Altitude*; for orchards, we recommend flying higher than 150m/500ft (first check your local air regulations); however, if you are mapping field crops in an early stage, we recommend flying at 50m/165ft. Bear in mind that the minimum plant height for Agremo analyses 12 cm/5 in. Based on a 20 MP RGB sensor.
At the office
Making quality footage and turning it into actionable data is not always simple. Here’s what you need to do in order to master your first steps as a drone operator in agriculture.
1. Check the weather conditions that will occur in the particular area you are about to map and bear in mind that factors like cloudiness, wind speed, and precipitation play an important role as they may impact the quality of your images.
There are many online weather forecast services available. Some of them are:
TIP: Many of these online weather forecast services allow you to monitor cloud movements many days in advance.
2. Check the area which you are about to map. Pay special attention to:
– Road accessibility
– Internet connection
– No-fly zones
TIP: Download offline maps of the area to avoid internet connection problems.
3. Creating offline flight plans
Most platforms for autonomous drone flights offer the possibility to make offline flight plans. Some of them include:
DroneDeploy – https://blog.dronedeploy.com/flying-with-dronedeploy-just-got-even-better-7dc466958e94
Pix4D – https://support.pix4d.com/hc/en-us/articles/115002056523
Precisionmapper – https://support.precisionmapper.com/support/solutions/articles/6000185353-flying-offline
TIP: Offline flight plans can be of great use for areas with no internet connection.
4. Setting the flight parameters
Flight settings largely depend on the species you are about to map, as well as on the required image resolution. Here’s what we recommend:
Altitude*; for orchards, we recommend flying higher than 150m/500ft (first check your local air regulations); however, if you are mapping field crops in an early stage, we recommend flying at 50m/165ft. Bear in mind that the minimum plant height for Agremo analyses is 12 cm/5 in.
Overlap*; use 60% of sidelap and 70% of the front lap for orchards, and 75% of sidelap and 80% of the front lap for early-stage field crops.
Low-resolution example: Altitude 150m/500ft; Sidelap 60% Frontlap 70% = 5cm/pix; 2in/pix
High-resolution example: Altitude 50m/165ft; Sidelap 75% Frontlap 80% = 1.5cm/pix; 0.6in/pix
TIP: Lower altitude and higher overlapping will increase the number of images and the time required for the flight, but it usually pays off, as this helps obtain high-resolution images.
Altitude* (AGL – above ground level); refers to the height of the flight in relation to the place from where the drone is going to take off.
Overlapping* refers to the percentage of both side lap and front lap. The side lap is the percentage of overlap between each leg of a flight, while the front lap refers to the percentage of overlap between one image and the next.
Altitude and overlap are certainly important flight planning parameters, but several other factors should be taken into account as well:
Mapping time: the best time for agricultural mapping is between 10 am-2 pm because the sun throws fewer shadows during this period. Overcast weather is usually not a problem, but make sure that there are no major cloud gaps, which would lead to unfavorable shadows in your footage. It’s usually better to map when the entire area is cloudy instead of waiting for some of the clouds to disappear and have at least a few cloudless spots.
Maximum flying speed: the recommended flying speed depends on the required image resolution. For lower resolutions, increase your flying speed (to about 15m/s); for higher image resolution, set your flying speed to about 7-9 m/s.
Flight route: Adjusting the flight route will affect your flying time and the map quality alike – make sure the route you choose meets the required quality.
Polygon creation: before planning a mission, make sure to mark all the required polygons. Tip: the polygons should be a little larger than the field you are about to map. Here’s an example:
Also, since large fields cannot be mapped in one single flight, it’s necessary to create mapping zones. Make sure that the overlap in these zones is big enough.
TIP: Individual zones should not be larger than 500×500 meters or 1650 x 1650 ft. This is also one of the legal requirements that drone operators have to take into account and which states that the aircraft needs to remain beyond visual line of sight (or BVLOS).
https://support.dronedeploy.com/docs/flying-a-larger-area-with-multiple-batteries
https://support.dronedeploy.com/docs/best-practices-to-fly-and-stitch-crop-imagery
5. Mapping Equipment
After creating a polygon for the mission, you need to check your equipment and make sure you have everything at hand for your mapping day:
– Drone batteries
– Station battery
– Tablet and/or phone battery
– Notebook/laptop battery (if required)
– SD card (make sure you have a formatted SD card, and a proper card reader – this will allow you to have a first look at the footage while you’re still in the field)
– The latest version of all the applications you are going to use (DroneDeploy, Pix4D, Precision Mapper, DJI Go, Litchi, etc.)
– All required cables for the station, drone, charging hub, mobile device, etc.
– Suspenders
– Reflective safety vest
– Inverters
– Small tools (screwdriver, pliers, tape, etc.)
– Sun protection (hat, cap, parasol, etc.)
– Water
– Ground truth marker
TIP: Always be prepared for harsh conditions on the field and never go into the field without lots of water, a few energy bars, and proper sun protection!
In the field
Pre-flight:
– Find a good place for takeoff and landing
– Look out for power cables that could interfere with your flying route
– Set up the aircraft
– Ground truth*
– Conduct flight
After the flight
– After conducting the flight, check the images on the SD card
– Make sure to remove the marker from the field
– Make sure to leave nothing behind
TIP: Keep in mind that many factors can affect your drone’s battery life, including wind speed, temperature, flight altitude, etc. This is why having an extra battery at hand is very important.
*Ground truth data is gathered by placing a 1x1m marker onto the field (one is enough; if you are looking for different types of stress, we recommend using several markers).
6. Data processing
Turn the images captured with your drone into a map, which can then be further analyzed in terms of weed, pest, plant numbers, etc. Here’s what you have to do:
– Upload the images from the SD card
– Stitch the images together to turn them into a map
– Upload the zip file with the according to tiff files to the Agremo app
You can perform these steps separately, or use the Agremo app on the DroneDeploy app market where all these steps can be performed in one place. Find out more about it here:
Tutorial How to use Agremo Plant Count & Health app on DroneDeploy App Market
Supported drones
Agremo analyses don’t require any additional equipment and can be requested with images captured with common commercial drones, both fixed-wing or multirotor. Many users choose to capture fields with DJI drones, but you’re free to choose the drone type that best works for you as long as the image quality meets the requirements.
TIP: Pay special attention to the characteristics of the drone you choose to work with. Fixed-wing drones have a bigger range, but also require larger landing/take-off zones. Multirotor drones have smaller landing/takeoff zones, but their range is smaller compared to the range of fixed-wing drones.
Supported sensors
Agremo analyses work with every available RGB sensor, which is the kind of sensor that comes with every DJI drone. Apart from RGB sensors, Agremo analyses also support thermal, NIR, or multispectral sensors.
TIP: Common RGB sensors are more than sufficient for most agricultural operations and analyses like the ones offered by Agremo. Consider purchasing additional sensors only if your targeted needs require you to do so.
