Coloured Lights , Multiple Lights, Ambient Light

• To get coloured lights, we perform lighting calculation three times to get an RGB triple.
• More correct to use wavelength, and better approximations to wavelength exist, but RGB sufficient for now
• To get multiple lights, compute contribution independently and sum:

  

• Question: what do pictures with this illumination look like?

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Ambient Light:

  

• Lighting model is harsh
• Problem is that only direct illumination is modeled
• Global illumination techniques (radiosity) address this but are expensive
• Ambient illumination is a simple approximation to this
• Assume everything gets uniform illumination in addition to lights