A table tennis ball is all white. When struck there is a high probability that a spin will be induced. This spin direction is hard to distinguish.

This idea would paint/ink two filled Triangles at the poles pointing a direction as on an imaginary X Y circle. and, offset up and down, from the X Z equator are two broken lines of smaller triangles both pointing the same way.

These markings should give an distinct pattern change depending on the spin vector applied. Looking at either pole gives a circular ring of rotating arrows, forward or backwards. Looking side on at equator gives two lines of arrows forward and backwards. The third plane view gives the pole triangles making an equator line.interspersed with moving double triangle lines. Any other spin is a composite from these three.

Simple, easy but a bit not halfbaked.What would be good, is a surface tessellation and ink shape that when spun shows a animated flashing arrow. No obscure Moire patterns that I need to know?
-- wjt, May 30 2021

I tried the two hemispheres, but it didn't contrast enough over a range of playing strokes. small filled circles and triangles worked better.

After a discussion with a friend, I did have the idea of a light reference grid/pattern that could be shined centrally down onto the table . This could be as simple as a light bulb with painted densely with lines. The ball could have another tessellated pattern. The motion of the ball would interfere the patterns giving a sense of spin direction and speed. Hopefully.
-- wjt, Jun 05 2021



random, halfbakery