Now, let�s move on to total stations -
A total station is an electronic/optical instrument used
in modern surveying and building construction that uses electronic transit theodolite in conjunction with
an electronic distance meter (EDM).
It is also integrated with microprocessor, electronic data collector and storage system.
The instrument is used to measure sloping distance of objects to the instrument, horizontal
angles and vertical angles.
The Microprocessor unit enables for computation of data collected to further calculate the horizontal
distance, coordinates of a point and reduced level of a point.
It is its ability of capturing the coordinates of a point that is of interest to us.
This is done by first establishing the coordinates of one base station at the site.
This could be done using one of the GPS systems of capture described previously.
Coordinates of an unknown point relative to a known coordinate can be determined using the total station as long as a direct
line of sight can be established between the two points.
With total stations, obstructions like trees and buildings don�t affect the data capture process as long
as there is direct line of sight.
Each relative point measured can reach millimeters of with
respect to the base station (depending on the distance of the measured points from the station).
Now, let us compare the utility of GPS systems versus total stations... GCP capture with GPS systems is a lot
faster than using Total stations.
This is because the radio communication is instant and doesn�t require any elaborate manual observation
as is needed with Total stations.
Also, there is no need of line of sight between the base station and the rover.
However, in sites which have too many obstructions, it�s best to use a total station based GCP capture
as long as the base station is set up accurately.