A Quick Introduction to Linear Referencing

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A Quick Introduction toLinear Referencing

• Allan Pickering, GISP

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What is Linear Referencing?
Introduction What is LR? Why use LR? How to
use Example Considerations Find More Conclusion
Reference Systems
Cartesian Coordinates
(3,2)
(0,0)
Latitude Longitude project to Cartesian
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What is Linear Referencing?
Introduction What is LR? Why use LR? How to
use Example Considerations Find More Conclusion
Linear Feature
An Example
Distance Along
Im at mile marker 66 on State Highway 112.
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What is Linear Referencing?
Introduction What is LR? Why use LR? How to
use Example Considerations Find More Conclusion

• Reference System
• Refers to a things place
• Linear Feature
• or Route
• Distance Along
• called a Measure or M Value

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Why Use Linear Referencing?
Introduction What is LR? Why use LR? How to
use Example Considerations Find More Conclusion

• Verbal method
• Avoids segmentation
• Historical data

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Why Use Linear Referencing?
Introduction What is LR? Why use LR? How to
use Example Considerations Find More Conclusion
Features with Static Segmentation
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Why Use Linear Referencing?
Introduction What is LR? Why use LR? How to
use Example Considerations Find More Conclusion
segment
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Why Use Linear Referencing?
Introduction What is LR? Why use LR? How to
use Example Considerations Find More Conclusion

• Dynamic Segmentation

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How to use
Introduction What is LR? Why use LR? How to
use Example Considerations Find More Conclusion

• Requires two components

Events
Route
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How to use
Introduction What is LR? Why use LR? How to
use Example Considerations Find More Conclusion

• Routes

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3
5
2

• Calibration
• M-Enabled
• Automatic Methods

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How to use
Introduction What is LR? Why use LR? How to
use Example Considerations Find More Conclusion

• Events

Point Events
Line Events
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How to use
Introduction What is LR? Why use LR? How to
use Example Considerations Find More Conclusion

• Dynamic Segmentation

B
A
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How to use
Introduction What is LR? Why use LR? How to
use Example Considerations Find More Conclusion

• Route Event Layers can
• be symbolized labeled
• be queried
• participate in geoprocessing
• be exported
• be transformed
• LRS A to LRS B
• coordinates to LRS
• event manipulation

dissolve
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Example
Introduction What is LR? Why use LR? How to
use Example Considerations Find More Conclusion
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Considerations
Introduction What is LR? Why use LR? How to
use Example Considerations Find More Conclusion

• Event Locating Errors

M10.1 Route BB M -1 to M 2 M 8 to M 11 M 11 to M
12 Route AA
Route Measure Not Found Route Not Found Partial
Match for the From-Measure Partial Match for the
To-Measure Measure Extent out of Route Measure
Range Route Without Measure
0.0
Route BB?
Route AA
10.0
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Considerations
Introduction What is LR? Why use LR? How to
use Example Considerations Find More Conclusion

• Routes and Route Events can not exist
  independently.
• Edits on one may affect the other.

604.0
614.0
Route AAA
0.0
10.0
Route A
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Considerations
Introduction What is LR? Why use LR? How to
use Example Considerations Find More Conclusion

• Accuracy?
• Spatial Accuracy of linear feature
• Accuracy of M Values
• Accuracy of Events M Values

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Supported Platforms
Introduction What is LR? Why use LR? How to
use Example Considerations Find More Conclusion

• ArcGIS
• Oracle, DB2
• GeoMedia
• AutoCAD
• GRASS PostGIS
• Included in Data Model for Transportation (GIS-T)

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Where can you find more?
Introduction What is LR? Why use LR? How to
use Example Considerations Find More Conclusion

• webhelp.esri.com
• search for linear referencing on the ESRI
  support page
• Linear Referencing and Dynamic Segmentation in
  ArcGIS 8.1
• Linear Referencing in ArcGIS Practical
  Considerations for the Development of an
  Enterprisewide GIS

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Questions?

• Allan Pickering
• allan.pickering_at_bartwest.com
• presentation will be posted on NCTGITA page
• www.bartwest.com