Radiosity & raytracing

What is Radiosity

There is two types of global illumination. There is ray tracing and there is radiosity. Radiosity is a rendering technology that simulates lighting effects onto an environment in ways that better simulate real light than standard program slighing could do. The quality of radiosity lighting can clearly be seen as superior to standard light when directly compared

Radiosity lighting vs Standard lighting

Whereas standard lighting uses scanline rendering which works row by row giving linear detail, radiosity works pixel by pixel allowing lighting and the shadows cast by the lighting to be more defined to where it touches, the effect of this can be described as an ink blot on wet paper. Radiosity also has indirect lighting where standard lighting creates nothing more than a silhouetted. However standard lighting i useful as it doesn’t need as much memory to render compared to radiosity.

Photometric units

Photometry is the science of measurement of light. photometric units is the measurement to measure light. such measurements are lumens and candelas. They are used in the same way as we use liters or pounds. Lumens is the general measurement but candelas are specifically used in measurement concerning narrow beams of light.

Local & global illumination.

Local illumination – or shaders when using 3d max terms describe how surfaces deal with lighting arrangements. The shaders determine if a surface will look like plastic, metal or wood, smooth or rough etc. In 3ds max if you use standard lighting, the light coming directly from the source is what is used to determine the shaders prediction of dealing with the light.

Global illumination – Shaders also work co-operatively with each other, a shader will detect if another object is blocking it and calculate accordingly what light it is still getting from the source and/or if the other object is emitting or reflecting light onto it. This process is called global illumination.


A algorithm is a definite list of well-defined mathematical instructions for completing a task.


Ray tracing is a mathematic approach on 3D rendering. visualisations of programmed scenes are produced using a technique which follows rays from the eye point outward, rather than originating at the light sources” – wikipedia.

in a realistic simulation of lighting over other rendering methods due to the mathematical processing reflections and shadows have became a natural and thus easy effect to produce where as in other rendering techniques shadows and lighting are difficult to produce.


The shortfalls of ray tracing is it’s performance, it treats every ray separately when rendering, due to this and the strain of processing each, it takes a bit of power and a bit of patience when rendering a scene with ray tracing.  It also  starts the rendering process anew each time. Also when using ray tracing, rendering is not photo realistic, the shadows tend to be an exact silhouette of the shape rather than light being blocked by an object. Using ray tracing can give a rendered scene a cartoon look about it.


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