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# Vectors and Rasters

## by Jessica Meyer, Volunteer / Graduate Student at Home on Sep 15, 2010

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## Vectors and RastersPresentation Transcript

• Vectors and Rasters
• Benefits of Vector Data
• Vector Model can store individual features such as roads and parcels with a high degree of precision
• Benefits of Vector Data
• Vector Model’s linked attribute table provides great flexibility in the number and type of attributes which can be stored about each feature
• Benefits of Vector Data
• The vector model is ideally suited to mapmaking because of the high precision and detail of features which can be obtained
• Benefits of Vector Data
• Vector data is a compact way of storing data, typically requiring 1/10 th of the space of a raster with similar information
• Benefits of Vector Data
• Projection of vectors from one coordinate system to another is faster than rasters
• Benefits of Vector Data
• Vector model is ideally suited to certain types of analysis problems, such as
• determining perimeters and area
• detecting adjacency of features, and
• modeling flow through networks
• Drawbacks of Vector Data
• Vector data is poorly adapted to storing continuously varying surfaces like elevation or precipitation
• Drawbacks of Vector Data
• It is difficult to calculate information from contours such as slope, flow direction, and aspect with vector data
• Drawbacks of Vector Data
• Some types of analysis take longer to perform with vectors
• Benefits of Raster Data
• Raster data is ideal for storing continuously and rapidly changing discontinuous information because each cell can have a value completely different from its neighbors
• Benefits of Raster Data
• Many analyses are simple and fast to perform and an extensive set of analysis tools for rasters far outstrips those available for vectors
• Benefits of Raster Data
• Raster data has access to an analysis method called map algebra, in which maps can be used as apart of algebraic expressions
• Drawbacks of Raster Data
• Raster data suffer from trade-offs between precision and storage space to a greater extent than vectors do
• If rasters are very precise they need to take up a large amount of storage space.
• Drawbacks of Raster Data
• Raster data has a poor ability to store attributes
• Raster file is an array of cells with numeric values and each cell has only one value
• To store both geology and infiltration values for an area requires storing two separate rasters
• GO PLAY
• Practice these vocabulary with Purpose Games “Price Ch1 V vs R” found here: http://www.purposegames.com/game/95fbfac383/info
• SOURCE
• All this vocabulary comes from:
• Price, Maribeth. Mastering ArcGIS. McGraw-Hill; 3 edition. 2007.