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...

let $r$ be a commutative ring with identity. let $g(r)$ denote the maximal graph associated to $r$, i.e., $g(r)$ is a graph with vertices as the elements of $r$, where two distinct vertices $a$ and $b$ are adjacent if and only if there is a maximal ideal of $r$ containing both. let $gamma(r)$ denote the restriction of $g(r)$ to non-unit elements of $r$. in this paper we study the various graphi...

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...

We propose an efficient and light-weight solution for rendering smooth shadow boundaries that do not reveal the tessellation of the shadow-casting geometry. Our algorithm reconstructs the smooth contours of the underlying mesh and then extrudes shadow volumes from the smooth silhouettes to render the shadows. For this purpose we propose an improved silhouette reconstruction using the vertex nor...

Shadow maps are a widely used means for the generation of shadows although they exhibit aliasing artifacts and problems of numerical precision. In this paper we extend the concept of a single shadow map by introducing dual shadow maps, which are based on the two depth layers that are closest to the light source. Our shadow algorithm takes into account these two depth values and computes an adap...

Shadows appear in many scenes. Shadows in images are typically affected by several phenomena in the scene, such as lighting conditions, type and behavior of shadowed surfaces, occluding objects etc. One of the core issues is to detect the shadow accurately. Accurate shadow detection can be difficult due to the illumination variations of the background and similarity between appearance of the ob...

The role of shadow is important in cartoon animation. Shadows in hand-drawn animation reflect the expression of the animators' style, rather than mere physical phenomena. However shadows in 3DCG cannot express such an animators' touch. In this paper we propose a novel method for editing the shadow with both advantages of hand drawn animation and 3DCG technology. In particular, we discuss two ph...