> oversampling, but oversampling of what exactly? If you have 3 million pixels of sky, and 3 variables to find, then you have oversampled by 1 million times.

> oversampling, but oversampling of what exactly? If you have 3 million pixels of sky, and 3 variables to find, then you have oversampled by 1 million times. In the ideal noise-free world with no other unknowns, any 3 of those pixels would be enough to solve the problem perfectly.