[Greg McKaskle]

The code this year is a bit smarter. It is also covered in the white paper. It uses something called the Equivalent Rectangle for a particle.

Basically, a particle has an area A and a perimeter P, so you can solve for the rectangle of height H and width W where A=H*W and P=2*H + 2*W. It can do this for circular, trapezoidal, and other shapes, and doesn't really claim that the particle is a rectangle, but if it happens to be, the W and H should be pretty close, typically a tighter fit than the bounding rect and less sensitive to skewed rectangles.

This year's example uses both the bounding box and equivalent rect as measures to compute the distance.

Greg McKaskle