Linear referencing an introduction
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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 referencing an introduction

Linear ReferencingAn Introduction

Heather McCracken & Derek LawESRI Redlands

UC 2009 Tech Sessions


Outline

Outline

  • Fundamental concepts

  • Terminology in ArcGIS

  • Query & analysis operations

  • Creating & maintaining routes

  • Summary

UC 2007 Tech Sessions


Outline1

Outline

  • Fundamental concepts

    • Define linear referencing

    • Application examples

  • Terminology in ArcGIS

  • Query & analysis operations

  • Creating & maintaining routes

  • Summary

UC 2007 Tech Sessions


What is linear referencing

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


Why use linear referencing

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


Features using a linear system of measure

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


Features containing one to many relationships

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


Features containing frequently segmented data

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


Outline2

Outline

  • Fundamental concepts

  • Terminology in ArcGIS

    • Routes

    • Measures

    • Events

    • Dynamic segmentation

  • Query & analysis operations

  • Creating & maintaining routes

  • Summary

UC 2007 Tech Sessions


Routes

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


Route geometry and what can they model

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

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


Measures

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


Route locations

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

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


Point event tables

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


Line event tables

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


Dynamic segmentation

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

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


Routes measures events dynamic segmentation

Demo 1

Routes, measures, events& dynamic segmentation

UC 2007 Tech Sessions


Outline3

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 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


Hatching

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

Route event analysis tools

  • Overlay events

  • Dissolve/concatenate events

  • Transform events

  • Locate points & polygonsalong routes

UC 2007 Tech Sessions


Overlay events

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

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

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


Locate points along routes

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


Locate polygons along routes

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


Find identify route locations route event analysis

Demo 2

Find & identify route locationsRoute event analysis

UC 2007 Tech Sessions


Outline4

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

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


Create a route feature class from scratch

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


Create a route feature class from existing lines

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


Calibrate route feature class

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


Editing routes

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


Create a route feature class then calibrate its m values

Demo 3

Create a route feature class,then calibrate its M values

UC 2007 Tech Sessions


Summary

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

Questions?

UC 2007 Tech Sessions


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