Abstract: Alignment of a 2D image to a corresponding 3D image is provided by writing a pattern into a 3D sample. The pattern is at known positions in the 3D image, and provides visible reference features in the 2D image. This permits accurate determination of the plane in the 3D image that corresponds to the 2D image.

Abstract: An optical system for providing a viewer with contrast between a golf ball and its environment, including a light filter and at least one polarizer mounted in a viewing device. The light filter has no more than about 20% transmittance of light in one of the range of wavelengths of from about 500 nm to about 700 nm. The viewing device allows for the light filter and the polarizer to be arranged in front of at least one eye of the viewer. The optical system can be provided in a spotting scope, a pair of eyeglasses or an attachment to eyeglasses for ease of use.