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Linear Referencing An Introduction. Heather McCracken & Derek Law ESRI Redlands. Outline. Fundamental concepts Terminology in ArcGIS Query & analysis operations Creating & maintaining routes Summary. Outline. Fundamental concepts Define linear referencing Application examples

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Linear ReferencingAn Introduction

Heather McCracken & Derek LawESRI Redlands

UC 2009 Tech Sessions


Outline

  • Fundamental concepts

  • Terminology in ArcGIS

  • Query & analysis operations

  • Creating & maintaining routes

  • Summary

UC 2007 Tech Sessions


Outline

  • Fundamental concepts

    • Define linear referencing

    • Application examples

  • Terminology in ArcGIS

  • Query & analysis operations

  • Creating & maintaining routes

  • Summary

UC 2007 Tech Sessions


A45

D23

F478

A307

D23

B7

A307

B7

A45

F478

What is linear referencing?

  • Method of storing geographic features by usingrelative positions along a measured line feature

A307 is 100 miles long. Where is mile 60?

A

UC 2007 Tech Sessions


mile 5

30o40’25’’N, 96o22’32’’W

Why use linear referencing?

  • Intuitive way to model relative locations alonglinear features

    • E.g., The concrete road surface starts at mile 5,NOT The concrete road surface starts at 30o40’25’’N, 96o22’32’’W

  • Enables the association of multiple sets of attributes to portions of linear features without segmenting the underlying line each time attribute values change

A

UC 2007 Tech Sessions


Accident occurred 50 meters along Main St.

Main St

15

95

20

40

60

80

Features using a linear system of measure

  • Feature’s location determined using a linear system of measure values, instead of using x,y coordinates

UC 2007 Tech Sessions


Accidents

45

35

45

55

Speed

Railroad

0

40

80

20

60

100

Slow

Rapid

Gradient

Coho/King

Coho

Salmon habitat

200

400

River

600

500

0

100

300

Features containing one-to-many relationships

  • Two or more pieces of information associated with the same location on a line

Transportation

Natural resources

UC 2007 Tech Sessions


15

95

20

40

60

80

concrete

asphalt

Material

good

poor

fair

Quality

Main St.

Features containing frequently segmented data

  • Some types of features have attributes that change frequently

UC 2007 Tech Sessions


Outline

  • Fundamental concepts

  • Terminology in ArcGIS

    • Routes

    • Measures

    • Events

    • Dynamic segmentation

  • Query & analysis operations

  • Creating & maintaining routes

  • Summary

UC 2007 Tech Sessions


Route 711081

Linear feature

Unique identifier

Routes

  • Linear features – in a polyline feature class

  • Must have an identifier & measurement system

  • Store in a geodatabase, shapefile, or coverage

UC 2007 Tech Sessions


Single part polyline

Multi-part polyline

Looping

Branching

180-degree turns

Route geometry and what can they model

  • Route geometry

  • Routes can model

UC 2007 Tech Sessions


Routes in ArcMap

  • Layer properties > Route tab

  • Route Identifier

    • Uniquely identifies each route

    • Used by all other linear referencing dialogs in ArcGIS

UC 2007 Tech Sessions


4.2

1.2

3.7

4.8

NaN

0.0

M at every vertex

Measures

  • The distance along a route from an origin

    • Can be miles, meters, feet, time

      • Do not have to be the same units as the x,y coordinates

    • Can increase, remain constant, or decrease

  • Route vertices store measure values (M)

  • NaN (unknown) measures may exist

    • Not a Number

UC 2007 Tech Sessions


I10

Accident occurred at mile 23

Kenai River

Salmon found between mile 10 and mile 20

Route locations

  • Use a route identifier to locate the appropriate route

  • 2 types

    • Point (uses a single measure value)

    • Discrete location on a route

    • Line (uses from- and to- measure values)

    • Describe a portion of a route

UC 2007 Tech Sessions


Event tables

  • Route locations thematically stored in tables are called “route events” or simply “events”

  • 2 types

    • Point event table

      • E.g., Accidents, Sample sites

    • Line event table

      • E.g., Pavement conditions, Riverbank composition

  • An event can be any type of table supported by ArcGIS

UC 2007 Tech Sessions


60

53

45

Route location

Attributes

34

Route 1

14

4

0

Point event tables

  • Two required fields

    • Route ID identifies route on which event is located

    • Measure is the event’s location on the route

  • Other attributes about the event

UC 2007 Tech Sessions


60

Route 48

Route location

Attributes

25

0

0

Line event tables

  • Three required fields

    • Route ID identifies route on which event is located

    • From Measure and To Measure define beginning and end of line event

  • Other attributes about the event

A

UC 2007 Tech Sessions


A45

D23

F478

OID

RKEY

MILE

ACCTYPE

A307

0

A307

10.2

1

1

A307

15.5

1

B7

2

A307

25.6

0

3

F478

2.5

3

4

F478

9.5

2

5

A45

3.2

4

6

A45

7.1

4

Dynamic segmentation

  • Computing the location of events on routes

    • Event locations can change dynamically

      • Locations are interpolated

  • Use the MakeRouteEventLayer GP tool

UC 2007 Tech Sessions


Event layers are feature layers

  • Created by the dynamic segmentation process

    • Underlying route is not fragmented

  • Event layers behave just like other feature layers

    • Display using custom symbology

    • Perform GIS analysis

    • Save as a layer file

    • Export to feature class

UC 2007 Tech Sessions


Demo 1

Routes, measures, events& dynamic segmentation

UC 2007 Tech Sessions


Outline

  • Fundamental concepts

  • Terminology in ArcGIS

  • Query & analysis operations

    • Route query

    • Route symbolization options

    • Route events analysis

  • Creating & maintaining routes

  • Summary

UC 2007 Tech Sessions


Find and Identify route locations

Find:Query a map using a route location

Identify Route Locations: Click on map to determine route locations

Route: 13000C00158

Measure: 0.5

A

UC 2007 Tech Sessions


Seismic lines

Hatch

Hatching

  • Line or point marker symbols placed at an interval along a route

    • Distance

      • E.g., meters, feet

    • Non-distance

      • E.g, sample sites

  • Create & modify hatch styles via style manager

  • Import hatches from a layer file (.lyr)

  • Convert hatches to graphics

UC 2007 Tech Sessions


Route event analysis tools

  • Overlay events

  • Dissolve/concatenate events

  • Transform events

  • Locate points & polygonsalong routes

UC 2007 Tech Sessions


Accident count

35

45

55

25

Speed limit

35

65

45

Pavement type

Asphalt

Asphalt

Concrete

Skid values

34

30

32

Result

Overlay events

  • Logical union or intersection of two input event tables

    • Creates new event table with attributes from both tables

  • Non-geometric way of performing

    • Line-on-line, line-on-point, & point-on-point overlays

GIS Query:Accident count > 50 Speed limit = 65 Pavement = Concrete Skid value >= 30

A

UC 2007 Tech Sessions


Dissolve/concatenate events

  • Concatenate:remove redundant information from a table

  • Dissolve:split tables having more than one descriptive attribute

UC 2007 Tech Sessions


Transform events

  • Transforms event measures from one route feature class to another

    • Route feature classes can be of different measure systems (e.g., time & length)

  • Creates a new event table

  • Can update events after road realignments

UC 2007 Tech Sessions


Pointattributes

Route location

Optional distance field

Locate points along routes

  • Create a point events table by locating the points along a route

  • Preserves point attributes

  • Route-to-point distance can be created

UC 2007 Tech Sessions


Route location

Polygon attributes

Locate polygons along routes

  • Creates a line events table from the intersection of routes with polygons

  • Preserves polygon attributes

UC 2007 Tech Sessions


Demo 2

Find & identify route locationsRoute event analysis

UC 2007 Tech Sessions


Outline

  • Fundamental concepts

  • Terminology in ArcGIS

  • Query & analysis operations

  • Creating & maintaining routes

    • Creating routes

    • Calibrating routes

    • Editing routes

  • Summary

UC 2007 Tech Sessions


Creating routes

  • Routes are created by

    • Merging linear features based on common identifiers

      • E.g., route ID

    • Setting measures based on one or two fields

  • Create routes

    • By creating a new empty feature class & loading data

    • By creating a new route feature class from existing line features

    • By converting an existing route feature class

  • Methods

    • ArcToolbox (CreateRoutes & CalibrateRoutes GP tools)

    • ArcCatalog

    • ArcMap

UC 2007 Tech Sessions


Define route identifier field

Set geometry type

Enable M storage

Create a Route Feature Class from Scratch

  • Follow standard procedures for creating a feature class

UC 2007 Tech Sessions


Input features

Route ID field

Output features

Measure field(s) or

Geometric Length

Create a route feature class from existing lines

  • CreateRoutes GP tool

UC 2007 Tech Sessions


Points with measures

10

5

15

30

55.6

10

25

0.0

28.4

Existing vertex

Extrapolation

Calibrate

10

35.2

Extrapolation

15

30

5

25

20

1.1

New vertices createdwith interpolated measures

Existing vertex’s measure is interpolated

Calibrate route feature class

  • Setting a route’s measurement system

A

UC 2007 Tech Sessions


Sketch Properties

Route Editing toolbar

Define line portion

Calibrate Route

Tasks for linear referencing

Make Route

Editing routes

  • Edit routes just like any polyline

    • Extend, delete, split, etc

Editing toolbar

A

UC 2007 Tech Sessions


Demo 3

Create a route feature class,then calibrate its M values

UC 2007 Tech Sessions


Summary

  • Fundamental concepts

    • Defined linear referencing and its applications

  • Terminology in ArcGIS

    • Routes, measures, events, & dynamic segmentation

  • Query & analysis operations

    • Simple querying, symbology, & analysis tools

  • Creating & maintaining routes

    • How to create, calibration, & editing

  • Please complete review surveys

UC 2007 Tech Sessions


Questions?

UC 2007 Tech Sessions


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