Shader Portfolio – Unbiased Vs. Biased Rendering

Biased Vs Unbiased Rendering

Biased: Gives the user complete control over how the renderer interprets the scene. This means calculations for Spectacularity, Global illumination, Final gather, Shadows etc. have to be manually entered by the user and are a result of how the user feels the lighting interacts with the objects within the scene. This doesn’t always mean that the users interpretation of how the light interacts is physically correct, this can take a lot of finessing and if not done in the correct order, can quickly look “wrong”. Renderers such as Mental Ray, Vray and Renderman are known as biased renderers.

Unbiased: Is the opposite of a Biased, meaning that the renderer is in control of calculations. By doing it this way the renderer can create physically correct renders with minimal work for the user, who is in control of noise clean up and the amount of bounces in Diffuse and Refraction. This offers more control and less room for error with calculations. Renderers such as Arnold are unbiased and are increasing in use within the film industry due to their speed and render quality.

The pro’s and con’s of each render type can be broken down;

Pro’s; More control, faster render speeds, ability to choose quality of work also the user can predict possible render times, render times can go from seconds to minutes depending on global illumination and final gather photons as well as light quality and the amount of objects within the scene, better for use with hard caustics.
Con’s; Less ability to achieve realism and this isn’t dependent on how much quality the render has, but how the render handles information. However it can still produce quality renders.

Pro’s; Physically correct, realistic, less work for the user meaning some adjustments regarding camera and scene clean up and real time updates using the IPR render option, better at soft caustics.
Con’s; The render is never actually done, render times can be unpredictable and the overall quality cannot be chosen.




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