Viewing angle

Abstract: Proposes a generalized split-window method for retrieving land-surface temperature (LST) from AVHRR and MODIS data. Accurate radiative transfer simulations show that the coefficients in the split-window algorithm for LST must vary with the viewing angle, if the authors are to achieve a LST accuracy of about 1 K for the whole scan swath range (/spl plusmn/55/spl deg/ from nadir) and for the ranges of surface temperature and atmospheric conditions over land, which are much wider than those over oceans. The authors obtain these coefficients from regression analysis of radiative transfer simulations, and they analyze sensitivity and error over wide ranges of surface temperature and emissivity and atmospheric water vapor abundance and temperature. Simulations show that when atmospheric water vapor increases and viewing angle is larger than 45/spl deg/, it is necessary to optimize the split-window method by separating the ranges of the atmospheric water vapor, lower boundary temperature, and the surface temperature into tractable subranges. The atmospheric lower boundary temperature and (vertical) column water vapor values retrieved from HIRS/2 or MODIS atmospheric sounding channels can be used to determine the range for the optimum coefficients of the split-window method. This new algorithm not only retrieves land-surface temperature more accurately, but is also less sensitive to uncertainty in emissivity and to instrument quantization error.

Abstract: We present the ALOI collection of 1,000 objects recorded under various imaging circumstances. In order to capture the sensory variation in object recordings, we systematically varied viewing angle, illumination angle, and illumination color for each object, and additionally captured wide-baseline stereo images. We recorded over a hundred images of each object, yielding a total of 110,250 images for the collection. These images are made publicly available for scientific research purposes.

Abstract: THE leading technology for flat, high-resolution computer and television screens is based on twisted nematic liquid-crystal displays1. The successful operation of these displays requires control of molecular alignment, which is currently achieved by confining the liquid crystal between mechanically rubbed surfaces2. But in addition to the practical difficulties associated with rubbing, the resulting displays suffer from restricted viewing angles arising from the uniaxial nature of the alignment process3,4. This latter problem can in principle be circumvented if molecular alignment is varied, in a controlled manner, within individual pixels5–9. Exposure of functionalized substrates to polarized light offers a means of achieving high-resolution patterns in the plane of the display10–12. But to ensure that the alignment pattern imposed on the liquid crystal is free of orientation defects, the tilt angle between the long molecular axes and the substrates must be precisely controlled13,14. Here we show how our earlier linear photoalignment strategy10,12 can be extended to obtain such control, and thereby fabricate stable, multi-domain pixel displays with markedly improved fields of view.

Abstract: Reflective full-color liquid-crystal displays (LCDs) are attracting a great deal of interest as portable information systems because of their extremely low power consumption and light weight; also, the color does not wash out in outdoor use. In this article, reflective LCDs are classified into three types. Among them, the diffusing-reflector type and the front-diffusing film type are suitable for high-quality active-matrix displays. Diffusing-reflector LCDs have the advantage of uniform reflectance at the desired viewing angle due to the design of the surface microstructure of the reflector. Front-diffusing film LCDs using metallic mirrors and an optimally designed light-controlling film enable high contrast in a wide viewing-angle range and uniform reflectance with no blurring. Thus, both types have a high potential for achieving excellent color quality comparable to printed paper. In the near future, these reflective LCDs will likely be applied not only to portable systems, but also to high-performance wireless monitor displays and various other information systems.