January 2, 2010 Advanced Technoligies: Scan Conversion

January 2, 2010

   Scan Conversion and Interpolation 

The Scan Conversion is to take the filtered RF vector line data and put it 
into a presentable form for display. It converts the polar coordinates to 
rectangular pixel positions. Normally interpolation is done at the same 
time during conversion.

An enlargement of the polar coordinate scan lines overlaid on the raster 
rectangular pixel grid indicates the problem. Not only do the scan lines 
rarely intersect the pixel locations, but also each spatial position in the 
sector presents a different interpolation because the vectors change 
angle and are closer toward the apex of the sector. Early attempts at 
interpolation caused severe artifacts, such as Moire's pattern, and 
unnatural steps and blocks in the image.

New approach has been developed for a fast 2D interpolation and 
conversion for a better image quality.