GCPs: RS2 unit on the ground?

In the case of GCPs for processing UAS mosaics, and to make sure we collect the very center of the GCP targets, is it advisable to place the RS2 unit directly on the GCP (ground level) instead of using a pole?
Is there a document of best practices for GCP collection with GNSS systems and/or with emlid products in particular?

If the pole vial is calibrated there is no need to do such thing.
It is not advisable to put the receiver directly to the ground due to increased multipath effect.


Hi Agustin,

We have a detailed video guide on how to place ground control points (GCPs) with Reach RS2. It’s available on our channel on YouTube, you can watch it here. The text version of it is in our Placing GCPs in RTK mode guide.

Please note that we don’t recommend placing the receiver on the ground as it reduces the signal quality and causes the unsatisfactory observational data quality.


Generally, from an SNR perspective, the more distance over ground the receiver has, the better. However, from a mechanical stand-point, it is the opposite. The more distance, the more a given angular error will influence. So, looking at it from a optimised point of view, the ARP should be higher than the people around it. Usually, if you have a 1.8 to 2 meter pole you are fine.
If you want to eliminate most of the uncertainty regarding levelling of the pole, then get 8 minute vial from i.e. Seco as an additional vial to the one they usually come with (which are usually 40 minute).


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