Successfully detecting shadows in still images is challenging yet has wide applications. Shadow properties and features are very important for shadow detection and processing. The aim of this work is to find some new physical properties of shadows and use them as shadow features to design an effective shadow detection method for outdoor color images. We observe that although the spectral power ...

To escape competition at the dung pile, a ball-rolling dung beetle forms a piece of dung into a ball and rolls it away. To ensure their efficient escape from the dung pile, beetles rely on a 'celestial compass' to move along a straight path. Here, we analyzed the reliability of different skylight cues for this compass and found that dung beetles rely not only on the sun but also on the skylight...

We present a fast technique for the simulation of accumulated snow. Our technique is based on two phenomena; local occlusion of small holes and ditches, and the global influence of a skylight. We use ambient occlusion to predict the shape and location of snow accumulation and direct illumination from the skylight to simulate the melting and sublimation of snow as dissipation. The snow is simula...

abstract natural light has a great effect on the health of human beings. studies on iranian old houses show that various apertures were used to provide natural light in the interior spaces of   the buildings. in the present research attempt has been made to measure the extent to which some of the lightening methods of iranian traditional architecture have been successful in the provision of int...

In a previous work [J. Opt. Soc. Am. A24, 942 (2007)JOAOD60740-323210.1364/JOSAA.24.000942] we made a complete theoretical and computational study of the influence of several parameters on the behavior of a planned multispectral system for imaging skylight, including the number of sensors and the spectral estimation algorithm. Here we follow up this study by using all the information obtained i...