9. Removing Unwanted Stuff - Cleaning up the mess

Discritization while rendering causes artifacts in the images in the form of jagged edges. This commonly called the staircase effect. These
artefacts are called aliasing. To make the images free of these we do Anti -Aliasing.

1. Anti-Aliasing -
   Anti-Aliasing is done by supersampling at each pixel using a grid with, stochastically jittered grid centers. The grid is centered at the pixel whose
   intensity is to be calculated. The pixel gets the average intensity of all the intensities computed at each grid center. As the grid size increases
   the image quality gets better (but the render time shoots up exponentially - all good things come at a price !! ). But after a certain threshold image
   quality ceases to change appreciably. Given below are some examples of anti-aliased images -
   

   No Anti-Aliasing

   Anti-Aliasing : 2x2 grid

   Anti-Aliasing : 4x4 grid

   
   
   
2. Sampling -
   Currently all the grid points are given equal weightage while calculating the average at the pixel centre. Maybe a Gaussian weighting is a better idea.
   
   
   
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   Page last updated on 04 October, 2005.	AT cse.iitd.ac.in	© Parag Chaudhuri , 2009