Precision agriculture nowadays uses data from satellite images, sensors in the ground, weather stations, etc. but also multispectral, hyperspectral and thermal sensors.
The thermographic survey by drone makes possible to support the research thanks to the experimental analysis carried out by the engineers of institutes and laboratories performing in agronomic research. It also serves farmers to inspect, control and improve crop management to optimize harvests.
Drones prove indeed to be the perfect partners for this type of missions. Rapidly deployed, UAVs cover plots of large areas in a short time by recording high-precision data in order to obtain Normalized Difference Vegetation Index (NDVI) mapping.
The photogrammetric processing of the images facilitates the localization of the affected areas, thus making possible to precisely target the application of appropriate treatments, limit the use of fertilizers and better manage the crops irrigation.
UAV survey in real conditions
Our teams received recently the mission to carry out several surveys in the countryside.
The goal was to record radiometric videos by flying UAV over experimental cultures.
The recorded thermograms had then to be analyzed with Optris’ PIX connect software, and then used to reconstruct orthophotos afterwards, thanks to Agisoft Photoscan Pro – one of the state of the art software that performs photogrammetric processing of digital images.
At the end of this chain are provided data that are extremely valuable for the scientists, allowing them to precisely visualize the entire state of health of the plots.
These images had to be georeferenced accurately by means of ground control points (GCPs).
It would also have been possible – in other circumstances – to georeference directly the videos, either by injecting into the Optris thermal camera the GPS data from the drone, or by using a separate GNSS receiver connected to the thermography system.
In our case, the alternative solution to the ground control points (GCPs), in order to obtain the required accuracy, could have been to use a drone equipped with a precision GNSS system, such as the Septentrio’s AsteRx-m2 UAS RTK board. This method is indeed the fastest and the most efficient when parts of the field are not easily accessible to place the targets (GCPs), or when the area to cover is too wide.
Drone equipement deployed on the field
For this operation, AltiGator’s team used an OnyxStar XENA drone together with its embedded Optris PI 450 thermal camera and its mini PI Lightweight computer. The camera was installed on an OnyxStar brushless gimbal.
An HD video transmission link was allowing the pilot to follow in real time the progress of the mission. The camera was triggered directly from the ground control station. Between two flights, the collected data were downloaded from the Optris PI Lightweight mini-PC via a USB key and verified in order to validate their integrity.
Result of the thermographic survey mission
Thanks to this mission, it has been possible to map the different cultivated zones of the parcels overflown by the drone and the thermal camera.
The results are excellent. They confirm that drones have a major role to play in agronomic research.
AltiGator systems have also proven to perfectly comply with such precision applications.
Thanks to its technical characteristics and performance, the XENA Thermo drone is indeed the ideal tool for the rapid capture of qualitative radiometric data.
Processing and rigorous analysis of the geolocated thermograms obtained makes possible to efficiently guide the scientists in their decision-making process.
The XENA Thermo is a professional, robust and versatile UAV system that can easily embed the Optris PI 450 or 640 with its PI LightWeight computer, two thermal imaging cameras designed for aerial capture.
These allow the recording of precision radiometric data and are perfectly adapted to aerial use by drone thanks to their compactness and light weight.
Conclusion
This UAV mission confirms once again that agricultural drone technology is an extremely efficient way of gathering crop growth and health status information. Thanks to the combination of aerial thermal survey together with photogrammetry, the benefits of drones in agriculture are becoming more evident in agronomy.
Drone applications in agriculture were frequently known for crop spraying in the past, which is interesting for relatively small plots and reduced areas.
With this mission’s UAV gathered data, agronomists have valuable information to study more in depth cropdusting and health research.
