An Overview of Remote Sensing

Remote Sensing
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Remote sensing is the examination of an area from a significant distance. It is used to gather information and imaging remotely. This practice can be done using devices such as cameras placed on the ground, ships, aircraft, satellites, or even spacecraft.

Today, data obtained through remote sensing is usually stored and manipulated with computers. The most common software programs used for this include ERDAS Imagine, ESRI, MapInfo, and ERMapper.

A Brief History of Remote Sensing

The science of remote sensing began in 1858 when Gaspard-Felix Tournachon first took aerial photographs of Paris from a hot air balloon. One of the first planned uses of remote sensing in its most basic form was during the ​Civil War when messenger pigeons, kites, and unmanned balloons were flown over enemy territory with cameras attached to them.

The first government-organized air photography missions were developed for military surveillance during World Wars I and II. However, it was during the Cold War that remote sensing was most widely used. This field of study has developed since its beginning to become the highly-sophisticated method of indirect information acquisition that it is today.

Satellites were developed during the late 20th century and are still used to gain information on a global scale, even about planets in the solar system. The Magellan probe, for example, is a satellite that has been using remote sensing technologies to create topographic maps of Venus since May 4th of 1989.

Today, small remote sensors such as cameras and satellites are used by law enforcement and the military in both manned and unmanned platforms to gain information about an area. Other modern remote sensing methods include infra-red, conventional air photography, and Doppler radar imaging.

Types of Remote Sensing

Each type of remote sensing is differently suited for analysis—some are optimal for closer scanning and some are much more advantageous from great distances. Perhaps the most common type of remote sensing is radar imaging.

Radar

Radar imaging can be used for important safety-related remote sensing tasks. One of the most important uses is for air traffic control and weather detection. This can tell analysts whether adverse weather is on its way, how storms are progressing, and

Doppler radar is a common type of radar that can be used both to collect meteorological data and by law enforcement to monitor traffic and driving speeds. Other types of radars can create digital models of elevation.

Lasers

Another type of remote sensing involves lasers. Laser altimeters on satellites measure factors like wind speed and the direction of ocean currents. Altimeters are also useful for seafloor mapping as they are capable of measuring bulges of water caused by gravity and seafloor topography. Varied ocean heights can be measured and analyzed to create accurate seafloor maps.

One particular form of laser remote sensing is called LIDAR, Light Detection and Ranging. This method measures distances using light reflection and is most famously utilized for weapons ranging. LIDAR can also measure chemicals in the atmosphere and heights of objects on the ground.

Other

Other types of remote sensing include stereographic pairs created from multiple air photos (often used to view features in 3-D and/or make topographic maps), radiometers and photometers that collect emitted radiation from infra-red photos, and air photo data obtained by satellites such as those found in the Landsat program.

Applications of Remote Sensing

Uses for remote sensing are diverse but this field of study is mainly conducted for image processing and interpretation. Image processing allows photos to be manipulated so that maps can be created and important information saved about an area. By interpreting images obtained through remote sensing, an area can be closely studied without anyone needing to be physically present, making the research of dangerous or unreachable areas possible.

Remote sensing can be applied to various fields of study. The following are just a few applications of this continually-developing science.

  • Geology: Remote sensing can help map large, remote areas. This makes it possible for geologists to classify an area's rock types, study its geomorphology, and track changes caused by natural events such as floods and landslides.
  • Agriculture: Remote sensing is also helpful when studying vegetation. Photographs taken remotely allow biogeographers, ecologists, agriculturalists, and foresters to easily detect what vegetation is present in an area as well as its growth potential and conditions optimal for survival.
  • Land-use planning: Those studying land development can apply remote sensing to studying and regulating land usages over wide expanses. The data obtained can be used for city planning and the modification of the environment more generally.
  • Geographic information system mapping (GIS): Remote sensing images are used as the input data for raster-based digital elevation models or DEMs. Air photos utilized through GIS can be digitized into polygons that are later put into shapefiles for mapmaking.

Because of its varied applications and ability to allow users to collect, interpret, and manipulate data from inaccessible locations, remote sensing has become a useful tool for all researchers regardless of concentration.