This paper compares two methods for estimating illumination distributions from shadows: methods using self shadows and cast shadows. The cast shadow method provides an effective framework for recovering illuminations in a real scene utilizing variations of image brightnesses inside shadows cast by an occluding object of known shape. The shadow surface is typically the same plane on which the ob...

— This paper describes an efficient algorithm to model the light attenuation due to a participating media with low albedo. Here, we consider the light attenuation along a ray, as well as the light attenuation emanating from a surface. The light attenuation is modeled using a splatting volume renderer for both the viewer and the light source. During the rendering, a 2D shadow buffer accumulates ...

This paper describes a robust method for estimating, in a reliable manner, the illumination distribution of a real scene from shadows in a given image. In general, shadows in a scene are caused by the occlusion of incoming light; image brightness inside shadows have a great potential for providing distinct clues to the illumination distribution of the scene. Taking advantage of this fact, we re...

It is unclear how shadows are processed in the visual system. Whilst shadows are clearly used as an important cue to localise the objects that cast them, there is mixed evidence regarding the extent to which shadows influence the recognition of those objects. Furthermore experiments exploring the perception of shadows per se have provided evidence that the visual system has less efficient acces...

The most popular methods for interactive hard shadows rendering are shadow volumes and shadow maps. Shadow volumes generate precise shadows but require high fill rate. Due to excessive fill rate requirements, shadow maps are probably the most widely used means for generation of shadows, despite their well known aliasing problems. In this paper, Extended Shadow Maps are introduced, as a means to...

Some aspects of lightlike dimensional reduction in flat spacetime are studied with emphasis to classical applications. Among them the Galilean transformation of shadows induced by inertial frame changes is studied in detail by proving that, (i) the shadow of an object has the same shape in every orthogonal-to-light screen, (ii) if two shadows are simultaneous in an orthogonal-to-light screen th...

Shadows provide important visual hints about the spatial relationship between objects. Shadow volumes are one way to generate sophisticated shadows for use in real time environments. This paper focuses on the geometric aspects which are involved in the creation of the shadow volume. Speed up techniques like shaders and dual space approaches for silhouette determination are discussed. Finally th...

A major problem with interactive displays based on front projection is that users cast undesirable shadows on the display surface. This paper demonstrates that shadows can be muted by redundantly illuminating the display surface using multiple projectors, all mounted at different locations. However, this technique alone does not eliminate shadows: Multiple projectors create multiple dark region...

Identifying moving objects from a video sequence is a fundamental and critical task in many computer vision applications and a robust segmentation of motion objects from the static background is generally required. Segmented foreground objects generally include their self shadows as foreground objects since the shadow intensity differs and gradually changes from the background in a video sequen...

In ultrasound images, acoustic shadows appear as regions of low signal intensity linked to boundaries with very high acoustic impedance differences. Acoustic shadows can be viewed either as informative features to detect lesions or calcifications, or as damageable artifacts for image processing tasks such as segmentation, registration or 3D reconstruction. In both cases, the detection of these ...