Shadows generation using geometry shaders

Algorithms for simulating shadows are considered. A shadow volume method using geometry shaders is proposed

Real-Time Shadow Using a Combination of Stencil and The Z-Buffer

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 shadow volume algorithms using stencil buffers especially in order to recognize silhouette, reduce the number of shadow polygons and also redundant length of each triangles that makes the volume shadow. This work may be applied in commercial games or other virtual reality systems

Penumbra maps: approximate soft shadows in real-time

Journal ArticleGenerating soft shadows quickly is difficult. Few techniques have enough flexibility to interactively render soft shadows in scenes with arbitrarily complex occluders and receivers. This paper introduces the penumbra map, which extends current shadow map techniques to interactively approximate soft shadows. Using object silhouette edges, as seen from the center of an area light, a map is generated containing approximate penumbral regions. Rendering requires two lookups, one into each the penumbra and shadow maps. Penumbra maps allow arbitrary dynamic models to easily shadow themselves and other nearby complex objects with plausible penumbrae

Penumbra maps

technical reportGenerating soft shadows quickly is difficult. Few techniques have enough flexibility to interactively render soft shadows in scenes with arbitrarily complex occluders and receivers. This paper introduces the penumbra map, which extends current shadow map techniques to interactively approximate soft shadows. Using object silhouette edges, as seen from the center of an area light, a map is generated containing approximate penumbral regions. Rendering requires two lookups, one into each the penumbra and shadow maps. Penumbra maps allow arbitrary dynamic models to easily shadow themselves and other nearby complex objects with plausible penumbrae

Real-Time Shadow Using a Combination of Stencil and The Z-Buffer

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 shadow volume algorithms using stencil buffers especially in order to recognize silhouette, reduce the number of shadow polygons and also redundant length of each triangles that makes the volume shadow. This work may be applied in commercial games or other virtual reality systems

An empirically derived system for high-speed shadow rendering

Shadows have captivated humanity since the dawn of time; with the current age being no exception – shadows are core to realism and ambience, be it to invoke a classic Baroque interplay of lights, darks and colours as the case in Rembrandt van Rijn’s Militia Company of Captain Frans Banning Cocq or to create a sense of mystery as found in film noir and expressionist cinematography. Shadows, in this traditional sense, are regions of blocked light – the combined effect of placing an object between a light source and surface. This dissertation focuses on real-time shadow generation as a subset of 3D computer graphics. Its main focus is the critical analysis of numerous real-time shadow rendering algorithms and the construction of an empirically derived system for the high-speed rendering of shadows. This critical analysis allows us to assess the relationship between shadow rendering quality and performance. It also allows for the isolation of key algorithmic weaknesses and possible bottleneck areas. Focusing on these bottleneck areas, we investigate several possibilities of improving the performance and quality of shadow rendering; both on a hardware and software level. Primary performance benefits are seen through effective culling, clipping, the use of hardware extensions and by managing the polygonal complexity and silhouette detection of shadow casting meshes. Additional performance gains are achieved by combining the depth-fail stencil shadow volume algorithm with dynamic spatial subdivision. Using this performance data gathered during the analysis of various shadow rendering algorithms, we are able to define a fuzzy logic-based expert system to control the real-time selection of shadow rendering algorithms based on environmental conditions. This system ensures the following: nearby shadows are always of high-quality, distant shadows are, under certain conditions, rendered at a lower quality and the frames per second rendering performance is always maximised.Dissertation (MSc)--University of Pretoria, 2009.Computer Scienceunrestricte

APPLYING THE REAL TIME SHADOWING METHOD FOR CREATING SOFT SHADOWS IN OPENGL

This paper presents a technique for rapidly generating and rendering of soft shadows on the scene. The method has the advantage of real-time creating of shadows which look more realistic than hard shadows and have high quality, also it has not high demands in resources. The main idea is to replace a complex light source with a collection of multiple point sources of light in order to decrease rendering time. The mathematic model, experiments, and comparison with similar techniques are given and described

Real-time shadows in OpenGL caused by the presence of multiple light sources

U suvremenoj računalnoj grafici naglasak je na detaljima prizora, a uzimajući u obzir poboljšanja hardverskih svojstava, nije dopušteno raditi kompromise kada je riječ o stvarnosti scena. Svaki odraz, sjena, zaobljeni kut ili prozirnost mora biti doveden do savršenstva i prikazan u cilju da se scena koja se oslikava učini što realističnijom. U jednom od najšire rabljenih API-ja za renderiranje 3D objekata, OpenGL-u, ne postoji nešto poput knjižnice za dodavanje ovih pojava koje postoje u stvarnosti. Ako se razmatra mogućnost postojanja više izvora svjetlosti, renderiranje svih ovih detalja postaje pravi izazov. Cilj ovog rada je obezbjeđivanje metoda za generiranje sjene na efikasan način, za objekte često rabljene kao komponente složenih 3D objekata, u uvjetima prisutnosti više svjetlosnih izvora s mogućnošću kretanja.In modern computer graphics, the emphasis is on the details of the scene, and taking into account the improvements in hardware performances, it is not allowed to make compromises when it comes to the reality of scenes. Each reflection, shadow, rounded corner and transparency must be brought to perfection and presented in order to make a depicted scene more realistic. In one of the most widely used API for rendering 3D objects, OpenGL, there is nothing similar to a library for adding those phenomena that exist in reality. If the possibility of existence of multiple light sources is considered, rendering all these details becomes a real challenge. The aim of this paper is to provide a method for generating shadows in an efficient way, for the objects commonly used as components of complex 3D objects, in conditions of the presence of moving light sources