1. Linear Referencing An Introduction Heather McCracken & Derek Law ESRI Redlands UC 2009 Tech Sessions 1

2. Outline Fundamental conceptsFundamental concepts Terminology in ArcGISTerminology in ArcGIS Query & analysis operationsQuery & analysis operations Creating & maintaining routesCreating & maintaining routes SummarySummary UC 2007 Tech Sessions 2

3. Outline Fundamental conceptsFundamental concepts –Define linear referencing –Application examples Terminology in ArcGISTerminology in ArcGIS Query & analysis operationsQuery & analysis operations Creating & maintaining routesCreating & maintaining routes SummarySummary UC 2007 Tech Sessions 3

4. What is linear referencing? Method of storing geographic features by using relative positions along a measured line featureMethod of storing geographic features by using relative positions along a measured line feature UC 2007 Tech Sessions 4 A307 is 100 miles long. Where is mile 60? B7 A307 A45 D23 F478 A

5. Why use linear referencing? Intuitive way to model relative locations along linear featuresIntuitive way to model relative locations along linear features –E.g., The concrete road surface starts at mile 5, NOT The concrete road surface starts at 30 o 40’25’’N, 96 o 22’32’’W Enables the association of multiple sets of attributes to portions of linear features without segmenting the underlying line each time attribute values changeEnables the association of multiple sets of attributes to portions of linear features without segmenting the underlying line each time attribute values change UC 2007 Tech Sessions 5 mile 5 30 o 40’25’’N, 96 o 22’32’’W  A

6. Features using a linear system of measure Feature’s location determined using a linear system of measure values, instead of using x,y coordinatesFeature’s location determined using a linear system of measure values, instead of using x,y coordinates UC 2007 Tech Sessions 6 Main St 15 406080 95 20 Accident occurred 50 meters along Main St.

7. Features containing one-to-many relationships Two or more pieces of information associated with the same location on a lineTwo or more pieces of information associated with the same location on a line UC 2007 Tech Sessions 7 Railroad Accidents Speed 45354555 0 20 40 60 80 100 River Salmon habitat Gradient Rapid Slow Coho Coho/King 0100 200 300 400 500 600 Transportation Natural resources

8. Features containing frequently segmented data Some types of features have attributes that change frequentlySome types of features have attributes that change frequently UC 2007 Tech Sessions 8 concreteasphalt Material Quality fair goodpoor Main St. 15 406080 95 20

9. Outline Fundamental conceptsFundamental concepts Terminology in ArcGISTerminology in ArcGIS –Routes –Measures –Events –Dynamic segmentation Query & analysis operationsQuery & analysis operations Creating & maintaining routesCreating & maintaining routes SummarySummary UC 2007 Tech Sessions 9

10. Routes Linear features – in a polyline feature classLinear features – in a polyline feature class Must have an identifier & measurement systemMust have an identifier & measurement system Store in a geodatabase, shapefile, or coverageStore in a geodatabase, shapefile, or coverage UC 2007 Tech Sessions 10 Linear feature Unique identifier Route 711081

11. Route geometry and what can they model Route geometryRoute geometry Routes can modelRoutes can model UC 2007 Tech Sessions 11 Single part polylineMulti-part polyline Looping 180-degree turnsBranching

12. Routes in ArcMap Layer properties > Route tabLayer properties > Route tab Route IdentifierRoute Identifier –Uniquely identifies each route –Used by all other linear referencing dialogs in ArcGIS UC 2007 Tech Sessions 12

13. Measures The distance along a route from an originThe 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 coordinatesDo not have to be the same units as the x,y coordinates –Can increase, remain constant, or decrease Route vertices store measure values (M)Route vertices store measure values (M) NaN (unknown) measures may existNaN (unknown) measures may exist –Not a Number UC 2007 Tech Sessions 13 M at every vertex 0.0 1.2 NaN 3.7 4.8 4.2

14. Route locations Use a route identifier to locate the appropriate routeUse a route identifier to locate the appropriate route 2 types2 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 14 I10 Accident occurred at mile 23 Kenai River Salmon found between mile 10 and mile 20

15. Event tables Route locations thematically stored in tables are called “route events” or simply “events”Route locations thematically stored in tables are called “route events” or simply “events” 2 types2 types –Point event table E.g., Accidents, Sample sitesE.g., Accidents, Sample sites –Line event table E.g., Pavement conditions, Riverbank compositionE.g., Pavement conditions, Riverbank composition An event can be any type of table supported by ArcGISAn event can be any type of table supported by ArcGIS UC 2007 Tech Sessions 15

16. Point event tables Two required fieldsTwo required fields –Route ID identifies route on which event is located –Measure is the event’s location on the route Other attributes about the eventOther attributes about the event UC 2007 Tech Sessions 16 Route locationAttributes Route 1 4 14 34 45 53 0 60

17. Line event tables Three required fieldsThree 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 eventOther attributes about the event UC 2007 Tech Sessions 17 Route locationAttributes Route 48 0 25 0 60A

18. Dynamic segmentation Computing the location of events on routesComputing the location of events on routes –Event locations can change dynamically Locations are interpolatedLocations are interpolated Use the MakeRouteEventLayer GP toolUse the MakeRouteEventLayer GP tool UC 2007 Tech Sessions 18 A30710.2 A307 F478 A45 25.6 2.5 9.5 3.2 7.1 1 1 0 3 2 4 4 ACCTYPEMILE 6 5 4 3 2 1 0 OIDRKEY 15.5 A45 A307 B7 D23 F478

19. Event layers are feature layers Created by the dynamic segmentation processCreated by the dynamic segmentation process –Underlying route is not fragmented Event layers behave just like other feature layersEvent 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 19

20. Routes, measures, events & dynamic segmentation UC 2007 Tech Sessions 20 Demo 1

21. Outline Fundamental conceptsFundamental concepts Terminology in ArcGISTerminology in ArcGIS Query & analysis operationsQuery & analysis operations –Route query –Route symbolization options –Route events analysis Creating & maintaining routesCreating & maintaining routes SummarySummary UC 2007 Tech Sessions 21

22. Find and Identify route locations Find: Query a map using a route location UC 2007 Tech Sessions 22 Identify Route Locations: Click on map to determine route locations A Route: 13000C00158 Measure: 0.5

23. Hatching Line or point marker symbols placed at an interval along a routeLine or point marker symbols placed at an interval along a route –Distance E.g., meters, feetE.g., meters, feet –Non-distance E.g, sample sitesE.g, sample sites Create & modify hatch styles via style managerCreate & modify hatch styles via style manager Import hatches from a layer file (.lyr)Import hatches from a layer file (.lyr) Convert hatches to graphicsConvert hatches to graphics UC 2007 Tech Sessions 23 Seismic lines HatchHatch

24. Route event analysis tools Overlay eventsOverlay events Dissolve/concatenate eventsDissolve/concatenate events Transform eventsTransform events Locate points & polygons along routesLocate points & polygons along routes UC 2007 Tech Sessions 24

25. Overlay events Logical union or intersection of two input event tablesLogical 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 UC 2007 Tech Sessions 25 Accident count Speed limit Pavement type Skid values Asphalt 354555 453565 AsphaltConcrete 34 3032 25 Result GIS Query: Accident count > 50 Speed limit = 65 Pavement = Concrete Skid value >= 30 A

26. Dissolve/concatenate events UC 2007 Tech Sessions 26 Concatenate: remove redundant information from a tableConcatenate: remove redundant information from a table Dissolve: split tables having more than one descriptive attributeDissolve: split tables having more than one descriptive attribute

27. Transform events Transforms event measures from one route feature class to anotherTransforms 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 tableCreates a new event table Can update events after road realignmentsCan update events after road realignments UC 2007 Tech Sessions 27

28. Locate points along routes Create a point events table by locating the points along a routeCreate a point events table by locating the points along a route Preserves point attributesPreserves point attributes Route-to-point distance can be createdRoute-to-point distance can be created UC 2007 Tech Sessions 28 Route location Point attributes Optional distance field

29. Locate polygons along routes Creates a line events table from the intersection of routes with polygonsCreates a line events table from the intersection of routes with polygons Preserves polygon attributesPreserves polygon attributes UC 2007 Tech Sessions 29 Route locationPolygon attributes

30. Find & identify route locations Route event analysis UC 2007 Tech Sessions 30 Demo 2

31. Outline Fundamental conceptsFundamental concepts Terminology in ArcGISTerminology in ArcGIS Query & analysis operationsQuery & analysis operations Creating & maintaining routesCreating & maintaining routes –Creating routes –Calibrating routes –Editing routes SummarySummary UC 2007 Tech Sessions 31

32. Creating routes Routes are created byRoutes are created by –Merging linear features based on common identifiers E.g., route IDE.g., route ID –Setting measures based on one or two fields Create routesCreate 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 MethodsMethods –ArcToolbox (CreateRoutes & CalibrateRoutes GP tools) –ArcCatalog –ArcMap UC 2007 Tech Sessions 32

33. Create a Route Feature Class from Scratch Follow standard procedures for creating a feature classFollow standard procedures for creating a feature class UC 2007 Tech Sessions 33 Enable M storage Set geometry type Define route identifier field

34. Create a route feature class from existing lines UC 2007 Tech Sessions 34 CreateRoutes GP toolCreateRoutes GP tool Input features Route ID field Output features Measure field(s) or Geometric Length Measure field(s) or Geometric Length

35. Calibrate route feature class Setting a route’s measurement systemSetting a route’s measurement system UC 2007 Tech Sessions 35 Calibrate 10 0.0 55.6 5 10 15 25 30 Points with measures Existing vertex 28.4 35.2 5 10 15 20 25 30 1.1 New vertices created with interpolated measures Existing vertex’s measure is interpolated Extrapolation A

36. Editing routes UC 2007 Tech Sessions 36 Sketch Properties Tasks for linear referencing Route Editing toolbar Define line portion Make Route Calibrate Route Edit routes just like any polylineEdit routes just like any polyline –Extend, delete, split, etc Editing toolbar A

37. Create a route feature class, then calibrate its M values UC 2007 Tech Sessions 37 Demo 3

38. Summary Fundamental conceptsFundamental concepts –Defined linear referencing and its applications Terminology in ArcGISTerminology in ArcGIS –Routes, measures, events, & dynamic segmentation Query & analysis operationsQuery & analysis operations –Simple querying, symbology, & analysis tools Creating & maintaining routesCreating & maintaining routes –How to create, calibration, & editing Please complete review surveysPlease complete review surveys UC 2007 Tech Sessions 38

39. Questions? UC 2007 Tech Sessions 39