Methods of representing geographic space - PowerPoint PPT Presentation

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Methods of representing geographic space

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  1. Methods of representing geographic space Raster Model Vector Model

  2. Map as an Abstraction of space: • Spatial features can be represented as points, lines and area(polygons). • Some objects are selected for inclusion and another not spatial feature and it have attributes as 1- simplified 2-aggregated 3- classified. • When the geographies want to enter the data to GIS, they have some decision need to made based upon to can entered it to computer.

  3. The definition: • Raster Models: It is that features made of cells and each cells related with another cells. • Vector Models: It is that features included points, lines and polygons and their data is spaghetti.

  4. Vector Models • It is represent by (x , y) coordinates. • Vector model take less storage. • Example for vector model is digitization. • We take long time when make vector model.

  5. Raster models • It is represent by (pixel or cell) • It is take more storage. • Example for raster model is scanning. • We take short time when make Raster model.

  6. Geographic Representations • CELLS: a representation of geographic data on rows and columns . • PIXELS: a group of points with a color value but no data related to others

  7. Raster and vector representation • Raster representation Vectorrepresentation

  8. Continue

  9. RasterData: Advantages and Disadvantages

  10. VectorData: Advantages and Disadvantages

  11. Grid data (cells)

  12. Satellite image (pixels)

  13. Vector Vs. Raster