If you currently fly drones on your experimental fields to measure plants count or other plant characteristics such as plant height or flowering, or if you’re just exploring the drone-based aerial phenotyping world and you’re unsure which type of drone to choose from, then this guide is right for you.
GSD is the Key
Before we dive into the specifics of drone flight configurations, it is important to define GSD. GSD is the real-world size of a pixel in your images. It means Ground Sample Distance. In an orthophoto or any other georeferenced image, it is the distance between two consecutive pixel centers measured on the ground. The lower the GSD, the smaller the image pixel, the more detailed the map.
The type of analytics you need at a given crop stage will determine the GSD. It is crucial to find the best compromise to optimize quality results and work efficiency: flying too high will increase the GSD and reduce the image resolution, which can prevent you from getting an accurate plant count, for example. Flying low will lead to high detailed information, which is great to generate a detailed inventory of a crop, but you should consider the risk on data quality (blurry image and higher risk of weather and crop changes due to increased flight time) as well as a longer flight and data processing time because there will be more images to process.
Your desired trait defines your GSD, thus your drone altitude
Delair.ai cloud platform helps you extract various analytics than can be used to measure traits along the crop season. A good rule of thumb is to use a target GSD between 6 and 10 cm if you’re planning to do any of the following:
Measure plant health
Vectorize your micro-plots to define/geolocate their boundaries
Measure plant height
Characterize flowering
Extract stay green
Map the fraction of ground covered by green vegetation (FCover)
This range, which corresponds to a flight altitude between 90 and 150m with the UX11AG drone, is sufficient to get you accurate analytics.
The only traits that generally require a much lower GSD are the plant gap & count as well as emergence quality, especially if your plant canopy size is rather small (<12cm) since you have to extract them at an early stage of development.
For the complete article on agricultural drone best practices click here.
