Given a set of n non-overlapping unit disks in the plane, a line ` is called blocked if it intersects at least one of the disks and a point p is called a shadow point if all lines containing p are blocked. In addition, a maximal closed set of shadow points is called a shadow region. We derive properties of shadow regions, and present an O(n) algorithm that outputs all shadow regions. We prove t...

Shadows cause problems in image processing. In this paper, a new methodology for shadow removal based on Strong Edge Detection (SED) method is proposed. The strong shadow edges are recognized by learning the patch based characteristics of shadow edges and then image features are analyzed to guide a Shadow Edge Classifier. Also, spatial patch smoothing is used to enforce uniformity between adjac...

Rendering high-quality shadows in real-time is a challenging problem. Shadow mapping has proved to be an efficient solution, as it scales well for complex scenes. However, it suffers from aliasing problems. Filtering the shadow map alleviates aliasing, but unfortunately, native hardware-accelerated filtering cannot be applied, as the shadow test has to take place beforehand. We introduce a simp...

Shadow maps are a very efficient means to add shadows to arbitrary scenes. In this paper, we introduce Translucent Shadow Maps, an extension to shadow maps which allows very efficient rendering of sub-surface scattering. Translucent Shadow Maps contain depth and incident light information. Sub-surface scattering is computed on-the-fly during rendering by filtering the shadow map neighborhood. T...

In this paper we describe a real-time shadow generation with volume shadow algorithm in virtual environment that is illuminated by light sources with possibility to move separately. This algorithm uses the combination of stencil and Z-buffers to generate shadow volume. It is simple to understand and implement. We have significantly improved and implemented recent techniques that are used in sha...

An algorithm is presented for constructing shadow volumes for CSG objects. For each primitive solid, the algorithm calculates a tree of shadow volumes to model the shadows generated by the shadow-generating parts of the boundary of the primitive. The shadow of the complete CSG object is the union of these shadow trees. An implementation of the algorithm is described for a scan-line display algo...

Purpose – Shadows, the common phenomena in most outdoor scenes, bring many problems in practical image processing. Shadow detection and removal, especial in uncalibrated outdoor image, is still a difficult problem. The purpose of this paper is to detect and to remove shadows in single outdoor image based on retinex theory. Design/methodology/approach – The shadow extraction algorithm originates...

Shadow generation has always been a big problem in real-time 3D graphics. Determining whether a point is in shadow is not a trivial operation for modern GPUs, particularly because GPUs work in terms of rasterizing polygons instead of ray tracing. Today's shadows should be completely dynamic. Almost every object in the scene should cast and receive shadows, there should be self-shadowing, and ev...

The shadow is one of the basic features of remote sensing images, especially high resolution remote sensing images, and greatly reduces the information of earth targets. The detection and compensation of shadow is important hotspot and difficulty of remote sensing image processing. In view of the present shadow detection and compensation characteristics of remote sensing image, this paper puts ...

In this paper we propose several methods that can greatly improve image quality when using the shadow mapping algorithm. Shadow artifacts introduced by shadow mapping are mainly due to low resolution shadow maps and/or the limited numerical precision used when performing the shadow test. These problems especially arise when the light source’s viewing frustum, from which the shadow map is genera...