Hierarchical subdivision techniques remove the need for a-priori meshing of surfaces when approximating global illumination. In addition they allow progressive re nement of the solution. However, when subdivision is based upon Monte Carlo methods, due to the stochastic nature of such techniques, subdivision decisions cannot be made unless a su ciently large number of samples have been considere...

Cloud-related shadows represent areas with low illumination conditions that affect remote sensing image quality. In this research, a wavelet-based image sharpening algorithm was developed to enhance shadow areas independently using the defected cloudy image information. The developed algorithm is applied locally by boosting the image high frequency content in the shadow areas using the defected...

Shadow detection for single image is difficult but has wide applications. This paper proposes a novel and fast shadow detection method based on the Tricolor Attenuation Model [1]. In this study, we analyze the spectral property of outdoor light sources to estimate the parameters of TAM. Then our shadow detection method is proposed by integrate the TAM feature and intensity information. Our meth...

F or the past six years, three remotely controlled fluoroscopic units equipped with rotating cradles and overhead tube light localizers have been used for percutaneous lung biopsies under fluoroscopic control with angulation of the fluoroscopic beam and rotation of the patients in a rotating cradle. The purpose of using this equipment was to plan our biopsy procedures traversing a minimum dista...

One of the most demanding challenges for real-time shadow algorithms is their application to large-scale, polygon-rich and dynamic environments. In this paper, we discuss the major problems encountered in applying shadow maps to such an environment and provide practical and robust solutions to the appearing problems. We tackle projection aliasing with the aid of an eye space blur. We compare th...

The blind cavefish Astyanax mexicanus undergoes bilateral eye degeneration during embryonic development. Despite the absence of light in the cave environment, cavefish have retained a structurally intact pineal eye. We show here that contrary to visual degeneration in the bilateral eyes, the cavefish pineal eye has conserved the ability to detect light. Larvae of two different Astyanax cavefish...

A new algorithm to eliminate moving cast shadow for robust vehicle detection and extraction in a vision-based highway monitoring system is investigated in this research. The proposed algorithm is based on a simplified 2D vehicle/shadow model of six types projected to a 2D image plane. Parameters of the joint 2D vehicle/shadow models can be estimated from input video without the light source and...

Hierarchical subdivision techniques remove the need for a-priori meshing of surfaces when approximating global illumination. In addition they allow progressive reenement of the solution. However, when subdivision is based upon Monte Carlo methods, due to the stochastic nature of such techniques, subdivision decisions cannot be made unless a suuciently large number of samples have been considere...

The image of an object and of the shadow it casts on a planar surface provides important cues for three-dimensional (3D) stance recovery. We assume that the position of the plane on which the shadow lies with respect to a pinhole camera is known and that the position of the light source is unknown. If the light source is sufficiently far away that parallel projection may be assumed, then knowle...