We don't have synonyms for backsight yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are jacklight, backlight and blacklight.
(n) :
(surveying) A measurement or reading taken back towards a point of known elevation, used to calculate the height of the surveying instrument (theodolite, transit, total station).
(n) :
(surveying) A measurement of a previously shot point, used to set the angle to zero when occupying a new position.
(n) :
(surveying) A measurement or reading taken back towards a point of known elevation, used to calculate the height of the surveying instrument (theodolite, transit, total station).
(n) :
(surveying) A measurement of a previously shot point, used to set the angle to zero when occupying a new position.