How to use DJI Phantom 4 Multispectral (in-field video tutorial)

Community Input:

  1. Have you tested this workflow?
  2. What works?
  3. Other suggestions?
2 Likes

Hi Nathan,

Thank you for this great video that explains every steps involved in the process of generating orthomosaic maps.

I was wondering how critical the calibration images are. I do not own a calibration panel as it did not come with the drone. I never calibrated my images in 2021 and I was wondering if I should try to buy a calibration panel to ensure consistent maps for my 2022 season. I had in mind that since the drone has a Integrated Spectral Sunlight Sensor, the calibration was not necessary, am I wrong with that thought?

Cheers,
William

Additionally,

Do we need to change our course angle every time we go into the field? I saw that when I adjust the course angle to what is optimal, the orthomosaic map comes out with weird pattern as the course was oblique to the field, whereas when I keep the course angle parallel to the field, I don’t get these weird pattern in my orthomosaic map.

Thank you for your help!

After a fait bit of reading, I would like to use the MicaSense Calibration Reflectance Panel to perform calibration. Do you know if we can use this panel with a Phantom 4 multispectral directly within Pix4dFields? From my readings, it seems that the MicaSense Panel can only work with the Parrot Sequoia and would need additional information to work with a Phantom 4 Multispectral as the red, red-edge and NIR wavelengths are not the same between the Sequoia and the P4M. Is that still the case and if so, how can I find these values without having a spectro-radiometer with me?

Thanks for your help!

Hi William,

Great questions.

The calibration target is not necessary, however it does provide a stable reference/standard by which our software can calibrate the data on that particular day in your specific area. The integrated sunlight sensor provides important data about the sunlight. However, without very detailed internal calibrations it is very difficult for most cameras to be 100% targetless workflow. This is why many leading sensors include one.

On your second question, course angle changing is something DJI has implemented. It is said to improve the performance of the light sensor itself, providing a better view of the sun above. If you are getting a strange pattern that may be an impact related to pixel size and row width. I would suggest using the new blending option in version 1.11 which may solve that problem. Another tool now is Accurate Processing in 1.11, often times it can correct issues with DJI Phantom 4 Multispectrals when flights are performed at a high speed.

Thirdly, if you want to use a MicaSense calibration panel for the Phantom 4 Multispectral you can. It is fully characterized for each band and works well. The Sequoia panel only works for a Sequoia as it was only characterized for it. Another target which works - the one which I use in the video - is from Sentera and it also works well. We do not sell them and you would need to contact these vendors or dealers separately.

Thanks for your questions.

  • Nathan

Hi Nathan,

Thank you for your quick response!

So if I understand correctly, if I want to calibrate my Phantom 4 Multispectral camera, the Sequoia panel wouldn’t work with the multispectral camera included on my P4M. As for the Sentera calibration panel, it seems impossible to find one online unfortunately. I will continue my search, hoping to find a retailer that has one!

Cheers,
William

UPDATE TO VIDEO: DJI has recommended to use a specific speed of microSD to improve the performance. Specifically: use the SanDisk Extreme Pro A2 V30 microSDXC UHS-I for internal daily flight. However in the end users can use any microSD card with V30 speed standard.

2 Likes

Buenas tardes Nathan.
Me podrías indicar cuáles son los parámetros de calibración de la cámara del P4M para aplicarlos en el pix4dfield?
Muchas gracias.

Hello David, PIX4Dfields will automatically perform the calibration process based on the available information on the EXIF of the raw images and also with reflectance panel images if it is provided. You don’t need to insert the calibration parameters in PIX4Dfields. PIX4Dfields will automatically detect the camera using the metadata of the raw image and use those values. For more information, visit