Large Map created with Matrice 4 RTK

[jaja6009]

I got a chance to process a large dataset with the Matrice 4 E.
It did not disappoint!

Link to cloud map:

https://cloud.agisoft.com/shared/projects/e8d556ef-a06d-46d8-99b4-a4c3986701a4

Mission parameters

• GSD: 1.9 cm
• Altitude: 200 ft AGL
• Speed: 29 mph!!!
• Camera Settings: Default Matrice 4 E ( Auto, Fixed Aperture, Manual Auto Focus, ISO and Shutter Speed set by camera according to lighting conditions)
• Double Grid Flight with Custom 60 degree oblique
• 1885 images ( ~ 200 images were discarded as they captured water )
• Processed in Agisoft Metashape
• No Ground Control (No Control Points collected)
• RTK enabled NTRIP Base located ~ 19 km away
• RTK Datum: NAD 83 (2011) with ellipsoid elevations (meters)
• Agisoft Output: Datum-NAD 83 (2011), Projection-NJ State Plane US Survey Ft, Vertical Datum-NAVD 88 US Survey Ft, Geoid 18 (Using US NGS Geoid undulation tiff)
• All images were FIX
• 3 Batteries used
• Area mapped ~ 149 acres
• I used several rounds of Gradual Selection (Reconstruction Uncertainty, Projection Error and Reprojection error) to remove points. My workflow on this for the most part follows the USGS workflow that many use and is readily available in a free PDF.

I have mapped this area several times, that is why I did not use ground control. I can assess accuracy by comparing my point cloud to the previous point clouds which were assessed for accuracy from New Jersey Authoritative LiDAR data in Cloud Compare.

My take on the Matrice.

• The faster image acquisition was really noticeable on this mission due to its size. The 0.5 second image taking allowed the drone to fly at an amazing 29 mph for this mission.
• Pilot 2 worked flawlessly. I was able to launch the mission, land and change batteries and continue where the mission left off without any issue.
• It took ~ 1 hour to fly the mission which was broken down into two different Area Routes so I ended with a double grid final output.
• I used the Custom Oblique option turned on and a 60 degree gimbal angle to better capture the sides of structures and also to help eliminate the vertical offset you get when processing only nadir images.
• I had RTK FIX the entire time and it went FIX very quickly upon drone startup
• The colors of the images and the output data were superior to the Phantom 4 RTK which was previously used to map this airport
• The drone is a little bit harder to keep LOS than the Phantom 4 RTK, but easier than the Mavic 3 E
• The 4/3 CMOS sensor picks up more data per image at a given GSD. There is more detail to the outputs than the Phantom 4 RTK. I can see no discernable difference though to the Mavic 3 E which also has mapped this area.
• The low noise propellers are noticeably quieter than the standard propellers. This is a nice feature as it does not alarm people and draw a crowd.
• If you use the SDC cable with the DJI Power 1000 you can easily charge a battery within the time it takes to fly a battery down low. With the DJI Power 1000 you have an extremely fast charing capability. I did not assess how much percentage each Matrice 4 battery drains from the DJI Power 1000 though.

I will conduct a final accuracy assessment by using a terrestrial GNSS rover to collect several control points and reprocess the alignment in Agisoft, but when overlaying the point cloud in Cloud Compare and assessing the data against NJ State LiDAR and my previous efforts, the data is as tight as I would expect.

Overall I found this drone to be worth every penny. While I have access to a Mavic 3 Enterprise, I persoanlly do not own one. I own a Phantom 4 RTK and this drone is a nice upgrade over that package. If you already own a Mavic 3 E, unless you need the added zoom, AI, Active Track and Flight Hub 2 Remote Control, and other new abilities this drone may not be worth the upgrade.