Every map, model or engineering plan relies on known points on the ground. When those points are reliable and tied together, all deliverables "sit" on each other. When they are not, discrepancies appear — usually at construction stage, when fixing them is expensive.
What is a control network?
A set of fixed points whose coordinates were measured and computed with high accuracy and linked to the national reference system.
Principles of a correct set-up
- Plan the placement so points are stable, accessible and cover the whole project area.
- Measure with methods and equipment suited to the required accuracy, including repeat measurements for control.
- Adjust the network and tie it to the national network.
- Fully document and protect the points throughout the life of the project.
Control networks and aerial mapping
Even in aerial mapping and LiDAR projects, ground control points anchor the deliverables in space and allow their accuracy to be verified.