Overview

Whether you are working with satellite, aerial or LiDAR imagery, Ground Contol Points (GCPs) ensure that your project contains “Ground Truth” – the data is tied to a specific, human-verified location on earth.  For example, using Quality-1 GCPs in the orthorectification process results in increased accuracy (sub-meter) and the quality of our orthoimagery. Each of our GCPs is provided to the customer with all supporting metadata, context photos, accuracy reports and station diagrams.  Increase accuracy and save time and money.

Accuracy Levels
The GCPs in the CompassData archive have all passed rigorous quality-control procedures. The accuracy of the GCPs are defined as follows.

• Quality-1: 1cm – 10cm horizontal accuracy, 3cm – 10cm vertical accuracy
• Quality-2: 10cm – 20cm horizontal accuracy, 10cm – 20cm vertical accuracy
• Quality-3: 20cm – 50cm horizontal accuracy, 20cm – 75cm vertical accuracy
• Quality-4: 50cm – 70cm horizontal accuracy, 75cm – 1.25m vertical accuracy
• Quality-5: 70cm – 2.5m horizontal accuracy, 1.25m – 5m vertical accuracy