ENDS%20375

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ENDS 375

• Foundations of Visualization
• 11/30/04 Notes

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Image Synthesis

• Aliasing
• Anti-Aliasing

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Aliasing

• Basically an under sampling problem (for point
  sampling)
• Example artifacts
• jagged edges
• pixel scintillations

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Nyquist Sampling Theorem

• Point sample at a rate at least twice that of
  the highest signal frequency
• Either
• increase sampling rate OR
• decrease signal frequency

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Decreasing Scene Frequency

• Low pass filter environment
• area sampling
• convolution
• ideal filter kernel - sin x/x

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Increase sampling rate

• super sampling
• average the super samples for each pixel
• stochastic super sampling
• shifts aliasing artifacts into visual noise