MAPOLOGY : GIS,Remote Sensing and Image Processing Tutorials

Baipatra: Introduction to GIS Coordinate Systems : The position of a point in a 2D or 3D surface is defined by a system of coordinates.There are mainly three types of Coordinate Systems that...

The first step in developing an interactive map linked to relevant data that you want to represent is to select the coordinate system with which you want to work.The tip is if you are working in a global scale use the global coordinate systems. If you are working within a country use the local coordinate systems.If the scale of you work is within the district/state then use cadastral maps. A single point can be represented by x and y axis of your paper,height and width of your room or even the global coordinate systems.Each of the representation will be correct but the resolution will be effected.In x and y axis of your paper the resolution will be best,in the height and width of your room resolution will be medium and in the global axis it will be poor. That is why there are various types of coordinate systems and they are utilized based on the spatial scale at which you are working.

Some free but useful software for working in GIS projects are : MapWindow GIS,Quantum GIS etc. The steps for creating a Geo-referenced and informative spatial database( or database linked to spatial points) is the following : a)Selection of Coordinate System b)Creating shape-files(line for digitizing road,rivers etc;polygon for digitizing water bodies,plantations etc. and points for indicating cities,places etc.)  c)Creating the attribute tables linked to the shape-files where columns represents different attributes and rows represents the sub-shapes representing different features of same shape(artificial ponds can be digitized with polygon shape-files and each pond can be digitized within single shape-file where each sub-shape will describe that kind of pond only)  d)After relevant informations are entered into the attribute tables data-sets can be represented with the help of different colours or degree of colours or different styles. Each of the a...

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 ...

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. ...