GUS: 0262Fundamentals of GIS

Lecture Presentation 8:

Data Input and Editing

Jeremy Mennis

Department of Geography and Urban Studies

Temple University

Raster Data Input

1. Vector to Raster Conversion

2. Scanned Graphics

3. Classified Remotely Sensed Imagery

4. Interpolation from Point Data

Raster to Vector Conversion

Scanned Graphics

Classified RS Imagery

Interpolation from Point Data

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Vector Data Input

1. Raster to Vector Conversion

2. Scanned Graphics (Scan Digitizing)

3. Data Collection from the Field

4. Manual Vector Digitizing

Scanned Graphics (Scan Digitizing)

1. Drum scanner scans in map image

2. Specialized software ‘extracts’ point, line, and area features

3. Very expensive and susceptible to errors when map is ‘dirty’

Field Data Collection

Field Data Collection

Manual Vector Digitizing Tablet

Manual Vector Digitizing Puck

Manual Vector Digitizing

1. Prepare map sheet

2. Digitize the coverage

3. Identify and correct digitizing errors

4. Build topology

5. Identify and correct topology errors

6. Assign attributes

7. Identify and correct attribute errors

Manual Vector Digitizing Process

Manual Vector Digitizing Preparation

1. Map quality?

2. Separations?

3. Folds and wrinkles in the map?

4. Transfer to mylar ?

Manual Vector Digitizing Preparation

Manual Vector Digitizing Registration

Manual Vector Digitizing Process

1. Fuzzy tolerance.

2. Try to capture the necessary accuracy with minimum number of data points.

Vector Data Editing

Vector digitizing errors

1. entity error (positional error)

2. attribute error

3. entity-attribute error

Undershoots/Overshoots

Weird Polygons

Missing node

Pseudonodes

pseudonode

Polygon Label Errors

Sliver Polygons

Edge Matching