Why Open-Source Geographic Information System(GIS)?

    Geographic Information System (GIS) is an organized collection of computer hardware, software, geographical data and personnel designed to efficiently capture, store, update, manipulate, analyze, and display all forms of geographically referenced information”(ESRI).

       A wide variety of GIS software are available now a days, which are grouped into two broad classes as commercial software and Free and Open-Source software. Free and Open Source Software (FOSS) is computer software that can be classified as both free software and open-source software. The term 'free'  in free software implies the 'freedom' of the user to  freely use, study, modify, and distribute the software. It actually refers to four kinds of freedom that it provides. 

  • The freedom to run the programs for any purpose.
  • The freedom to study how the programs work and adapt it to users needs.
  • The freedom to improve the program, and
  • The freedom to distribute copies of modified version to others.

    In the case of open source software, the source code is available to the user, so that anyone can inspect, modify, improve and distribute the software. To know more about open source, go to the link given bellow.

More about Open Source

     The benefits of using Free and Open Source Software  include decreasing software costs, increasing security and stability, protecting privacy, and giving users more control over their own hardware.

    When we think about open source Geographic Information System (GIS), a multitude of option comes to our mind. QGIS, GRASS, ILWIS, OpenMap, Landserf and gvSIG are to name a few. Here we restrict our discussion to QGIS which is robust and user friendly. To know more about open source GIS applications go to the link given bellow.

More about Open Source GIS software

QGIS (Previously known as Quantum GIS)

        QGIS is a cross-platform, free and open-source Geographic Information System (GIS) application that provides geospatial data viewing, editing, and analysis capabilities. It is licensed under the GNU General Public License and is an official project of the Open-Source Geospatial Foundation (OSGeo). It is a cross-platform application since it runs on Linux, Unix, Mac, OSX, Windows and even on mobiles. To download QGIS in your system go to the following link. 

Download QGIS

        On clicking the above given link you will be directed to the official page of QGIS project. Click on the download button to see the download options.


        You will be directed to the download page where two options are available for you to download the software. As far as a new user is concerned, better go for the standalone installers. More advanced QGIS users can go for the OSGeo4W network installer. Again within the standalone installer version QGIS offers two options. One is the latest release  and the second one is the Long Term Release repository(LTR). The Long Term Release are development versions and are considered static and are designed for stability, enhancement and security. Hence if you are intended to work with the software for a long period, say one year or more, I personally recommend you to download the LTR version. 



        Chances are there that you may get confused about which LTR version need to be installed, the 64 bit one or 32 bit one. The answer is, it all depends on the processor of your computer. To determine  whether your computer has 64 bit or 32 bit processor, go to the link below. (Remember this link is related to Windows operating system only)


know Your processor

    After downloading the software you have to install It. To know how to install QGIS go to the following link.

Installing QGIS

        Now your QGIS is ready. You can now make wonders with geospatial data. The Important sources of spatial data will be detailed in my next post. 






Popular posts from this blog

How to Georeference in QGIS?

     One of the fundamental and preliminary work that every GIS enthusiast should learn first is georeferencing. It is one of the elementary steps in most GIS.   It is the process of taking an airphoto, or a scanned topographic map, and adding geographic information to the image so that GIS software can 'place' the image in its appropriate real world location. This process is completed by selecting pixels in the digital image and assigning them geographic coordinates.  Usually, these coordinates are obtained by doing proper field surveys and collecting coordinates with a GPS device for few easily identifiable features in the image or the map.   More frequently, an image is georeferenced to an existing image that already has embedded geographic information.   Georeferencing raster data allows it to be viewed, queried, and analyzed with other geographic data.   Georeferencing in QGIS       One of the great benefits of QGIS is the...
Read more

2.4. Raster Data

  The raster data model represents the Earth’s surface by means of an array of two-dimensional grid cells called pixels. Each pixel has an associated value, which represents the characteristics of the spatial phenomenon. These cells or pixels are used as building blocks for creating points, lines, areas, networks, and surfaces. Raster data represent points by single cells, line by sequences of neighbouring cells, and areas by collection of contiguous cells. The JPEG, BMP, and TIFF file formats are based on the raster data model. All liquid crystal display (LCD) computer monitors are based on raster technology as they are composed of a set number of rows and columns of pixels. Although pixels may be triangles, hexagons, or even octagons, square pixels are most common. Raster models are useful for storing data that varies continuously, such as an aerial photograph, a satellite image, a surface of chemical concentrations, or an elevation surface.  Elements of Raster Data Model...
Read more

2. Modelling the Real World - Data Types and Models - Vector and Raster

Image
  The Earth’s surface is really complex, and hence, it is exceedingly difficult to represent the real-world features in a Geographical Information System. So, we use to simplify the complex real-world features before we input them into GIS. This simplified features that that we input into a GIS is called an entity.             Real world features are of two basic forms: Objects and Phenomena. Objects are discrete, identifiable units that have some sort of spatial reference, usually in the form of geographic coordinates. They have well defined boundaries. For example, houses, factories, roads, rivers, or lakes. Phenomena are distributed continuously over a large area. For E.g. Terrain, temperature, rainfall. In GIS, the real world is represented in these two basic forms. Thus, there are two distinct approaches of representing the real world in geographic databases. These two models that help to represent complex earth’s surfac...
Read more