Using a total station for surveying or machine control gives us a tool to measure with a high precision. But before we start working we need to setup the station, in other words we need to tell the station where it is on the jobsite. This is necessary because the measurement between the station and the target is always relative. That is, we only measure the coordinates of the prism in relation to the position of the station. There are various ways to setup a station. In the following two sections we will describe the two most common ways. However, regardless of what method is applied on the jobsite, we will always need to level the instrument first.
In this method we use either an optical plummet or a laser plummet to place the total station exactly over a known point. It is important to consider the height of the instrument over the point, after entering the coordinates as well as the height of the station we need to set the orientation. The orientation is the adaption of the internal orientation to the orientation of the local coordinate system.
|Measure height to the Known Point||Random Orientation of the Total Station|
|Adjusting the Orientation of the Total Station to fit to the jobsite system||Adjusting the Orientation of the Total Station to fit to the jobsite system|
When using the resection we do not need to setup the station over a known point. Instead we can setup the station at a point that is best suited for the current task. After levelling the instrument, we then measure to at least two points with known coordinates. The given coordinates of the points enables us to calculate the position and the orientation of the station. Using more than two points gives us further possibilities to reduce errors caused e.g. by errors in the fixpoints.