GUS: 0262 Fundamentals of GIS

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GUS 0262Fundamentals of GIS

• Lecture Presentation 8
• Data Input and Editing
• Jeremy Mennis
• Department of Geography and Urban Studies
• Temple University

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Raster Data Input

• Vector to Raster Conversion
• Scanned Graphics
• Classified Remotely Sensed Imagery
• Interpolation from Point Data

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Raster to Vector Conversion
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Scanned Graphics
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Classified RS Imagery
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Interpolation from Point Data
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Vector Data Input

• Raster to Vector Conversion
• Scanned Graphics (Scan Digitizing)
• Data Collection from the Field
• Manual Vector Digitizing

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Scanned Graphics (Scan Digitizing)

• Drum scanner scans in map image
• Specialized software extracts point, line, and
  area features
• Very expensive and susceptible to errors when map
  is dirty

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Field Data Collection
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Field Data Collection
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Manual Vector Digitizing Tablet
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Manual Vector Digitizing Puck
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Manual Vector Digitizing
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Manual Vector Digitizing Process

• Prepare map sheet
• Digitize the coverage
• Identify and correct digitizing errors
• Build topology
• Identify and correct topology errors
• Assign attributes
• Identify and correct attribute errors

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Manual Vector Digitizing Preparation
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Manual Vector Digitizing Preparation

• Map quality?
• Separations?
• Folds and wrinkles in the map?
• Transfer to mylar ?

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Manual Vector Digitizing Registration
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Manual Vector Digitizing Process

• Fuzzy tolerance.
• Try to capture the necessary accuracy with
  minimum number of data points.

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Vector Data Editing

• Vector digitizing errors
• entity error (positional error)
• attribute error
• entity-attribute error

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Undershoots/Overshoots
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Weird Polygons
Missing node
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Pseudonodes
pseudonode
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Polygon Label Errors
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Sliver Polygons
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Edge Matching