What are the different types of agricultural remote sensing, what is sensed by them, and how does remote sensing work?
Visible spectrum imagery consists of photographs, taken either from an aircraft or from a satellite. As the name implies, these types of images are what the normal human eye sees. Its advantage is that it is familiar and provides a photographic image that can be studied, enlarged, etc. Certain land features can be detected from the air with such imagery. Its use in assessing crop stress is limited to showing damage that is already visible. While of use in directing attention to remote or hard-to-reach areas (such as treetops, forests), it is of very limited use in agriculture that produces fruits and vegetables, since visible stress indicates only already-present damage and cosmetic appearance is very important in those crops. Near-IR (near infrared) or CIR (color infrared) photography consists of use of film that is sensitive to visible and near infrared light, exposed in a camera flown in an aircraft. It is not heat-sensitive because it is not sensitive to the far infrared portion of
