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OVERVIEW- What is GIS?

OVERVIEW- What is GIS?. A geographic information system (GIS) integrates hardware, software, and data for capturing, managing, analyzing, and displaying all forms of geographically referenced information.

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OVERVIEW- What is GIS?

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  1. OVERVIEW- What is GIS? • A geographic information system (GIS) integrates hardware, software, and data for capturing, managing, analyzing, and displaying all forms of geographically referenced information. • GIS allows us to view, understand, question, interpret, and visualize data in many ways that reveal relationships, patterns, and trends in the form of maps, globes, reports, and charts.

  2. OVERVIEW- What is GIS? • GIS helps you answer questions and solve problems by looking at your data in a way that is quickly understood and easily shared. • GIS technology can be integrated into any enterprise information system framework.

  3. What can I do with GIS • MAP locations • MAP Quantities • MAP Densities • MAP specific Areas • MAP changes

  4. Who use GIS • GIS has demonstrated real business value, or return on investment (ROI). During the last 30 years companies, agencies, academic institutions, and governments worldwide have implemented GIS programs to take advantage of these benefits. • Business, Govt, Edu& Science, Engineering, utilities, Farming, N. Resources Mnangement.

  5. What can I do with GIS • MAP Locations >Mapping where things are lets you find places that have the features you're looking for, and to see where to take action. • Find a feature—People use maps to see where or what an individual feature is. • Finding patterns—Looking at the distribution of features on the map instead of just an individual feature, you can see patterns emerge.

  6. What can I do with GIS • MAP Quantities • People map quantities, like where the most and least are, to find places that meet their criteria and take action, or to see the relationships between places. This gives an additional level of information beyond simply mapping the locations of features.

  7. Difference Between Raster and Vector Images • Raster and vector are the two basic data structures for storing and manipulating images and graphics data on a computer

  8. RASTER • Raster image comes in the form of individual pixels, and each spatial location or resolution element has a pixel associated where the pixel value indicates the attribute, such as color, elevation, or an ID number. • Raster image is normally acquired by optical scanner, digital CCD camera and other raster imaging devices. Its spatial resolution is determined by the resolution of the acquisition device and the quality of the original data source.

  9. a raster image has to have pixels for all spatial locations, it is strictly limited by how big a spatial area it can represent. • increasing the spatial resolution by 2 times, the total size of a two-dimensional raster image will increase by 4 times

  10. VECTOR • Vector data comes in the form of points and lines, that are geometrically and mathematically associated. Points are stored using the coordinates, for example, a two-dimensional point is stored as (x, y). Lines are stored as a series of point pairs, where each pair represents a straight line segment, for example, (x1, y1) and (x2, y2) indicating a line from (x1, y1) to (x2, y2).

  11. VECTOR • vector data structure produces smaller file size than raster image because a raster image needs space for all pixels while only point coordinates are stored in vector representation. • vector data is easier than raster data to handle on a computer because it has fewer data items and it is more flexible to be adjusted for different scale, for example, a projection system in mapping application.

  12. DIGITIZING VECTOR • Although vector data structure is the choice as the primary form for handling graphical data in most GIS and CAD packages, vector data acquisition is often more difficult than raster image acquisition, because its abstract data structure, topology between objects and attributes associated.

  13. Manual digitizing • Manual digitizing using a digitizing tablet has been widely used. With this method, the operator manually traces all the lines from his hardcopy map using a pointer device and create an identical digital map on his computer. A line is digitized by collecting a series of points along the line.

  14. Use of GIS • People map quantities, like where the most and least are, to find places that meet their criteria and take action, or to see the relationships between places. This gives an additional level of information beyond simply mapping the locations of features.

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