Stefan Röttger

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Advanced approach:

Determine iso line on a pixel based grid:

• Interprete the scalar grid values as height values, forming a height field
• Compute the footprint area of the iso line of thickness one pixel by projecting the iso line onto the grid base
• projected range depends on the gradient of the scalar function (the slope of the height field)
• Calculate overlap of iso line foot print with the area of each pixel

Without line anti-aliasing:

• If overlap is more than 50%, color the pixel black, else white
• Results in about 1 pixel line size
• But also results in “jaggies”

With line anti-aliasing:

• Overlap ratio determines the color of the pixel
• Overlap ratio matches the anti-aliased pixel color of each fragment of the iso line
• Results in anti-aliased but “somewhat blurred gray-scale line”
• Double footprint size to 2 pixel to account for blurring (1 pixel core size, and half pixel border size)

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