Vectors and Rasters


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Vectors and Rasters

  1. 1. Vectors and Rasters
  2. 2. Benefits of Vector Data <ul><li>Vector Model can store individual features such as roads and parcels with a high degree of precision </li></ul>
  3. 3. Benefits of Vector Data <ul><li>Vector Model’s linked attribute table provides great flexibility in the number and type of attributes which can be stored about each feature </li></ul>
  4. 4. Benefits of Vector Data <ul><li>The vector model is ideally suited to mapmaking because of the high precision and detail of features which can be obtained </li></ul>
  5. 5. Benefits of Vector Data <ul><li>Vector data is a compact way of storing data, typically requiring 1/10 th of the space of a raster with similar information </li></ul>
  6. 6. Benefits of Vector Data <ul><li>Projection of vectors from one coordinate system to another is faster than rasters </li></ul>
  7. 7. Benefits of Vector Data <ul><li>Vector model is ideally suited to certain types of analysis problems, such as </li></ul><ul><ul><li>determining perimeters and area </li></ul></ul><ul><ul><li>detecting adjacency of features, and </li></ul></ul><ul><ul><li>modeling flow through networks </li></ul></ul>
  8. 8. Drawbacks of Vector Data <ul><li>Vector data is poorly adapted to storing continuously varying surfaces like elevation or precipitation </li></ul>
  9. 9. Drawbacks of Vector Data <ul><li>It is difficult to calculate information from contours such as slope, flow direction, and aspect with vector data </li></ul>
  10. 10. Drawbacks of Vector Data <ul><li>Some types of analysis take longer to perform with vectors </li></ul>
  11. 11. Benefits of Raster Data <ul><li>Raster data is ideal for storing continuously and rapidly changing discontinuous information because each cell can have a value completely different from its neighbors </li></ul>
  12. 12. Benefits of Raster Data <ul><li>Many analyses are simple and fast to perform and an extensive set of analysis tools for rasters far outstrips those available for vectors </li></ul>
  13. 13. Benefits of Raster Data <ul><li>Raster data has access to an analysis method called map algebra, in which maps can be used as apart of algebraic expressions </li></ul>
  14. 14. Drawbacks of Raster Data <ul><li>Raster data suffer from trade-offs between precision and storage space to a greater extent than vectors do </li></ul><ul><li>If rasters are very precise they need to take up a large amount of storage space. </li></ul>
  15. 15. Drawbacks of Raster Data <ul><li>Raster data has a poor ability to store attributes </li></ul><ul><li>Raster file is an array of cells with numeric values and each cell has only one value </li></ul><ul><li>To store both geology and infiltration values for an area requires storing two separate rasters </li></ul>
  16. 16. GO PLAY <ul><li>Practice these vocabulary with Purpose Games “Price Ch1 V vs R” found here: </li></ul>
  17. 17. SOURCE <ul><li>All this vocabulary comes from: </li></ul><ul><li>Price, Maribeth. Mastering ArcGIS. McGraw-Hill; 3 edition. 2007. </li></ul>