The science of remote sensing allows one to learn about an area's physical characteristics without physically being there. It enables users to record, see, and examine features and objects on the surface of the Earth. Without making direct physical contact with the thing being investigated, remote sensing is the process of gathering data, detecting, analyzing, and monitoring the physical properties of an area by collecting radiation energy that is reflected and emitted from that area. The radiation or energy that is reflected is captured to do this.
By gathering imagery, we may categorize it into assessments of the land cover and other things.
Sensors, used in remote sensing to take data, can be stationed on the ground (in situ), in addition to being carried by satellites or aircraft. Active and passive sensors come in two varieties. Passive sensors pick up energy that is emitted or reflected from the environment; Active sensors emit their own energy to illuminate the items they are examining.
fig: remote sensing technologies with typical altitudes. ( image source : EarthHow.com)
Active Sensors : In order to scan the object, active sensors expend their own energy. Active remote sensing techniques like RADAR and LiDAR measure the lag time between emission and return.
Passive Sensors : These sensors collect radiation that the object or its surroundings emit or reflect. The most frequent source of radiation detected by passive sensors is sunlight reflection. Radiometers, infrared cameras, and photography are a few examples of passive remote sensors. Because passive sensors produce high-quality satellite pictures, they are increasingly widely deployed.
For the purpose of topographic mapping in the 1840s, tethered balloons were used to take the earliest examples of current remote sensing, which included crude images of the earth's surface. For military surveillance and reconnaissance during the First World War and the Cold War, systematic aerial photography was created utilizing adapted airplanes.
As the space program took off in the 1960s, instruments on Earth observing and weather satellites like the Nimbus and Landsat offered global measurements of different data for military, civil, and research uses. Lockheed Martin commissioned IKONOS, the first commercial satellite designed to gather images at extremely high resolution, which was launched in 1999 and decommissioned in 2015.
Remote Sensing Data Application.
fig : various uses of remote sensing ( image source : GIS Geography )
The uses for remote sensing are highly varied. They fall into two categories. Operational applications and applications in research of the Earth system's processes are two examples of the former. The former can be separated into the cryosphere, the atmosphere, the ocean, the land, and their interactions. Temperature, water vapor, aerosols, clouds, atmospheric components, greenhouse gases, sea surface temperature, salinity, wind, ocean color, sea surface height, topography, land cover, soil moisture, carbon cycle, sea ice, snow, and glaciers are all discussed in this chapter. The latter offers a wide range. There are too many operational application areas to address in this chapter. Numerical Weather Prediction (NWP) and weather forecasts, fisheries, and disasters including biomass fires, floods, ship navigations, and agriculture are among them.
Some important domains whereby remote sensing can be implemented :
Here, Finding each application individually -
1. Forecasting future landslides,
2. The study of climate change,
3. Identifying construction and structural changes,
4. Uranium enrichment center 3D mapping,
5. Aerial imaging for use in military surveillance,
6. Constructing a reference base map,
7. Throughout view of the property,
8. Creating automatic road networks,
9. Identifying land use and land cover, &
10. Uncovering historic archaeological sites, plus many more.
https://www.earthdata.nasa.gov/sensors ( about sensors )
https://tudip.com/blog-post/what-is-remote-sensing-and-its-applications/ ( application and introduction )
https://gisgeography.com/remote-sensing-earth-observation-guide/ ( main intro and title idea )