A Birds Eye View On Crops
Monitoring crop biomassAs farming is all about the production of (edible) biomass, monitoring the development of the crops is important for farmers to take management decisions. Drone images are very well suited for this type of application. One of the simplest approaches is to use drones to monitor the ground coverage of (individual) crops throughout the growing season. We can train computer algorithms to recognize the difference in appearance between crop pixels and non-crop pixels (e.g. shade, bare soil and weeds), so they can learn to automatically extract all the crop pixels from drone images. Based on the classification (crop or non-crop) of the pixels, maps can be derived where areas with lower crop coverage can be detected and decisions can be made for remediation (e.g. fertilizer or herbicide application).
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Revolutionising the Food Chain with Technology
Counting Flowers and FruitsWith drone images, we can estimate the number of fruits in apple or pear orchards well before their actual harvest dates. This allows the fruit farmers to efficiently organize the harvest and storage of their fruits. In spring, we can already get a first idea about the potential harvest by counting the number of flower clusters. As it would take a long time to do this counting manually, the farmers prefer a more automated approach. In the left pane of figure 5 below, you can see that on a drone image, the white flowers of pear trees are quite distinct from their surroundings. This means that they can easily be distinguished with the use of simple computer classification algorithms. In the middle pane, these flower pixels have been highlighted in blue. As multiple pixels correspond to the same flower, pixels close to each other are grouped, as shown as in the right pane. Figure 5: Counting flowers and fruits (Click to expand)
Crop vitality assessmentFor farmers, it is really important to closely monitor the health and vitality of their crops, as this allows them to quickly respond to stressors like droughts, plagues and diseases. Drone cameras can capture the world in those colors that we can see with our human eyes (visible wavelengths), but they can also capture ‘colors’ that are invisible to us, like infrared light. When plants encounter stress, the chemical composition of their leaves as well as their internal structure are altered. Changes in a plant’s chemical composition, especially leaf pigments like chlorophyll and carotenoids, mainly have an impact on the visible wavelengths, whereas changes in the tissue structure mainly influence the invisible infrared wavelengths. Therefore, the ratio of infrared to visible light can give us a good indication of the plant’s vitality or health. Several plant health indicators, called ‘vegetation indices’, have been developed and used for the early detection of stress in crops. The figure below displays two of these vegetation indices related to leaf pigments for an orchard. Based on the vegetation index values the stressed plants in the top part of the parcel can clearly be distinguished from the healthy plants in the bottom part. Figure 6: Crop vitality assessment (Click to expand)
ConclusionAs illustrated with the different concrete examples above, drones can be a very useful source of information for farmers. Drones can help them portray the within-field variability in crop productivity and vitality; even up to the level of the individual plant. As such, they can inform farmers on where, when and how to (re)act in order to optimize their harvest. Moreover, they can provide production estimates early in the growing season, allowing farmers to plan ahead in terms of management, harvest and storage capacity. For the interested readers we happily refer to some key literature that expands on current drone applications in agriculture. Please the the References document in the Downloads section below.
Revolutionising the Food Chain with Technology
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