Dioptra™- a camera position and angle measurement tool for navigation, surveying, positioning, and measurement. Celebrating 30,000 users in 2016! Instructions: Press the on-screen camera button to save an image. View saved images in your device's gallery app. [⊹] Dioptra™ provides the following information like a theodolite optical instrument - • yaw indicator (compass) • pitch indicator (tilt degrees) • roll indicator (tilt degrees) along with - • GPS position • azimuth and bearing to photo subject The ancient greek "dioptra" was a classical astronomical and surveying instrument, dating from the 3rd century BCE. The dioptra was a sighting tube or, alternatively, a rod with a sight at both ends, attached to a stand. If fitted with protractors, it could be used to measure angles. [⊹]