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.