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Basics of GIS

GIS stand for Geographic Information System. It is an Information system designed to work with data references by Geographical or Spatial Coordinates. The below discussion about the basics of GIS and Remote Sensing.

GIS & RS Basic

Aerial Photography

Photography from Airborne platforms.


Ratio of the amount of Electromagnetic energy reflected by a surface to the amount of energy incident upon it.


Elevation above or below a reference datum, its z-value in a spatial address.


AM- Automated Mapping, FM- Facilities Management. AM/FM applications are similar to the GIS system. It is most commonly describes databases designed to manage networks of roads, pipes, and wires, Area.

Areal Interpolation

The process by which data from one set of source polygons are redistricted onto a set of overlapping but non hierarchical target polygons.

Attribute Data

Qualitative or thematic data that relate to a specific, precisely defined location. The data are aften statistical, text, images, or multimedia.


Advanced wide field sensor. An IRS sensor first carried by Resourcesat-I.


A wavelength interval in the electromagnetic spectrum.


An ideal substance that absorbs the entire radiant energy incident on it and emits energy at the maximum possible rate per unit area at each wavelength for any given temperature.


The art and science producing maps, charts, and other representations of spatial relationships.


A point of the geometric center of a polygon, this can be used to represent to polygon as a point.


An imaginary line drawn on a map joining all the points on the earth that are at the same height above the sea level.


Linear or angular quantities which designate the position of a point in a reference or grid system.


A collection of information related by a common factor purpose.


Database Management System. Software designed to access and store attribute data.


The components of a Remote sensing system, that converts electromagnetic radiation into a signal that is recorded.


The vertical distance from a datum usually mean sea level, to a point of object on the earth’s surface. The z-value in a spatial address.


The process of altering the appearance of an image, so that the interpreter can extract more information. Enhancement by digital or photographic method.


Earth Observation Satellite Company. A private company contracted to the US Government to market Landsat data.


European Remote-Sensing Satellite. A series of remote sensing satellites launched by European Space Agency.


False-color composite. A color image where parts of the non-visible electromagnetic spectrum are expressed as one or more of the red, green, and blue components. The most commonly seen false-color images display the near infrared as red, red as green, and green as blue.


The process of assigning latitude and longitude to a point based on street addresses, city, state, and zip code.


A Geodatabase is a database designed to store, query, and manipulate geographic information and spatial data.


A processing of assigning geographic coordinates system to a layer of data.


It is refers to satellite traveling at the angular velocity at which the earth rotates.


Geostationary Operational Environmental Satellite. A NOAA satellite series.


A network of lines on a map or chart representing the parallels of latitude and meridians of longitude on the earth.


Multipurpose Indian satellite series, launched by GSLV.

High-pass filter

A spatial filter which selectively enhances contrast variations with high spatial frequency in an image. This method use for edge enhancement and improves the sharpness of the image.


Haute resolution dens le visible. It is designed for SPOT.


Conveyed or moved through the air. Balloons and aircraft are broadly grouped as airborne Remote Sensing platform.

Along-track Scanner

The along-track scanner, use a line of detectors arranged perpendicular to the flight direction of the spacecraft. An along-track scanner also known as an push broom scanner.


Information transmitted by each satellite, on the orbits and state of every satellite in a GNSS constellation. Almanac data allows the GNSS receiver to rapidly acquire satellites shortly after it is turned on.


Area of Interest.


A market analysis GIS Software package since the GIS computing was workstation-based produce by Esri.


Augmented Satellite Launch Vehicle. It is a Indian launch vehicle.

Atmospheric Window

Wavelength intervals of electromagnetic spectrum at which the atmosphere transmits most electromagnetic radiation.


Geographic orientation of a line given as an angel measurement of degrees, clockwise from the north.


The number of cycles per second between the limits of a frequency band, used for data transmission. It is a range electromagnetic spectrum.


A buffer is a polygon that encloses all areas within a set distance of the spatial features (points, lines, and polygon)


A series of Indian Remote Sensing Satellite for cartographic application.

Change Detection

Sensing of environmental changes between two or more time periods.

Control Point

Any station in a horizontal or vertical control system that is identified on a photograph or digital image, and used for the correlating the data shown on that photograph or image.


A mathematical surface on which a mapping and coordinate system based, Value- WGS84 = World Geodetic System 1984.


Digital Terrain Model. A land surface represented in digital form by an elevation grid or lists of three-dimensional coordinates along with related information, such as slope, aspect, hillshade, etc.


The process by which a body emits EMR (Electromagnetic Radiation) usually as a consequence of it’s temperature only.


Earth Observing System. A series of small to intermediate sized spacecraft that is the centerpiece of NASA’s mission to the earth planet.


Earth Radiation Budget Sensor System. The carried by NOAA Satellites.


Enhanced Thematic Mapper. A sensor carried on Landsat 7.

Fiducial marks

Reference points that are seen in the resulting photograph that come from a point fixed to the camera body.

Focal Length

In cameras the distance from the optical center of the lens to the plane at which the image of a very distant object is brought into focus.


The study of the size and shape of earth’s surface, measurement of the position, motion of points on the surface, and configuration of area.


A GIS operation used to manipulate Geographic data. A typical geoprocessing operation takes an input dataset, performs an operation on that dataset, and returns the result of the operation as an output dataset.


Global Earth Observation Satellite Systems.


Global Navigation Satellite System. The Russian GNSS System.

Ground control

Ground control obtained by ground surveys as distinguished from control obtained by photographic methods, horizontal, vertical, or both.


Geosynchronous satellite launch vehicle, Indian launch vehicle.


High resolution infrared spectrometer. It is carried by the NOAA satellite.


A graphic display used to plot of frequency with different values of a given variable occur.

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