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Working with Routes and Linear Referencing in ArcGIS

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This presentation discusses the concepts of Linear Referencing and Routes, how to create them, and how to use them for analysis.

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Working with Routes and Linear Referencing in ArcGIS

  1. 1. 1/21 Presentation Objectives Working with Linear Referencing and Route Events Data Clean-up for Linear Features Creating and Editing Topology and Routes Analysis with Routes Copyright 2013 – John SchaefferJuniper GIS Working with Linear Referencing and Routes Developed and Presented by Juniper GIS PowerPoint available at www.junipergis.comLinks
  2. 2. 2/21 Understanding Linear Referencing Working with Linear Referencing and Routes Copyright 2013 – John SchaefferJuniper GIS Linear Referencing Basics Allows us to store location as a one-dimensional measure relative to the location along a linear feature These locations are referred to as “Events” and the process of displaying these events is called Dynamic Segmentation. 
  3. 3. 3/21 Understanding Linear Referencing Working with Linear Referencing and Routes Copyright 2013 – John SchaefferJuniper GIS Linear Referencing Basics These events can be linear, located using From and To measures, or points, located with a single measure. These events are stored in a table; with a reference to the linear feature being measured and the measure value or values.
  4. 4. 4/21 Understanding Linear Referencing Working with Linear Referencing and Routes Copyright 2013 – John SchaefferJuniper GIS Linear Referencing Basics Linear Referencing allows us to use multiple tables, locating a variety of different types of information, along the same linear feature.
  5. 5. 5/21 Understanding Linear Referencing Working with Linear Referencing and Routes Copyright 2013 – John SchaefferJuniper GIS Linear Referencing Basics Without linear referencing, we would need to split data into separate feature classes for each activity we wanted to measure. Any time you needed to edit an activity, you might need to edit several feature classes, but with linear referencing, you would just edit one table.
  6. 6. 6/21 Understanding Linear Referencing Working with Linear Referencing and Routes Copyright 2013 – John SchaefferJuniper GIS Linear Referencing Basics Another way to describe these events is as ‘Virtual Layers’ displayed as needed, within ArcMap. These events can be used in analysis similar to other layers in ArcMap. These events can be exported as actual feature classes.
  7. 7. 7/21 Understanding Linear Referencing Working with Linear Referencing and Routes Copyright 2013 – John SchaefferJuniper GIS Creating Routes Routes are a special type of linear feature class that contain direction and measure values, with the measure value, such as feet, miles, river kilometers, increasing in one direction. Shape field shows the geometry type as PolylineM. Routes can be created as shapefiles or geodatabase feature classes.
  8. 8. 8/21 Understanding Linear Referencing Working with Linear Referencing and Routes Copyright 2013 – John SchaefferJuniper GIS Creating Routes Routes can be created from an existing feature class with the Create Routes tool. This requires a field that identifies all the segments that will be an individual route. Routes need to have a defined measurement source. This can be the geometric length as calculated by ArcMap, or a field with the measured length.
  9. 9. 9/21 Understanding Linear Referencing Working with Linear Referencing and Routes Copyright 2013 – John SchaefferJuniper GIS Creating Routes Routes need to have a ‘Starting Point’ and direction. If there are existing measures ArcMap can determine start & direction of routes. If not, you can use Coordinate Priority - upper-left, lower-left, etc. - to assign a starting point and direction.
  10. 10. 10/21 Understanding Linear Referencing Working with Linear Referencing and Routes Copyright 2013 – John SchaefferJuniper GIS Creating Routes Coordinate Priority only works well if all features are going the same direction
  11. 11. 11/21 Understanding Linear Referencing Working with Linear Referencing and Routes Copyright 2013 – John SchaefferJuniper GIS Creating Routes Routes might need a measure factor if the measurement value is different from the feature’s unit value. For example, the units for a stream feature class are in meters, but we want the measurement value to be in kilometers.
  12. 12. 12/21 Understanding Linear Referencing Working with Linear Referencing and Routes Copyright 2013 – John SchaefferJuniper GIS Creating Routes Routes can deal with spatial gaps, or how you measure gaps in segments. The default is to ignore the gaps and to continue the measurement values as if the gap did not exist. If unchecked, then a straight-line distance is used to adjust the route measurements for the gap.
  13. 13. 13/21 Understanding Linear Referencing Working with Linear Referencing and Routes Copyright 2013 – John SchaefferJuniper GIS Creating Routes Routes can also be created from individual line segments with the Make Route tool. This is done in an editing session and requires an existing route feature class as a template. The route feature class can be an empty feature class or could be a feature class that already contains routes.
  14. 14. 14/21 Understanding Linear Referencing Working with Linear Referencing and Routes Copyright 2013 – John SchaefferJuniper GIS Creating Routes After selecting the feature or features, click on the Make Route tool and you’ll be prompted for a starting point, a measure value and a measure factor. This can be used as a quick way to ‘recreate’ routes that were created going in the wrong direction.
  15. 15. 15/21 Understanding Linear Referencing Working with Linear Referencing and Routes Copyright 2013 – John SchaefferJuniper GIS Working with Route Layers Routes are similar to other data layers and can be manipulated using layer properties. Route layers have two additional tabs. Routes Tab – used to display route measure anomalies or to see where problems might exist.
  16. 16. 16/21 Understanding Linear Referencing Working with Linear Referencing and Routes Copyright 2013 – John SchaefferJuniper GIS Working with Route Layers Hatches Tab – used to display measurement markers.
  17. 17. 17/21 Understanding Linear Referencing Working with Linear Referencing and Routes Copyright 2013 – John SchaefferJuniper GIS Displaying Route Events Once routes have been created, information in event tables that reference routes can be displayed. Events can be either point events, such as sign locations, or linear events such as change in ownership or condition over a distance.
  18. 18. 18/21 Understanding Linear Referencing Working with Linear Referencing and Routes Copyright 2013 – John SchaefferJuniper GIS Displaying Route Events This creates ‘virtual layers’ that exist in that map, that act like regular data layers, and can be exported as feature classes. If the underlying data table or routes change, the displayed data changes accordingly.
  19. 19. 19/21 Understanding Linear Referencing Working with Linear Referencing and Routes Copyright 2013 – John SchaefferJuniper GIS Displaying Route Events – Route Errors In 10, the table for route events shows all input records, even those that don’t display because of location errors. In 10.1, the table only shows “good” points. To fix this quirk, right-click the Loc_Error field; select Sort Ascending, and you will see all records, including those with errors. This is needed to find and repair errors.
  20. 20. 20/21 Understanding Linear Referencing Working with Linear Referencing and Routes Copyright 2013 – John SchaefferJuniper GIS Data Clean-up for Routes Very important to have clean linear features before you create routes. If you have ArcEditor, you can create Geodatabase Topology to check for common errors. Dangles Pseudos Overlaps Intersecting lines Multipart lines
  21. 21. 1/10 Editing and Using Routes for Analysis Working with Linear Referencing and Routes Editing Routes The most common edit to route features will be to adjust route measures. Route measures are usually based on the length calculated by GIS. If there are more accurate measurements, these can be used to adjust the measures along the entire route, or in just a small section. Errors in measurement values can also be introduced when features are extended, merged, intersected or unioned. Copyright 2013 – John SchaefferJuniper GIS
  22. 22. 2/10 Editing and Using Routes for Analysis Working with Linear Referencing and Routes Route Editing Tools Route Editing Toolbar Calibrate Route Tool – works in conjunction with the Calibrate Route Feature task. Select a route and then click on a point where you need to adjust a measure. The other measures in that route or portion of the route can then be interpolated or extrapolated as needed. Works best if you identify at least two points. Copyright 2013 – John SchaefferJuniper GIS
  23. 23. 3/10 Editing and Using Routes for Analysis Working with Linear Referencing and Routes Route Editing Tools Identify Route Locations Tool – similar to the Identify Tool, but works with routes and displays measurement values and other information on a route. This tool is very helpful when checking route measures before or after calibrating routes. This tool has to be added to the Route Editing Toolbar. Copyright 2013 – John SchaefferJuniper GIS
  24. 24. 4/10 Editing and Using Routes for Analysis Working with Linear Referencing and Routes Route Editing Tools Linear Referencing Tools The Calibrate Routes tool creates a new route feature class by calibrating an existing route feature class based on points that contain more accurate measurements. For best results the points should be on or very near the routes. Copyright 2013 – John SchaefferJuniper GIS
  25. 25. 5/10 Editing and Using Routes for Analysis Working with Linear Referencing and Routes Using Routes for Analysis Most analysis is actually based on the ‘events’ located along the route rather than the route itself. Since the event layers act as any other layer, the normal analysis tools you might use apply, as well as some of the tools in the Linear Referencing Toolset. Copyright 2013 – John SchaefferJuniper GIS
  26. 26. 6/10 Editing and Using Routes for Analysis Working with Linear Referencing and Routes Using Routes for Analysis Dissolve Feature Events – Creates a new event table that removes redundant information or separates event tables into separate tables when they have more than one descriptive attribute. Copyright 2013 – John SchaefferJuniper GIS
  27. 27. 7/10 Editing and Using Routes for Analysis Working with Linear Referencing and Routes Using Routes for Analysis Overlay Route Events Overlays two event tables to create an output event table that represents the union or intersection of the input. Copyright 2013 – John SchaefferJuniper GIS
  28. 28. 8/10 Editing and Using Routes for Analysis Working with Linear Referencing and Routes Using Routes for Analysis Transform Route Events Creates a new event table by transforming the measures of events from one route reference to another route reference. This is useful if you need to transfer measures or route ids from one event table to another. Copyright 2013 – John SchaefferJuniper GIS
  29. 29. 9/10 Editing and Using Routes for Analysis Working with Linear Referencing and Routes Using Routes for Analysis Locate Features Along Routes Creates a new event table with route and measure information by intersecting input features (point, line, or polygon) with routes. Copyright 2013 – John SchaefferJuniper GIS
  30. 30. http://www.junipergis.com/gis-links/presentations/ Linear Referencing Editing Tips Spatial Analyst and Raster Analysis Geodatabase Topology Suitability Modeling ModelBuilder Using the Query Builder Projections on U Tube Other Presentations 72/72 Working with Linear Referencing and Routes

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