Fast self-shadowing using occluder textures

A real-time self-shadowing technique is described. State of the art shadowing techniques that utilize modern hardware often require multiple rendering passes and introduce rendering artifacts. Combining separate ideas from earlier techniques which project geometry onto a plane and project imagery onto an object results in a new real-time technique for self-shadowing. This technique allows an artist to construct occluder textures and assign them to shadow planes for a self-shadowed model. Utilizing a graphics processing unit (GPU), a vertex program computes shadowing coordinates in real-time, while a fragment program applies the shading and shadowing in a single rendering pass. The methodology used to create shadow planes and write the vertex and fragment programs is given, as well as the relation to the previous work. This work includes implementing this technique, applying it to a small set of test models, describing the types of models for which the technique is well suited, as well as those for which it is not well suited, and comparing the techniqueâÂÂs performance and image quality to other state of the art shadowing techniques. This technique performs as well as other real-time techniques and can reduce rendering artifacts in certain circumstances

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

Smoke and Shadows: Rendering and Light Interaction of Smoke in Real-Time Rendered Virtual Environments

Realism in computer graphics depends upon digitally representing what we see in the world with careful attention to detail, which usually requires a high degree of complexity in modelling the scene. The inevitable trade-off between realism and performance means that new techniques that aim to improve the visual fidelity of a scene must do so without compromising the real-time rendering performance. We describe and discuss a simple method for realistically casting shadows from an opaque solid object through a GPU (graphics processing unit) based particle system representing natural phenomena, such as smoke

Shadow Mapping or Shadow Volume?

In this paper two techniques of shadow generation are described. Volume shadow is geometric base but shadow mapping is image base. Silhouette detection is a most expensive step to create volume shadow. Two algorithms to recognize silhouette are introduced. Stencil buffer and Z- buffer are two other tools for creating shadow by volume shadow technique. Both algorithms are implemented in virtual environment with moveable light source. Triangular method and the Visible-non visible method are introduced. The recent traditional silhouette detection and implementation techniques used in volume shadow algorithm are improved. With introduce flowchart of both algorithms, the last volume shadow algorithm using stencil buffer is rewritten. A very simple algorithm to create volume shadow is proposed. The last shadow mapping algorithm is rewritten. These techniques are poised to bring realism into commercial games. It may be use in virtual reality applications

To Combine Silhouette Detection and Stencil Buffer for Generating Real-Time Shadow

This paper describes one of the best methods to generate real-time shadow that called volume shadow. Volume shadow algorithm is possible to implement for virtual environment with moveable illuminated light source. We improve to find silhouette and implementation of the last techniques used in shadow volume algorithms, and limitation of length of volume of each semi-polygon that makes between silhouette's edge and shadow receiver. We rewrite the last volume shadow algorithm using stencil buffer and propose a pseudo code in OpenGl. The best tools that we have used in this algorithm are stencil buffer and Z-buffer.It makes realistic commercial games or it can be use in virtual reality systems

Efficient algorithms for occlusion culling and shadows

The goal of this research is to develop more efficient techniques for computing the visibility and shadows in real-time rendering of three-dimensional scenes. Visibility algorithms determine what is visible from a camera, whereas shadow algorithms solve the same problem from the viewpoint of a light source. In rendering, a lot of computational resources are often spent on primitives that are not visible in the final image. One visibility algorithm for reducing the overhead is occlusion culling, which quickly discards the objects or primitives that are obstructed from the view by other primitives. A new method is presented for performing occlusion culling using silhouettes of meshes instead of triangles. Additionally, modifications are suggested to occlusion queries in order to reduce their computational overhead. The performance of currently available graphics hardware depends on the ordering of input primitives. A new technique, called delay streams, is proposed as a generic solution to order-dependent problems. The technique significantly reduces the pixel processing requirements by improving the efficiency of occlusion culling inside graphics hardware. Additionally, the memory requirements of order-independent transparency algorithms are reduced. A shadow map is a discretized representation of the scene geometry as seen by a light source. Typically the discretization causes difficult aliasing issues, such as jagged shadow boundaries and incorrect self-shadowing. A novel solution is presented for suppressing all types of aliasing artifacts by providing the correct sampling points for shadow maps, thus fully abandoning the previously used regular structures. Also, a simple technique is introduced for limiting the shadow map lookups to the pixels that get projected inside the shadow map. The fillrate problem of hardware-accelerated shadow volumes is greatly reduced with a new hierarchical rendering technique. The algorithm performs per-pixel shadow computations only at visible shadow boundaries, and uses lower resolution shadows for the parts of the screen that are guaranteed to be either fully lit or fully in shadow. The proposed techniques are expected to improve the rendering performance in most real-time applications that use 3D graphics, especially in computer games. More efficient algorithms for occlusion culling and shadows are important steps towards larger, more realistic virtual environments.reviewe

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 Overview on Base Real-Time Shadow Techniques in Virtual Environments

Shadows are elegant to create a realistic scene in virtual environments. Variety types of shadow techniques encourage us to prepare an overview on all base shadow techniques. Non real-time and real-time techniques are big subdivision of shadow generation. In non real-time techniques ray tracing, ray casting and radiosity are well known and deeply described. Radiosity implemented to create very realistic shadow on non real-time scene. Although traditional radiosity algorithm is difficult to implement, we have proposed a simple one. The proposed pseudo code is easier to understand and implement. Ray tracing used to prevent of collision of movement objects. Projection shadow, shadow volume and shadow mapping are used to create real-time shadow in virtual environments. We have used projection shadow for some objects are static and have shadow on flat surface. Shadow volume used to create accurate shadow with sharp outline. Shadow mapping that is the base of most recently techniques is reconstructed. The reconstruct algorithm gives some new idea to propose another algorithm based on shadow mapping.  

Fluids real-time rendering

In this thesis the existing methods for realistic visualization of uids in real-time are reviewed. The correct handling of the interaction of light with a uid surface can highly increase the realism of the rendering, therefore method for physically accurate rendering of re ections and refractions will be used. The light- uid interaction does not stop at the surface, but continues inside the uid volume, causing caustics and beams of light. The simulation of uids require extremely time-consuming processes to achieve physical accuracy and will not be explored, although the main concepts will be given. Therefore, the main goals of this work are: Study and review the existing methods for rendering uids in realtime. Find a simpli ed physical model of light interaction, because a complete physically correct model would not achieve real-time. Develop an application that uses the found methods and the light interaction model