or poisoning; 40–78% of first injuries occurred at home and 60–91% were treated in hospital. Reported ever-injury was significantly lower (prevalence ratio ≤0.80) among children who were female, younger, whose caregiver had low psychological distress and had not been imprisoned, whose family experienced few major life events, and who hadn’t experienced alcohol misuse in the household or theft in the community, compared to other cohort members. Conclusions : In this urban Aboriginal child cohort, injury was common and associated with measures of family and community vulnerability. Implications for public health : Prevention efforts targeting upstream injury determinants and Aboriginal children living in vulnerable families may reduce child injury. Existing broad-based intervention programs for vulnerable families may present opportunities to deliver targeted injury prevention. Key words : Aboriginal child health, child injury, social determinants of health, injury prevention, Aboriginal Community Controlled Health ServicesKF is supported by an NHMRC Early Career Fellowship (#1016475) and an NHMRC capacity building grant (#573122). EB is supported by the National Health and Medical Research Council of Australia (grant number 1042717)