It's not clear where the origin of the concentric circles are, besides a brief mention of a series of centered concentric dotted circles. Which is centered around what?

It's probably be helpful to add a rectangular border to the embedded image to signify the screen.

Width and height are expected to be inclusive, but then the addressable range would be 1 bigger than the actual width: 0-2000 has 2001 values, not 2000.

The reference solution appears to be generating 1001 points when pointNum is 1000.