principal vertical

Related to principal vertical: prime vertical circle

principal vertical

On an oblique photograph, a line perpendicular to the true horizon and passing through the principal point.
Dictionary of Military and Associated Terms. US Department of Defense 2005.
Mentioned in ?
References in periodicals archive ?
With the posts or staves getting farther and farther apart horizontal clapboards or weatherboards needed intermediate support between these principal vertical load bearing members.

Full browser ?