Types of remote sensing

Sensor description

Example of imaging sensors

Resolution         Limitations

Application in agriculture

Other applications

1.    Optical Imaging (continued)

It acquires images in about a 100 or more

ENVISAT MERIS

Spatial: 300, 1200 m

• Inventory and yield estimation.

• Evaluation of tropohospheric aerosol

d.  Hyperspectral
2. Microwave Imaging

contiguous spectral bands. The precise spectral information enables better characterization and identification of targets.
Encompasses both active and passive remote sensing. It covers long wavelengths from 1cm-1m, which can penetrate through cloud cover, haze, dust, and all but the heaviest rainfall all day and all weather imaging.

Hyperion

Spectral: 15 bands Temporal: 3 days
Spatial: 30 m Spectral: 220 bands Temporal: 16 days

• Crop type mapping • Monitoring of seasonal land cover changes. • Global vegetation monitoring
• Precision farming, crop type mapping, monitoring of crop health, moisture and maturity.

properties, hazard monitoring
• Measures sea surface temperature, color and surface roughness • Coastal management (monitoring of phyto-planktons, pollution and bathymetry changes)

(widely used bands) a. C Band

8,000-4,000 MHz; (3.8-7.5 cm)

RADARSAT-SAR
(5.6 cm)

Spatial:                • Image 8,25,30,50,          distortions. 100m                   Extensive Spectral: C          shadowing band                    of areas Temporal: 24       characterized days                    with relief. • Coarse

• Crop monitoring and forecasting, crop mapping

• Flood detection, for disaster management, risk assessment, pollution control (oil spill), coastline mapping.

b. L Band
3. Light Detection and Ranging (LIDAR)

2,000-1,000 MHz; (15.0-30.0 cm)
An active sensor that transmits laser pulses to the targets and records the time the pulse returned to the sensor receiver. Laser is able to provide light beam with high intensity, high collimation, high coherence, high spectral purity, and high polarization purity.

ALOS-PALSAR
(1270 MHZ)
LIDAR (airborne)

Spatial: 10-100   resolution, m Spectral: L      especially band Temporal:   for passive 46 days               applications. • Radar images are rather difficult to deal with. The few commercial software packages that exist to deal with radar imagery offer a limited amount of functions. • Results are better when combined with optical images as they have been proven complimentary
Spatial: 0.75 m    • Disadvantages Spectral: 1.045- are low 1.065 urn             coverage area Temporal:            and high cost dependent on      per unit area flight schedule    of ground coverage. It is not cost-effective to map a large area using an airborne remote sensing system.

• Agricultural monitoring
• Crop monitoring, plant species detection, can be used for agricultural planning and crop estimation

• Distinction of forest from grassland, land cover classification volcanic activity monitoring, flood monitoring, landslide and earthquake detection, detection of oil slick, forest biomass estimation.
• Forestry management, shoreline and beach volume changes lines, flood risk analysis, habitat mapping, subsidence issues, emergency response, urban development, and monitoring of environmental changes.

Source: Authors' elaboration.