Master thesis presentation: Evaluating need of cleaning using drone

Lisa Wennerlund will present her master thesis;

“Evaluating the need of cleaning using 3D point clouds derived from high resolution images collected with a drone”

On Thursday the 8th of March at 15.00 in Ljungberglabbet.

Supervisor is Jonas Bohlin and co-supervisor is Jonas Jonzén. Håkan Olson is the examiner.




Open lab every Wednesday

We now have “open lab” every Wednesday afternoon (13.00-16.00). At this time you can explore remote sensing data, use the lab’s sensors to collect data or follow one of our tutorials to learn how to work with remote sensing data. The tutorials is an ongoing work and will be published on the website as soon as they are ready for you. You can also ask questions to the lab’s forest remote sensing experts.

We also have a HTC Vive (Virtual Reality) that can be used to explore point clouds from mobile laser scanning, terresterial laser scanning and drone data.

Henrik visiting a forest in Virtual Reality.



Quick Camera test: DJI Phantom 4 pro vs Mavic pro

Here are some quick results from the drone camera tests we did two days ago. We flow four different cameras under similar conditions. The data set should ideally be used buy a student to do some project and a deeper evaluation of the cameras. But as we know that many in the forest industri are thinking about the difference between the Dji Phantom 4pro camera with a global shutter and a larger sensor compared to the Dji Mavic pro which is smaller, cheeper and has a, for photogrammetry, poorer camera.

The drones (and cameras) was flown in the evening with low sun behind thin clouds, generating no shadows but also not bright light. This lighting condition should push the cameras a bit and at the same time give less problem with bright sunlit tree crowns against a dark shadowed ground.

A orthophoto was made in Pix4D cloud service using default settings. Here are the results:

The Phantom 4 pro camera (on the left) has a higher dynamic range in the spectral resolution and is also less over exposed on the road compared with the Mavic pro (right image).

For the final test the Sony a5100 and the Parrot sequoia needs to be added and the images needs to be compared in more depth as well as their performance when generating point clouds.



Three drone systems, four different cameras

We decided to take our drones to the forest and test some cameras today. We flow two 3DR Solo; one with Parrot Sequoia and one with a new Escadrone SoloMapper (Sony QX1 camera) and two DJI drones; one Phantom 4 pro and one Mavic pro. This was done because we had a great opportunity to acquire data from four forest patches that has just been scanned with a good terrestrial laser scanner. The scans was multi-scans with 16 scans in a 8 x 2 grid. The point cloud from the laser could be used for evaluating the point clouds generated from the drone cameras.

We tried to fly slow (5 m/s) and with lots of overlap (90/90). Sadly we ran in to trouble with the new SoloMapper, it did not acquire more then 15 images and then the system stopped. This was the first time ever we tested the camera system on the drone so it was probably a installation error of ours. We switch camera to a Sony a5100 that we have used before but which doesn’t have a gimbal, so we got good quality images.

This data set, with four different cameras, would be perfect for some student to use for a project or thesis.