# Survey 5

## Triangulation

The aim is to use triangulation to locate unknown points.

Triangulation splits **network of** control points into system of adjacent
**triangles. Angles within triangles are measured and one distance is measured.**
This distance is called *base*. Then all the distances can be computed
and coordinates can be evaluated.

But in such case—there is no—or only a limited check for errors thus also distance of
**check base** is measured. Check base is located on other side of the
network.

### The equipment

Use total station to read horizontal angles and to determine the lengths of bases.

### Important notes

- Use a plumb bob to establish setup over the stations.
- Use a plumb bob (at the targets) when you point the telescope toward the stations.

### Evaluation

Evaluate the angles and distances from values measured accordingly. If you choose the overdetermined system of triangles (picture 3 from above), then use

- software for geodetic engineers (LISCAD by Leica), which provides module
*Adjustment*(least square adjustment of field data) or - split the network into two solutions (picture below) and interpolate between them to find the best fit.

Finally transform coordinates of stations into local coordinate system where A = (0,0) and azimuth AD = 90°. That can be done easily in CAD and is going to be useful to compare the results between the teams.