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# Linear referencing 2014

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### Linear referencing 2014

1. 1. LINEAR REFERENCING In Arc GIS Version 9.3
2. 2. Institute of Geology, University of the Punjab Tuesday, January 28, 2014 Linear Referencing Presented To: Sir. Numan Ashraf Submitted By: Abdul Haseeb Ahson Atiqa Ijaz Khan 01 02 2
3. 3. Institute of Geology, University of the Punjab Table Of Contents 1. What is Linear Referencing? 2. Implementation in Arc GIS 3. Why Use Linear Referencing? 4. Route 5. Event Table 6. Dynamic Segmentation 7. Working with Arc GIS 8. Summary 9. References Tuesday, January 28, 2014 3
4. 4. 4 What Is Linear Referencing? 1. “It is the method of storing geographic locations by using relative positions along a measured linear feature.” 2. In linear referencing, location is given in terms of: a. a known line feature and a position, b. or measure, along the feature. 3. The method provides the ability to uniquely identify positions along lines without explicit x,y coordinates. Institute of Geology, University of the Punjab Tuesday, January 28, 2014
5. 5. 5 Modeling Of Data In Arc GIS 1. In Arc GIS, geographic data is stored in three ways: a. As a collection of features in a Vector format. b. As an array of cells in Raster format. c. As a set of triangulated points in TIN. Talking about the Vector Data Format Only… ! Institute of Geology, University of the Punjab Tuesday, January 28, 2014
6. 6. 6 Why Use Linear Referencing? 1. As we know that In the vector format, each feature has a geometry associated with it. Each geometry is composed of two dimensional (x,y) or three dimensional (x,y,z) coordinates. 2. Many organizations collect data about the linear features as a point location along the line as an alternative to expressing the location using xy-coordinates. 3. While the vector data is useful for the representation of the “Static Data”, like, water bodies, parcel boundaries etc. 4. Also used to associate the multiple-attributes to a set of linear features, without splitting. Institute of Geology, University of the Punjab Tuesday, January 28, 2014
7. 7. 7  mile 5 30o40’25’’N, 96o22’32’’W  • E.g., The concrete road surface starts at mile NOT The concrete road surface starts at 30o40’25’’N, 96o22’32’’W. Institute of Geology, University of the Punjab 5, Tuesday, January 28, 2014
8. 8. 8 Accident occurred 50 meters along Main St. Main St 15 20 40 60 80 95 • Features using a linear system of measure. • Feature’s location determined using a linear system of measure values, instead of using x,y coordinates. Institute of Geology, University of the Punjab Tuesday, January 28, 2014
9. 9. 9 • Features containing frequently segmented data. • Some types of features have attributes that change frequently. Institute of Geology, University of the Punjab Tuesday, January 28, 2014
10. 10. 10 Implementation In Arc GIS 1. Primary Data Types: a. Route Feature Classes b. Event Tables 2. Process: Dynamic Segmentation a. Line feature from a route feature class b. Events from event table are located in line feature Institute of Geology, University of the Punjab Tuesday, January 28, 2014
11. 11. 11 Route 2. “A Route is a path through a network.” 3. Routes are stored in a feature class whose geometry type is “Polyline”. 4. By definition: “A polyline is an ordered collection of paths.” 5. Polylines with measures are stored as polyline-M type. 6. Measure values are ONLY stored in Vertex (for Polyline also). Between them, the data is interpolated. Institute of Geology, University of the Punjab Tuesday, January 28, 2014
12. 12. 12 1. “A route is a linear feature that has: a. A unique identifier and b. A measurement.” Route 711081 Linear feature Institute of Geology, University of the Punjab Unique identifier Tuesday, January 28, 2014
13. 13. 13 Measurements of Route 1. “Measures are the Distance along a Route from an Origin” 2. The measures are independent of the underlying feature geometry. a. If the data is in UTM, then its measure values can be in feet or inches etc 3. They can, along a route, increase, decrease, or remain the same. 4. The measures are stored as long binary data (i.e. x,y,m) OR (i.e. x,y,z, and m) 5. By definition, the measures are common to all routes in the feature class. Institute of Geology, University of the Punjab Tuesday, January 28, 2014
14. 14. 14 Transportation Accidents 45 Speed Railroad 0 35 20 45 40 60 55 80 100 • Features containing one-to-many relationships • Two or more pieces of information associated with the same location on a line Institute of Geology, University of the Punjab Tuesday, January 28, 2014
15. 15. 15 Event Tables 1. Events are geographic location stored in “Tabular” rather than “Spatial” form. 2. Event types include address events, route events, xy events, and temporal events. 3. Specifically, route events can be linear, continuous, or point features occurring along a base route system. 4. Route locations thematically stored in tables are called “Route Events” or simply “Events”. 5. Two types: • Point Event Table • E.g., Accidents, Sample sites • Line Event Table • E.g., Pavement conditions, Riverbank composition Institute of Geology, University of the Punjab Tuesday, January 28, 2014
16. 16. 16 I10 Accident occurred at mile 23 Kenai River Salmon found between mile 10 and mile 20 Institute of Geology, University of the Punjab Tuesday, January 28, 2014
17. 17. 17 Point Event Tables 1. “A feature that occurs at a precise point location along a route and uses a single measure value.” 60 53 2. Two required fields: 45 • Route ID identifies route on which event is located • Measure is the event’s location on the route 34 Route location Attributes 3. Other attributes about the event. Route 1 14 4 0 Institute of Geology, University of the Punjab Tuesday, January 28, 2014
18. 18. 18 Institute of Geology, University of the Punjab Tuesday, January 28, 2014
19. 19. 19 Line Event Tables 1. “Linear events are used to model portions of routes and are stored in tables.” 2. Three required fields • Route ID identifies route on which event is located • From Measure and To Measure define beginning and end of line event 3. Other attributes about the event Route location 60 Route 48 Attributes 25 0 Institute of Geology, University of the Punjab Tuesday, January 28, 2014 0
20. 20. 20 Institute of Geology, University of the Punjab Tuesday, January 28, 2014
21. 21. 21 1. A “Point event” describes a discrete location along a route (a point), whereas 2. A “Line event” describes a portion of a route (a line). 3. All of the data is important, but to segment the linear data (geometry) to create a “Break” or “Segment” every time a change occurs is not an efficient way to store or manage the dataset. This Lead us to the Concept of “Dynamic Segmentation” Institute of Geology, University of the Punjab Tuesday, January 28, 2014
22. 22. 22 Dynamic Segmentation 1. There are Two requirements for dynamic segmentation: a. A table of events that include a unique identifier and associated measures, b. And a collection of linear features that include a unique identifier and a measurement system. 2. Dynamic segmentation is the process of computing map location of events. Events are stored and managed in an event table. The linear referencing measurement system is used to display events on a map. Institute of Geology, University of the Punjab Tuesday, January 28, 2014
23. 23. 23 Institute of Geology, University of the Punjab Tuesday, January 28, 2014
24. 24. 24 Benefits of Dynamic Segmentation 1. Multiple sets of attributes can be associated with any portion of an existing linear feature. 2. More importantly, attributes may be displayed, queried, edited and analyzed without affecting the underlying linear feature geometry 3. The use of linear referencing permits you to dynamically locate a segment, without the need to edit feature data geometry resulting in more efficient data management. Institute of Geology, University of the Punjab Tuesday, January 28, 2014
25. 25. 25 Working with Arc GIS 9.3 1. Following are the sub-set tools in Arc GIS 9.3 Toolbox for Linear Referencing Tools: a. Calibrate Routes b. Create Routes c. Dissolve Route Events d. Locate Features along the Routes e. Make Route Event Layer f. Overlay Route Events g. Transform Route Events Institute of Geology, University of the Punjab Tuesday, January 28, 2014
26. 26. Institute of Geology, University of the Punjab Tuesday, January 28, 2014 Data for Practice 1. Utah (USA) Road And Highway System 2. In Geo-database Fomrat 3. Coordinate System: NAD 1983 26
27. 27. 27 Create Routes * So to have the options of Route Properties Institute of Geology, University of the Punjab Tuesday, January 28, 2014
28. 28. 28 Institute of Geology, University of the Punjab Tuesday, January 28, 2014
29. 29. 29 Calibrate Routes * For just to have an update Institute of Geology, University of the Punjab Tuesday, January 28, 2014
30. 30. 30 Institute of Geology, University of the Punjab Tuesday, January 28, 2014
31. 31. 31 Institute of Geology, University of the Punjab Tuesday, January 28, 2014
32. 32. 32 Institute of Geology, University of the Punjab Tuesday, January 28, 2014
33. 33. Dissolve Route Events 33 * For division of event table Institute of Geology, University of the Punjab Tuesday, January 28, 2014
34. 34. 34 Institute of Geology, University of the Punjab Tuesday, January 28, 2014
35. 35. Locate Feature Along Route 35 * Pick those points that intersects the linear feature Institute of Geology, University of the Punjab Tuesday, January 28, 2014
36. 36. 36 Output Input Points Input Lines Institute of Geology, University of the Punjab Tuesday, January 28, 2014
37. 37. Make Route Event Layer Institute of Geology, University of the Punjab 37 Tuesday, January 28, 2014
38. 38. 38 Institute of Geology, University of the Punjab Tuesday, January 28, 2014
39. 39. Overlay Events 39 * Overlays two event table on the basis of their unique ID Institute of Geology, University of the Punjab Tuesday, January 28, 2014
40. 40. 40 Input_1 Input_2 Overlay Output Institute of Geology, University of the Punjab Tuesday, January 28, 2014
41. 41. Transform Route Events Institute of Geology, University of the Punjab 41 Tuesday, January 28, 2014
42. 42. 42 Sample_Example Institute of Geology, University of the Punjab Tuesday, January 28, 2014
43. 43. 43 Summary Tool Input_1 Input_2 Input_3 Output Create Route .shp / .dbf - - Route .shp /.dbf Calibrate Route Route .shp /.dbf Point/line .shp /.dbf Dissolve Route Events Table Unique ID Dissolve Field Event Table Make Route Event Layer Route .shp /.dbf Event Table - Table & .lyr Locate Feature Along the Route .shp / .dbf Route .shp /.dbf Event Table OR .dbf Overlay Route Event Event Table Event Table Event Table Transform Route Events Event Table .shp / .dbf Institute of Geology, University of the Punjab .shp /.dbf .sh / .dbf Event table Tuesday, January 28, 2014
44. 44. Tuesday, January 28, 2014 Institute of Geology, University of the Punjab References 1. 2. 3. 4. 5. Linear Referencing in Arc GIS Tutorial PDF Linear Referencing by: Christopher Grasteit, Technical Marketing Working with Linear Referencing and Routes, by: www.junipergis.comlinks www.help.arcgis.com www.rnr/geog420/520 (Spring 2008) 44
45. 45. Institute of Geology, University of the Punjab Tuesday, January 28, 2014 45