PPK on offshore platform

Hi there,

Does anyone have experience with using the Reach RS+ and Reach M+ hardware on an offshore platform? Soon we have a job which is mapping an offshore platform at 30km off the coast in the sea and we wanted to use the Reach PPK setup for accurate photo positions however we do think that the platform is moving due to waves of the sea.

I was thinking of using two Reach RS+ systems set up as base and afterwards processing the logs in RTKLib however I do not have any experience regarding the moving base etc. Does any of you have experience with it or have suggestions on how to do this properly?

Regarding my last (and first :slight_smile: ) post, We have found the solution of the strange shift. It was calibrating the camera in PiX4D after that the results were fine :wink:

Kind regards,


Do you need absolute or relative precision?
What RMS error can you tolerate?

You could setup your base at shore. 30 km L1 baseline is doable, but only if both base and rover have excellent SNR.

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I think that @ldegraaf is wanting to do photogrammetry on a moving vessel (offshore platform) that is probably chained to the seabed but still is subject to movements from wave action.

The the first question seems to be that since the subject will be moving while the photos are being taken, is the assumption correct that the processing should be done in moving base mode?

The second question seems to be will there be benefit to operation of 2 RS+ bases with 1 M+ rover? I’ll add to it: If so, then should the 2 bases be placed on opposite sides of the vessel, or should one base be placed on land and one on the vessel? What will the benefits be?

I would definitely use laser scanner it this scenario and forget photogrammetry

@wizprod What I need in the best situation is an absolute position as accurate as possible. regarding the RMS error as low as we can get :sweat_smile:

@bide Thats absolutely correct! But its not a vessel. It is a stationary platform but I do not know if there is any movement in the platform due to the waves. I am curious if operating two base modules would be the correct way and if so how should it be post processed.

@Kansanparantaja, thanks for the suggestion! that would be a viable solution. However, the customer wants to run the pictures through some sort of algorithm/machine learning program to detect rust. Of course it would be nice to also generate a 3d model out of it, but I think it will be real pain with all that water and sky in the background. By the way, is there anyone who has a solution to batch process all the images to mask the water/sky in the background? :sweat_smile:

Hi Lammert,

At the moment, moving base is not officially supported in ReachView.

Just as Christian proposed, you can place the base at shore for PPK workflow. Reach RS+ units work just fine with the baseline in 30-40 km.

I used to work offshore. If you are talking about an anchored floating unit, forget precise positioning : that is completely useless as your antenna will constantly move by several metres. Then, the photogrammetry can be done RELATIVELY to the moving structure, I mean the software will adapt a local coordinate linked to the structure and will position pictures against it. That should work. You will need a known baseline on the structure (dx, dy, dz) to put a scale on your model. A bit of land survey operation is needed here.
If it is a platform, with feet firmly standing in the seabed, then no noticeable move and you can observe a vector from shore. But 30 km is at the limit of L1 only receivers. If it is a work for oil industry, you can afford a RS2 !


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