Editor’s note: The following was written by Ryan Bergman, Iowa State University program coordinator in ag technology, for the Integrated Crop Management News blog.
The use of aerial imagery in production agriculture has continued to grow and evolve over the last several years since its debut on the market. With significant changes in how imagery is captured and processed and the quality of images available, there are now many applications for this technology on farms.
With many choices available for capturing aerial imagery, it’s important to understand the differences and applications to help you make the best decisions for your operation.
The three main options commonly used for aerial imagery in the ag industry are UAVs (unmanned aerial vehicles, or drones), manned aircraft (typically small planes) and satellite-delivered imagery. Drones typically deliver the best image resolution, as they are equipped with high quality cameras and can fly at lower altitudes than manned aircraft. As you can see in Figure 1, imagery taken with a UAV can provide the ability to observe individual rows and plants, as well as clearly identifying planter skips and other areas of lower yield.
Drones also offer the best flexibility for timing the capture of images, ensuring that weather and lighting are good for collecting imagery.
While battery life for drones has made substantial improvements in recent years, this is still an important limiting factor to consider.
Manned aircraft can also provide high-quality, valuable imagery without the time commitment or overhead costs of using a UAV. Targeting specific weather or times of day is not as easy with manned aircraft because of the preparation required. However, many companies now offer packages that include multiple flights and field maps throughout the growing season for a fixed price.
This can be valuable for those interested in aerial imagery without the time commitment and costs of owning a UAV.
Satellite imagery has been around for decades but continues to make improvements to the quality and timing of imagery available. Many services offer image resolution as high as one meter per pixel, but satellite imagery is often hindered by weather and cloud cover. Several days of overcast could result in missing a desirable image of your crop at a specific growth stage.
An advantage of satellite imagery is it’s archived, enabling you to purchase images from last week or even from years ago. Some examples of commonly used ag satellite imagery providers are Planet and Satshot.
UAVs continue to be a popular option. Fixed wing drones are more expensive and more difficult to operate, which quickly resulted in development of app-based software to use quadcopter drones for collecting georeferenced images of fields and stitching them together. Commonly used apps include DroneDeploy, Pix4D and Sentera.
While fixed wing drones still have some advantages when mapping larger field areas, the quad copter type still tends to be most common in the ag sector due to their price point, ease of operation, and ability to integrate with third-party apps.
This change allowed easier access to high-quality field maps, and since then imagery has become widely adopted in the ag industry by everyone from seed companies and ag retailers to farmers using drones to scout their fields.
While many product types and services focus on providing orthomoasic images (georeferenced field maps from many images being stitched together), quadcopter-style UAVs also provide other unique and valuable information. The ability to receive a live video feed from the UAV and gain a high level view of the field to evaluate crop vigor, damage, equipment job quality, etc. allows you to evaluate your field in real time. This can often provide instantaneous knowledge about your field and allow for quick management decisions to avoid or correct issues identified.
Pros: Simple to use, instantaneous feedback for scouting, can provide high-resolution maps
Cons: Often only able to capture a single image type (RGB, NIR, thermal) during flight, productivity often limited by battery life, field maps can be large and difficult to manage
Fixed Wing UAV
Pros: Automated flights, can cover more acres/hour when mapping compared to a quadcopter
Cons: High cost to purchase, more complex to operate, field maps can be large and difficult to manage
Pros: Lower overhead cost than owning a UAV, typically provides multiple stitched images (NIR, RGB, NDVI, etc.)
Cons: Longer wait time between ordering and receiving images/maps, less flexibility with flight altitude (i.e. image resolution) and sensor packages
Pros: Low cost, archived historical data, smaller, more manageable file sizes
Cons: Lowest resolution of all options, images often may be impacted by cloud cover