Many computer vision algorithms, such as segmentation, tracking, and stereo registration, are confounded by shadows in images. Hence finding shadows in colour images is an important research issue. As opposed to the majority of techniques, which either need a sequence of images or require geometric information on images, this paper proposes an illuminant discontinuity measure by which shadow ed...

The computation of soft shadows created by area light sources is a well-known problem in computer graphics. Due to the complexity of the problem, soft shadows commonly are generated only for images that are rendered in an off-line process. In interactive virtual environments, where images have to be computed in real time, soft shadows are mostly replaced by hard shadows as this takes much less ...

This paper introduces a novel system for automatic detection and height estimation of buildings with polygonal shape roofs in singular satellite images. The system is capable of detecting multiple flat polygonal buildings with no angular constraints or shape priors. The proposed approach employs image primitives such as lines, and line intersections, and examines their relationships with each o...

One of the greatest challenges for vision-based road detection is the presence of shadows and other vehicles. It’s particularly challenging to detect unstructured road when it has both shadowed and non shadowed area since the presence of shadows can cause hindrance and shape distortion of objects which may result in false detection of road. Shadows can also cause a significant problem in road d...

This paper describes an algorithm for simulating soft shadows at interactive rates using graphics hardware. On current graphics workstations, the technique can calculate the soft shadows cast by moving, complex objects onto multiple planar surfaces in about a second. In a static, diffuse scene, these high quality shadows can then be displayed at 30 Hz, independent of the number and size of the ...

The accurate generation of soft shadows is a particularly computationally intensive task. In order to reduce rendering time, most real-time and offline applications decorrelate the generation of shadows from the computation of lighting. In addition to such approximations, they generate shadows using some restrictive assumptions only correct in very specific cases, leading to penumbra over-estim...

In this paper, we present a new method for removing shadows from images. First, shadows are detected by interactive brushing assisted with a Gaussian Mixture Model. Second, the detected shadows are removed using an adaptive illumination transfer approach that accounts for the reflectance variation of the image texture. The contrast and noise levels of the result are then improved with a multi-s...

Shadows provide a strong source of information about the shapes of surfaces. We analyze the local geometric structure of shadow contours on piecewise smooth surfaces. Particular attention is paid to intrinsic shadows on a surface: that is, shadows created on a surface by the surface's own shape and placement relative to a light source. Intrinsic shadow contours provide useful information about ...

Efficiently computing robust soft shadows is a challenging and time consuming task. On the one hand, the quality of image-based shadows is inherently limited by the discrete property of their framework. On the other hand, object-based algorithms do not exhibit such discretization issues but they can only efficiently deal with triangles having a constant transmittance factor. This paper addresse...

This paper introduces a hybrid approach that is based on color information that utilizes a mask and K-Means clustering algorithm along with the frame averaging background subtraction technique. This hybrid approach efficiently removes artifacts caused by lightening changes such as highlight and reflection from segmentation, while also successfully removing shadows of stationary objects and dark...