A traditional surveying instrument consisting of a straightedge equipped with a sighting device, such as a telescope or peep sights. It is placed on a plane table and aligned with a target to draw lines of sight directly onto a map. While largely replaced by total stations, it remains a fundamental tool for manual topographic mapping.
Heard on the job
Set up the plane table and use the alidade to shoot the corners of that building so we can sketch it in.
Insider tip
When using a telescopic alidade, always check the level bubble on the straightedge before drawing your line.