So, surveyors can use combinations of the following devices to achieve desired levels of accuracy: PPK technique is used as a supporting data source to the RTK method to boost the precision of the acquired data. PPK stands for post-processing kinematic, and the term suggests post-processing techniques complement the coordinates data after collecting the imagery. The second way to ensure positional accuracy is to use PPK. This type of coordinate acquisition allows constant rectification/amendment of coordinate data to maintain positional accuracy.ĭJI Phantom 4 RTK with D-RTK 2 GNSS mobile station In cases of high-end equipment, the coordinates may be as accurate as 1 cm in value. RTK devices provide satellite GPS corrections using ground base stations as reference. RTK is an abbreviation for the Real-Time Kinematic.
Ground control points professional#
Ground control points are defined using professional georeferencing equipment, e.g., RTK capable devices. Any key point on the reconstructed 3D model or mesh may be used as a georeferencing point and linked with the separately provided coordinates. It is necessary to have at least 3 GCP points on a target object for an acceptable result. GCPs are acquired using professional, survey-grade georeferencing devices. GCPs are widely used when processing photogrammetric image sets. The GCPs are used for accurate georeferencing to indicate coordinates of a point on the surveyed surface, thus resulting in the most lifelike 3D model in the end. Usually, a surveyor places a black-and-white checked mat or any bright object to state the ground control point. GCP is a mark on the target surface linked with a known precise geographical coordinate point.
With sleek coloring, well-laid shading, and realistic 3D modeling in photogrammetry, GCPs are the tool used to bring the photogrammetric project to a precise absolute position and scale. Ground control points (aka GCPs) are the cornerstone that makes the highest accuracy mapping possible.
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