Hey All,
I’m in the processes of creating a ‘how to’ document for our drone program at work and want to make sure that I am understanding the correct workflow with the RS2+ as a base and rover with the NRCAN PPP corrections. I have read endlessly through the great documentation that is provided by Emlid and have come out a little overwhelmed and still confused. I am trying to create a workflow that is going to introduce the least amount of error as possible.
We will be flying the DJI L2 LiDAR sensor and need to collect both base data to feed into DJI Terra, and GCP’s for imagery. We would use the same process for other sensors and imagery as well. RTK is not a possibility for most of our projects.
I have a firm grasp of the PPP process through NRCAN, but don’t know what initial settings are the best for both the base and rover. On the base how long should I be averaging a point and should I be using single, fix, or float? Likewise, do I need to average that value and then set that as the base coordinates, or does the unit do that itself after the averaging time?
For the Rover, again, do I set it to single, float, or fix and what is the recommended averaging time to collect Ground Control and Check points? I am also wondering if my Base and Rover need to be set to the same coordinate system somehow, or if Emlid Studio is able to apply the corrections to the rover no matter what CRS the points are collected in.
I appreciate any help!
Hi @kevan.freeland,
Welcome to the community!
To clarify, are you planning to use PPK for the entire workflow? And are you working with two Reach receivers, one as a base and the other as a rover? That would mean your GCPs will also be post-processed, correct?
How are you planning to approach this? Would you prefer to collect all the data first and post-process everything afterward, or obtain accurate base coordinates via NRCAN first and return to the field another day for GCP collection?
If everything is done with PPK, there’s no need to establish an RTK link between the base and the rover. Here’s a suggested workflow:
Field
- Set up your base on an unknown point and log data for at least 4 hours.
- Place your GCP markers on-site.
- Since a direct link between the base and the rover is not required for PPK, you can collect GCPs in Single (standalone) mode. I recommend averaging each point for at least 5 seconds.
Office
- Upload your base RINEX logs to NRCAN to get precise coordinates.
- Post-process your CSV using Stop & Go, using the base coordinates from NRCAN.
- This will give you a corrected CSV with global coordinates.
- In Emlid Flow, create a project using your target coordinate system.
- Import the corrected CSV. Flow will automatically reproject the coordinates.
- In Terra, use the same coordinates you got from NRCAN.
Hey Ruth,
Thanks for replying, we have two RS2+ heads, these will act as a stationary base and a rover for GCP’s. Initially we intend to do everything on the same day using PPK. Eventually we may want to do repeat data collection or drop new GCP’s, or re-fly an area using RTK and the known coordinates of the base.
The process you outlined is essentially what I was expecting.
- Does it matter what projection I set my Emlid Flow Project to?
- Will the stop & Go processing in Emlid Studio always produce global coordinates?
We generally work in NAD83 BC Albers, but it’s not a huge deal to work with this data in another CRS.
- Does it matter what projection I set my Emlid Flow Project to?
Before PPK, no, it doesn’t matter. The Stop and Go in Emlid Studio takes the averaging start and end from the CSV and interpolates it with the time from the .pos file generated during kinematic processing.
- Will the stop & Go processing in Emlid Studio always produce global coordinates?
Yes, the results will always be global. Following this guide, you can obtain projected coordinates after Stop and Go PPK.
