Given the location of shadows, how can we obtain highquality shadow-free images? Several methods have been proposed so far, but they either introduce artifacts or can be difficult to implement. We propose here a simple method that results in virtually error and shadow-free images in a very short time. Our approach is based on the insight that shadow regions differ from their shadow-free counter...

High-quality shadow anti-aliasing is a challenging problem in shadow mapping. Revectorization-based shadow mapping (RBSM) minimizes shadow aliasing by revectorizing the jagged shadow edges generated with shadow mapping, keeping low memory footprint and real-time performance for the shadow computation. However, the current implementation of RBSM is not so well optimized because its visibility fu...

This paper describes a real-time shadow generation algorithm for polygonal environments illuminated by movable point light sources. The main goal is to quickly reduce the number of hidden shadow volumes, by using a technique of volumetric shadow rendering using stencil buffers with a modified BSP tree, i.e. a simplified version of a SVBSP (Shadow Volume BSP) tree. It also provides new easy-to-i...

In recent years , both Williams’ original Z-buffer shadow mapping algorithm [Williams 1978] and Crow’s shadow volumes [Crow 1977] have seen many variations, additions and enhancements, greatly increasing the visual quality and efficiency of renderings using these techniques. Additionally, the fast evolution of commodity graphics hardware allows for a nearly complete mapping of these algorithms ...

We present an interactive, robust and high quality method for fast shadow removal. To perform detection we use an on-the-fly learning approach guided by two rough user inputs for the pixels of the shadow and the lit area. From this we derive a fusion image that magnifies shadow boundary intensity change due to illumination variation. After detection, we perform shadow removal by registering the...

Advanced segmentation techniques in the surveillance domain deal with shadows to avoid distortions when detecting moving objects. Most approaches for shadow detection are still typically restricted to penumbra shadows and cannot cope well with umbra shadows. Consequently, umbra shadow regions are usually detected as part of moving objects, thus affecting the performance of the final detection. ...

In the context of mixed reality, it is difficult to simulate shadow interaction between real and virtual objects when only an approximate geometry of the real scene and the light source is known. In this paper, we present a realtime rendering solution to simulate colour-consistent virtual shadows in a real scene. The rendering consists of a three-step mechanism: shadow detection, shadow protect...

Corruption and the Shadow Economy: An Empirical Analysis This paper analyzes the influence of the shadow economy on corruption and vice versa. We hypothesize that corruption and shadow economy are substitutes in high income countries while they are complements in low income countries. The hypotheses are tested for a crosssection of 120 countries and a panel of 70 countries for the period 1994-2...

This paper introduces a new concept within shadow segmentation for usage in shadow removal and augmentation through construction of an alpha overlay shadow model. Previously, an image was considered to consist of shadow and non-shadow regions. We construct a model that accounts for sunlit, umbra and penumbra regions. The model is based on theories about color constancy, daylight, and the geomet...

Acquisition of hyperspectral imagery (HSI) from cameras mounted on terrestrial platforms is a relatively recent development that enables spectral analysis of dominantly vertical structures. Although solar shadowing is prevalent in terrestrial HSI due to the vertical scene geometry, automated shadow detection and restoration algorithms have not yet been applied to this capture modality. We inves...