Remote Sensing Technologies: Raw Data Collection

The first type of ICT that improves productivity includes tools that collect agricultural data:

• Geographical information systems (GIS) collect geographic data through computer hardware and software to capture, store, update, and display all forms of geographically referenced information by matching coordinates and time to other variables. Data sets formed by GIS constitute “layers” of information (for example, on topography, population size, or agricultural household income) that can be merged and analyzed to establish relationships and produce maps or charts that visualize geographical traits (GIS.com n.d.).
• Global positioning system (GPS) is a satellite-based positioning and navigation system with three basic components: satellites that orbit the earth, control and monitoring stations on the earth, and the GPS receivers owned by users. GPS receivers pick up signals from the satellites, including precise orbital information (latitude, longitude, and ellipsoidal GPS altitude) of a given object or location, as well as the time. GPSs can function in any weather and are free for public use (GPS.gov n.d.; GARMIN n.d.).
• Satellite imagery is an image of Earth taken from satellites in orbit. There are four types of satellite imagery: spatial (size of surface area); spectral (wavelength interval); temporal (amount of time); and radiometric (levels of brightness)—which capture a variety of variables about a given area of varying size. The resolution (in meters) of these images depends on the satellite system used and its distance from Earth; weather can interfere mainly with satellite systems utilizing visible wavelengths of light. The cost of the technology depends on the satellite system used, on whether new or archive imagery is purchased, and on possible georeferencing to a coordinate system.
• Aerial photography and orthophoto mosaic. An aerial photo is an image (once a photograph, now a digital image) of the ground taken from an airplane, helicopter, or radio-controlled aircraft at a given altitude. Aerial images are presented as an orthophoto mosaic that is an alternative to a map. These images are higher in resolution (deci-meter) than satellite images, proving useful for those who want more details of the terrain such as crop conditions or land use. In addition, modern digital aerial photography is georeferenced—that is, each point has geographical coordinates, whereas satellite imagery requires georeferencing to be geographically accurate and compatible with other geographical data (for example, in GIS) (T. Jantunen, personal communication).
• Laser scanning, or light detection and ranging (LiDAR), is an active airborne sensor using a set of laser beams to measure distance from an aircraft to features on the ground. Airplanes and helicopters can be used for laser scanning. The data from laser scanning are three-dimensional at very high accuracy, and they also allow ground elevation under the tree canopy to be measured. The elevation accuracy of laser scanning data is much better than aerial photography, which makes laser scanning useful for accurate topographic mapping where elevation is critical. The data can also be used to measure forest attributes such as the height and density of trees and thus the volume (aboveground biomass) of the forest(T. Jantunen, personal communication).