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1. Geographic Information System: Geographic Information Systems are computer
based decision support tools to capture, manipulate, process and display
spatial or geo-referenced data. They contain both geometry and attribute
data and are distinct in their capabilities to perform spatial operations
of integration.
2. Cartography: It is
the art of map preparation using actual (Real World) coordinates of the
earth
3. Raster Map: It can
be considered as the image input to the GIS system which is not having any
information associated with it. The raster map could be a scanned image or
remotely sensed image
4. Vector Map: It can
be considered as the intelligent map which could provide you any real world
information whatever you want.
5. Layers: Layers
are superimposed on the raster map to show the real world entities e.g.
Point, Line, Polygon, Text features etc. In-fact it represents the real
world entities present on the earth and the associated information with
those entities.
6. Virtual Layers: In OOP’s
concept virtual layer means it does not exist in isolation but associated
with a subclass of a class and make the group of objects of a subclass of a
class distinguishable by giving them different display features e.g. color,
pattern, or a complete different look. Note: Even if the virtual layers
change the appearance of the objects of a subclass of a class the original
representation of the objects still exits.
7. Interpolation: Interpolation
is a method of approximation of point height from known random points to
unknown grided points. The grided plot is generated by defining the maximum
tolerance distance between any two points. The distance between any two
points could be defined in degrees; kilometers; meters etc. when you are
handling large maps then specify the tolerance distance in kilometers or
degrees.
8. Contour: It is
represented in the line feature with a constraint that no two lines must
intersect with each other in any circumstance. This feature is used to
represent many spatial information of the earth’s surface e.g. Height
information, temperature information, whether forecasting information,
information related to oceanography, hydrology etc and many more.
9. Mapping: In GIS
arena this term is commonly applied for measurement of spatial (earth’s
space) information in many contexts e.g. mapping of boundaries, analysis on
the map using real life attribute associated to any real world entity etc.
10. Isochrones: These are
the polygons whose vertices show the reach ability from any point under
consideration to any node of the polygon under a certain distance or time
limit.
11. Catchments Area: The vertices of the Isochrones show the
catchments area. The term reach ability along the isochrones vertices and
catchments area could be used interchangeably.
12. Buffer zone: Buffer zone is a
topological tool which represents a uniform wide band surrounding an object
representing an area of influence, whose geometry is defined by set
distance from one or several selected objects. This distance is defined by
the user as a constant, or field value, value.
13. Topology: The study of geometrical
properties and spatial relations which remain unaffected by smooth changes
in shape or size of figures.
14. DTM: This means “Digital
Terrain Modal” of the mapped surface. It represents the 3D view of any
terrestrial surface showing various features of that terrestrial surface in
3-Dimension. This is particularly useful in military applications e.g.
plotting the path of convoy movement in high altitude zone or moorlands
(Cross country movement).
15. DEM: This means “Digital
Elevation Modal” of the mapped surface of the earth. It represents the
elevation of earth surface in 3-Dimensional view, but before plotting DEM
there must exist a 2-Dimensional contour plot on the map with exact height
mapping.
16. Altitude: This
represents the height of the points plotted on the earth surface.
17. X,Y,Z: This
triplet represents the real world coordinates of the projected 3-D earth
surface on to the plane. Here X, Y represents the locational information
and Z represents the height of the earth surface.
18. Snap: In GIS
arena this means capturing the information of any point under
consideration.
19. Length: In GIS arena this
represents the distance between the first and last point of a line. The
coordinates of the first point of a line is stored in X and Y and the
coordinates of the last point of a line is stored in X’ and Y’.
20. Area: This
information is only associated with polygon object on the mapped surface
showing the area of an entity like, Continent, Country, State, County,
Districts etc.
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