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Advanced lighting and rendering. Multipass rendering. Outline. Introduction What is it? Advantages and disadvantages Multipass rendering in Maya Some examples. Introduction. Previously we have looked at many different types of lighting and rendering
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Advanced lighting and rendering Multipass rendering
Outline • Introduction • What is it? • Advantages and disadvantages • Multipass rendering in Maya • Some examples
Introduction • Previously we have looked at many different types of lighting and rendering • These can produce highly realistic results • There are occasions when we need special effects or more subtle control over what we produce • This lecture looks at one technique for this: multipass rendering
Multipass rendering • When we render a scene, there are many components that combine to produce the final rendered image • Multiple light sources • Multiple objects (each of which may reflect light back into the scene) • Each surface has multiple components (diffuse, specular, reflective, etc.) • There will often be occasions when you need to alter one or more of these components after the render • This will normally require re-rendering the entire scene • We can avoid this is with multipass rendering
Multipass rendering • Basically this involves rendering one or more components of the pixel values that make up your finished image to separate images • These images can then be combined to make a single image using compositing techniques (e.g. in Photoshop for a still or After Effects for a video) • By changing the way in which these components are combined we can alter their effect on the final image without re-rendering the entire scene • For complex scenes this can save a lot of time
Simple example • Consider a scene with classic 3-point lighting (key, fill and rim) • We can render the effect of each of these lights to separate images • We can then combine these to give the desire value to each light
More advanced MP rendering • So far we have just changed light parameters to create our multipass renders • There is more we can do to add even greater control by adjusting surface parameters and render options • Consider an example…
Types of passes • Typically there are a number of passes that will be used: • Beauty pass • Diffuse pass • Highlight (or specular) pass • Reflection pass • Shadow pass • You may use some or multiple versions of each pass in the finished result
Summary • Introduced multipass rendering • Discussed why it’s useful • Looked at some examples