किसी नदी, खाई या किसी ऐसी बाधा के पार तलमापन (levelling) की प्रक्रिया, जिसमें दो बिंदुओं के बीच लंबी दृष्टि (long sight) की आवश्यकता होती है, कहलाती है:

In survey work using a total station with reflector measurements, which of the following sequence of temporary adjustments must be performed at a station?

While carrying out a total station survey on one bank of a 250 m wide river, it is necessary to plot electric transmission posts on the opposite bank. No provision exists for crossing the river and the posts are inaccessible. In which mode should the survey work be done?