Hiphen Blog - DJI Mavic 3M - A revolution for drone phenotyping?

Last time in the Hiphen blog we were talking about the evolution of drone equipment for agricultural applications, saying that it has become more and more accessible and easier to use through the last decade. Now we’ve reached a new milestone in drone phenotyping, as DJI released a new version of the Mavic range with the Mavic 3M, a promising device that embeds a high-resolution RGB camera combined to a large-specter multispectral camera, and at Hiphen we’ve already tested it. So, evolution or revolution?

1/ A Great Sensors Combination Making This New Mavic The King Of Its Category.

A 5MP multispectral camera (560nm > 860nm) combined to 20MP CMOS RGB camera will basically give you access to the most thought-after traits currently, from biochemical traits such as leaf surface to plant count and plot quality traits, you can now access all these measures easily within the same flight.

Figure 1: As we make our detection models evolve, we are now able to extract much more precise information than before.

Here is an example of images you can get with the new Mavic 3M; RGB + Multispectral images are acquired at the same time to speed up plant asssessment:

Figure 2: RGB image of Strawberries from Mavic 3M

Figure 3: NDVI of Strawberries computed from Mavic 3M

Figure 4: GNDVI of Strawberries computed from Mavic 3M

Figure 5: NDRE of Strawberries computed from Mavic 3M

2/ Comparison with its predecessor the DJI Phantom 4M

What as evolved a lot from the previous model from the DJI family, combining an RGB + MS camera, is actually the RGB camera. Indeed, the sensor combination of this new Mavic 3M is way better than the DJI Phantom 4 MS, RGB images being sharper, more balanced and more precise with the new CMOS 4/3 sensor thanks to its 20MP resolution (see example below)

Figure 6: RGB image from the Mavic 3M

Figure 7: RGB image from the Phantom 4M

Then the multispectral camera as not really evolved, the specs are almost the same, the slight difference is that the Near-infrared (NIR) filter of the sensor is now calibrated at 860nm vs 840nm on the Phantom 4M. In practice this doesn't change anything to assess the plant reflectance in order to extract NDVI, GNDVI or NDRE indices from your images.

Figure 3: NDVI of Strawberries computed from Mavic 3M

Figure 8: NDVI of Rapeseed computed from Phantom 4M

The blue band is no more included in the MS sensor of the Mavic 3M, indeed this band is not specifically useful in most applications, moreover we can still acces it with the RGB images containing the Red, Green & Blue wavebands.

With this great sensor’s combination, we can now combine RGB + Multispectral image acquisition at the same time, during the same flight, where before 2 separate flights were needed to acquire RGB and MS data. However, you will still need to upload your RGB and MS datasets in 2 different upload sessions to make sure processing will run smoothly.

This new drone also helps us envision merging the best of both worlds (RGB + MS) to dive into much more detailed granularity of information that we can extract from such images. We’ll continue testing and developing modules to access new traits in the future – stay tuned!

Figure 9: The cameras in action - You can now choose to have an instant visualization of the MS camera with a few vegetation indices like NDVI or NDRE while flying over your trials - Or wether to have an instant RGB camera feedback

3/ The RTK Precision & The Great Battery Life Are Very Convincing

RTK means Real Time Kinematic, and this geolocation technology allows a centimeter-level positioning of the device, with real-time synchronization, will flying above your trials. Like the latest generation of portable drones from the DJI family, the new Mavic 3M comes as standard with an RTK-precision GPS module mounted on top of the drone that will ensure great image georeferencing and easy alignments while reconstructing your Orthomosaic.

The battery life is also great, DJI mentions 43 mins of flight duration in perfect conditions. We actually measured it flying for 32 mins above a wheat field at 12M high while capturing both RGB and MS images, with a single battery. It is also more silent and compact than previously. in addition it fits easily in a backpack with the 2 batteries that comes as standard with the drone.

To compare it to the previous Phantom 4M, the battery-life is improved due to the lightness of the device and the improved efficiency of the fast-charging lithium batteries. We need to make further testings on this but it seems like we can have a significant 35% to 50% of additionnal battery-life than the Phantom 4M.

4/ A Price That Makes It A Highly Competitive Tool

With all those features packed into one device, the great surprise is also the price, selling at around 4,300€, the Mavic 3M is giving access to the best drone technology for less money than before if we compare it to another member of the DJI family, the Matrice 300 equipped with two gimbals + two sensors, which we recommended a lot in the past and that costs around +20,000€ for almost the same technology. With the Matrice 300, the RGB camera would be better, however you’ll access the same range of traits with the Matrice than with the Mavic 3M.

Overall, the new Mavic 3M is more precise, more easy to operate, more reliable in terms of image acquisition, faster and less expensive than ever. The combined sensor head will facilitate you accessing most valubale traits for drone phenotyping such as vegetation indices and radiative transfer traits alongside counting and quality traits within one single flight, with less energy and less money spent. It's probably the biggest revolution in drone phenotyping since the establishment of the Mavic range. We strongly recommand this new Mavic 3M for most of your phenotyping applications.

We will soon make further testing of this Mavic 3M in various conditions and update this post with our latest conclusions. In the meantime, feel free to grab a time to discuss drone image analytics for phenotyping with one of our experts using the calendar below!

Sincerely,
Your Hiphen Team.