Definition
An aerial photography system that uses three cameras mounted in a fixed arrangement to capture a continuous strip of imagery from horizon to horizon. One camera points straight down at the ground, while the other two are angled outward to the left and right, so the three overlapping images together cover everything from one horizon, across the ground directly below, to the opposite horizon.
Plain English
A way of taking aerial photos using three cameras at once -- one looking down and two looking sideways -- so a single pass captures the full width of ground from one horizon to the other.
Context Anchor
Seen in aerial survey, mapping, and older chart-making discussions, especially where aircraft are used to photograph large areas of terrain.
Derivation
From 'tri-' (Latin for three) and 'metrogon,' the brand name of the wide-angle lens originally used in this system. The name simply tells you it's a three-camera setup using Metrogon lenses.
Why Pilots Care
Pilots flying photo or mapping missions need to understand the camera arrangement because flight planning -- altitude, ground speed, and track spacing -- is built around the coverage pattern the cameras produce.
Intuition Check
Do not read this as just “three measurements.” In aviation mapping, Trimetrogon means a three-camera photo setup used from an aircraft.
Example Sentence 1
The mapping flight used a trimetrogon camera system to photograph the entire valley in a single pass.
Example Sentence 2
Updated sectional charts were produced from trimetrogon images taken during the survey mission.