Radiosity and raytracing

Radiosity 

Radiosity is the algorithm which is very dependent on light and from which direction the light is hitting the object which creates a ore effective light reflection. 

In more recent times radiosity has become more renowned for being more benfitial over standard lighting effects. There are two main benefits which radiosity has over standard lighting. These are improved Image quality and more lifelike lighting.

Radiosity technology is very prenowned in 3Ds Max which has the ability to produce more accurate photometric simulations of lighting which have been created in specific scenes. Indirect light, soft shadows and colour bleeding between surfaces all produce images in a realstic manner. This is one major benefit because when rendered the image will have a sense of realism hich standard scan line rendering is unable to offer.

In terms of radiosity techniques, 3DS max also provides a real world lighting interface. The light intensity used  is measured using Photometric units. By being able to work with a real life lighting interface, you can effectively set up the lighting for your scenes. Due to this, the user is therefore able to concentrate more on designing the lighting or exploring different lighting effects, rather than in other computer graphic techniques where you are required to visualize them more accurately.

In terms of disadvantage is that even though the image quality is alot better, the rendering time rises and takes alot longer to be rendered.Photometric units are the measurements which are used to measure of lighting.

In terms of differences between local and global illumination rendering algorithms, Local illumination algorithms only tend to describe only how individual sectors like surfaces reflect or transmit light.  Given specific descriptions of light arriving at a surface, these mathmatical algorithms, called shaders in 3Ds Max. These have the ability to predict the intensity, colour and distribution of the light leaving a specific surface.

However Global illuminations only take into acount the ways in how light is transferred between different surfaces. This process is called global illumination algorithms.

An algorithm is a list of instrucitons which define a list of instructions to complete a task, a shader is a set of software instructions, which is used by the graphic resources primarily to perform rendering effects.

3DS max also offers two global illumination algorithms, which have become integral parts of its production rendering system. One key objective of a global illumination algorithms is to re-create, as accurately as possible. 

One of the very first global illumination algorithms that was developed was named as Ray-Tracing.

Raytracing

Raytracing is camera dependent and the reflection is very dependent on the position of the camera. 

A ray is tracerd backwards using from the position of the eye, through the pixel of the monitor, until it encounters a surface. To determine the total illumination, we trace a ray from the point of the encounter to each light source from within the environment, which is named the shadow ray.

One key example of radiosity in terms of a disadvantage using ray-tracing is that radiosity has the ability to calculate diffuse intereflections between surfaces, where as ray-tracing dosent account for interactions using interreflections. Radiosity also offers immediate rendering results,whereas the ray-tracing algorithm does not  offer results immediately, when in fact the rendering of images using ray-tracing depends on the amount of light sources and the process has to be repeated for each of the different viewing angles and is therefore view depending.

In terms of the history of ray-tracing and radiosity, the algorithms came about when researchers began to research alternative techniques for calculating global illumination.

In the early 1960’s engineers developed methods for simulating the radiative heat transfer between surfaces to determine how well there designs would cope under different scrutinous conditions in particular places such as furnaces and engines.

Rather than determine the colour between each pixel on a screen which is ray-tracing, radiosity is a technique which calculates the intensity  for all surfaces in the enironment

Rendering Hardware

One key stage during the 3D development of a particular object, has to rendered at the end of the process for the object to be complete. In this post i am going to be stating simple facts about rendering hardware and its capabilities.

API

Firstly an API in rendering terms, is  named Application Programming Interface. An API is the initial interface which is between a 3D Application and the hardware which is being used to render the object. The main function, this usually happens after all the steps in the animation process have been completed.

GPU 

The next point in relation to rendering hardware is a GPU. A GPU stands for graphics processing unit. A GPU is a dedicated graphics rendering tool for a number of media consoles, such as PC and Games console.

“A GPU implements a number of graphics primitive operations in a way that makes running them much faster than drawing directly to the screen with the host CPU.”

http://en.wikipedia.org/wiki/GPU

Throughout the history, GPU’s have developed mainly from the moonlithic graphic chip’s of the early 1980’s and 90’s. The first gaming console to use a style of  a GPU was the commadore amiga in the early 1980’s.

amiga1k.jpg

Shader’s

 A shader is a something is something which has the ability to define final surface properties, such as Colour, lighting and reflectivity, and transluscency of a surface.

Both the DirectX and OpenGL graphic libraries use three types of shaders. These are Vertex shader which only effect certain series of vertices and can therefore only effect vertex properties like position, color, and texture coordinate.

Rendering Engine

A rendering engine is a process which generates an image from a model.  The main model is a description of 3D objects from a data structure. The image contans information from points such as geometry, viewpoint, texture, lighting, and shading.

Rendering is used in many forms of media entertainment to render final productions.

Some of these include;

video games,

simulators,

movie or TV special effects, and design visualization.

Each of these forms of entertainment use differing amounts of balance and technique.

Why SGI graphics are considered to be important in the development of hardware renderers?

Silicon graphics are considered to play such a key role in the development of hardware renderers as silicon graphics were the founders of Open GL graphics.

James Clarke

James Clarke is a very well know entrepeneur who  formally specialised in in comouter scientists. In the more recent times he hs founded several notiable companies under the silicon Valley technology.

The reason why James Clarke is one of the most notable founders in computer graphics is because his research into computer graphics led to the development of systems for fast rendering of computer images.

Pro’s  and cons of Open GL and Direct X shaders

Open GL

The Open GL Shader is cross Platform,

Open GL is very portable and is able to be used in a variety of situations and is very straight forward to use.

Open GL is unlikely to evolve at a fast rate.

Direct X

DirectX supports a greater set of features.

DirectX gives programmers a great deal of control over the rendering pipeline if they want it.  DirectX 9.0 features programmable pixel and vertex shaders

Direct X has better support for modern chipset features.

Direct X also is very straightforward however, this is not cross platform like the open GL, where as the direct X can in many cases only work on the Windows Platform.

However it has some driver issues.

DirectX is not portable and probably never will be.