lecture17 - CSE472 Computer Graphics Radiosity What can we...

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1 CSE472 Computer Graphics Radiosity What can we do with scan line conversion and ray tracing What we can’t do Radiosity
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2 CSE472 Computer Graphics Types of Illumination Scan-line Techniques Diffuse reflection of light sources Specular reflection of light sources Ray tracing and move advanced scan line techniques Specular reflection from other objects Transmission Seem like anything is missing, here?
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3 CSE472 Computer Graphics The Big Lie!!! Ambient Light! Does not really exist It’s faking light reflecting from other surfaces
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4 CSE472 Computer Graphics What really happens Light reflects off of surfaces and illuminates other surfaces Every surface affects every other surface One hacky solution Assume all of the light from all surfaces is averaged into a single illumination lighting that goes everywhere That’s what we’ve been calling ambient light.
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5 CSE472 Computer Graphics Ambient Light is an approximation Many elements of natural lighting are not modeled well by ambient lighting at all Corners Interiors Moving items
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6 CSE472 Computer Graphics Characteristics of Diffuse Reflection How will OpenGL draw this box? What about ray tracing? What about nature? Light Box
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7 CSE472 Computer Graphics Our box on edge
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8 CSE472 Computer Graphics Complex Lighting Environments This is really a complicated lighting  environment.   There is specular and diffuse reflection  everywhere  in the box.    Ray tracing can approximate the specular  reflection fairly well, but not the diffuse  reflection.   Let’s just look at diffuse reflection for now. Note:  In the real world diffuse and specular  reflection interact in a complex manner.  We’ll  get to combining the two later.
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9 CSE472 Computer Graphics Radiosity Fundamental principle: Conservation of energy Light is either absorbed or reflected!
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10 CSE472 Computer Graphics Radiosity Every  surface is treated as a diffuse reflector  and  emitter  and all surfaces are assumed to conserve  light energy.   The rate at which energy leaves the surface, the  radiosity is the sum of the rates at which the surface reflects or  transmits energy from other surfaces and the rate at  which the surface emits energy.   Note:  we no longer have disjoint light sources.  Every object in the space is treated the same.   A light source is simply a surface that emits energy.
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CSE472 Computer Graphics How do we solve this? Simple example:
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lecture17 - CSE472 Computer Graphics Radiosity What can we...

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