In the last few decades, numerous commercial and custom-built imaging sensors have been developed and deployed on different platforms for diverse remote sensing applications, including precision agriculture. Remote sensors are traditionally carried on manned aircraft and earth-orbiting satellites, but some sensors can be handheld or mounted on ground-based vehicles. Recently, unmanned aircraft systems (UAS) have become a popular remote sensing platform due to their low cost, high spatial image resolution and ease of operation. Manned aircraft-based sensors are commonly referred to as airborne sensors, while satellite- or spacecraft-based sensors are also known as satellite or spaceborne sensors. Both non-imaging and imaging sensors can be carried on all platforms, though non-imaging sensors, including multispectral radiometers and hyperspectral spectroradiometers, are primarily used for ground-based applications.