Community Forums

Share:

PPK results with Phantom 4 Pro v.2  

Page 1 / 4

leegreen
Posts: 1671
Member
(@leegreen)
1,000+ posts
Joined: 8 years ago

For the past month I have been working with Cody Remington founder at  BAAM Tech

They sell and install a $2500 PPK kit for any DJI Phantom 4 and Inspire 2. The system utilizes GPS L1/L2, GLONASS G1/G2, BeiDou B1/B2, Galileo E1/E5b and SBAS constellations. They include a software for post-processing the RINEX log files from your Survey grade base station and the log file from the sUAS system.

The process is very simple, here is a brief step by step;

  1. You set up your GNSS base receiver to log static data at 1-second epochs.
  2. Place the sUAS with PPK system on the center of the Iron Cross aerial target (supplied with the system from BAAM Tech). This stores the initial point of the PPK as your single calibration point.
  3. Launch your sUAS mission. The system triggers the camera to synchronize with the static log file. All static data is stored in the included USB drive on the system. The PPK receiver uses the drone power supply, so no additional charging.
  4. The Post-processing software from BAAM Tech computes the Lat/Lon/Ell and replaces the GeoTag for each photo of your aerial mission. 
  5. Mark only the launch point on 5 photos in Pix4d, and process.

Here is a snippet of accuracy report from Pix4d.

check points

Complete Pix4d report.

18 Replies
Avatar
Posts: 429
Member
(@chris-mills)
250+ posts
Joined: 7 years ago

Lee, it would be worthwhile repeating step 2 at the end of each flight as a check that all was well.

Reply
Avatar
Posts: 240
Member
(@andrewm)
100+ posts
Joined: 4 years ago

Lee, thanks for the information.  I'm definitely interested in this.  How long did your static run in the this project example?  If you didn't put out the other targets as checkpoints, you could complete this entire mission in way less than an hour.  Does the static need to run for a minimum amount of time to achieve these accuracies?

Reply
2 Replies
leegreen
Member
(@leegreen)
Joined: 8 years ago

1,000+ posts
Posts: 1671

Andrew,

The entire static was only 20 minutes, including the flight time.  If you contact BAAM Tech, please mention my name.

Reply
leegreen
Member
(@leegreen)
Joined: 8 years ago

1,000+ posts
Posts: 1671

If your not familiar with how PPK and Rapid Static can work together, I'll try to explain it here.

On a project you have never visited (which is the most common) you set up your base to collect 1-second epoch static data at an unknown location. Just set a nail, this does not have to be on a target. But it is a good idea to use an aerial target since it is an easy check. This base must collect at least 15 minutes of static to send it to OPUS-RS for an accurate SPC to be computed, not hard to do.
 
Turn on your drone, then you place it on a second aerial target, centering the camera on the target. The drone will automatically take a photo of the launch point while on the ground. This is only for calibration. The BAAM Tech system on the drone will also collect 1-second static data, and it will synchronize the clock with a much more accurate clock. The BAAM Tech system will accurately mark the exact time each photo is taken. The clock accuracy is one of the fundamental differences between mapping grade GPS and Survey grade GPS, along with added signals and frequencies. These clocks are accurate to the second of time, 8 places past the decimal. The SV's have atomic clocks which are even more accurate. So when an epoch of data is collected it is later post-processed to compare the exact epoch with other receivers. This is how the position is calculated. You will send your Base data to OPUS-RS for an accurate State Plane coordinate. Then use you will use BAAM Techs software to post process your Base data with the Drone static data, using the coordinate of the base computed by OPUS-RS.
 
As Chris Mills mentioned, you can also place the drone camera back over the launch point at the end of the flight mission and take a photo as a check.  In fact, you could even walk the drone over to other checkpoints, place the camera directly over the point and take a photo for more checks. When you take a photo, it records a static position, just like a rover and data collector would do. The BAAM Tech antenna height is an additional 0.04m from camera to the ground. The antenna height from the camera to the phase center is 0.208m. Essentially you are using the BAAM Tech system as your GPS rover pole. I prefer to use RTK that is part of my Base Rover system to do this. But if you have only one GPS receiver and use that as a Base, the BAAM Tech System can be your survey rover. The BAAM Tech system is removable and portable. You can move it to another drone, or you could place it on a GPS rover pole to collect check points.
Reply
Jered McGrath PLS
Posts: 1350
(@jered-mcgrath-pls)
1,000+ posts
Joined: 9 years ago

Great Post Lee, Thank you for sharing.

Reply
GMPLS
Posts: 332
Member
(@gmpls)
250+ posts
Joined: 5 years ago

Thanks for posting this Lee and once again it was good talking with you. I sent my P4P in today and am already anxiously awaiting its return.

Gregg

Reply
Page 1 / 4