There are two types of remote sensing
- Active remote sensing
- passive remote sensing
- Active remote sensing
to be active remote sensing they must offer their own source of energy in order to illuminate the items they are studying.
An remote active sensor emits radiation in the direction of the studied target. The sensor then detects and measures reflected or backscattered radiation from the target.
And also active remote sensing has been employed for a number of security purposes, including monitoring in the ocean and the Arctic. The double-bounce dispersion, has supplied important information in search and rescue missions.
what the advantages ?
provides two primary benefits
1. The ability to collect imagery at all hours of the day and night.
2. Clouds and bad weather don’t seem to bother it.
example of active remote sensing
a. Shuttle radar topography mission (SRTM)
b. Light detection and Ranging (LiDAR)
2. passive remote sensing
Passive remote sensing is the study of the interaction between a light source and various Earth surface characteristics, each of which has its own spectral response.
Radiation is supplied by two sources. The sun is the source of visible to shortwave infrared light gathered by remote sensing systems.
A portion of the radiation received by a sensor was reflected at the earth’s surface, while the remainder was scattered by the atmosphere and never reached the earth.
Thermal radiation released directly by materials on the earth interacts with self-emitted thermal radiation in the atmosphere as it propagates upward in the thermal infrared.
example of passive remote sensors
Film photography, infrared, charge-coupled devices, and radiometers are examples of passive remote sensors.
disadvantages
- difficult to record a data during night time
- some of a sensor may fail because of energy shortage
- atmospheric impact is high
