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Showing posts from October, 2012

What is Shape File ?

Cover Feature: Shapefile is constructed to link a point in a digital map to a database storing related retrievable informations about the point. A vector data (points, lines, or polygons) storage format for storing the location, shape, and attributes of geographic features(ESRI Def). Shapefiles can be of three types : 1. Point Shape : A shapefile consisting of points which is used to represent datasets about a location(city,town etc.) 2. Polyline Shape : A shapefile of more than one point shape is known as Polyline shapefile and is used to represent information regarding line features like river,road,pipeline etc. 3. Polygon Shape : The polygon shapes are developed with the help of more than two points representing the vertices of a polygon.This type of shapes are used to exemplify a region like watershed,pond etc. Any shapefile can be zoomed in or out without any deformation in the spatial representation and thus such files are grouped under Vector images. Summary

Definition of GIS,Remote Sensing and Image processing

Category Other Output Type Information/Fact TAG GIS Type of Message * Message Cover Feature GIS is defined as Geographic Information System .It is a tool to represent and/or retrieve data spatially.The spatially linked data are generally stored in a Geo-referenced database. Remote Sensing is a procedure to capture image of a remote object by various type of optical/thermal/sound wave active/passive sensors.Active sensors send an artificial signal (microwave or sound pulse) and capture the image by sensing the reflectance of the same where as passive sensors only detects or absorb light or any other naturally available energy signal reflected from the target object. Whereas Image Processing can be defined as the retrieval of information from an image by converting the same into DN values shown within the pixels(units which constitutes a raster image) of the image.