The stereometer eliminates all guesswork previously associated with height
readings and greatly speeds up accurate aerial mapping.
The Stereometer has an effective measuring range of 40mm and minimum drum
graduations of 0.05mm, while infra-red readings of 0.01mm are also possible,
with experience.
Three stereomarks (zero, dot and plus) are engraved on the Stereometer glass
plate to suit the landmark being used.