Optimum route finder to the Point of Interest through public

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Index

• pgRouting on PostgreSQL

Introduction

Installation

Template Creation and Use

Topological Structure

Core Features

Public Transit Implementation

(Application Specific)

Why routing on PostgreSQL?

• PostGIS ships with a Shape file loader an dumper

• Various file types (Shape, MapInfo, DGN, GML, ...) can be read, converted and inserted to a PostGIS database using the OGC libraries

• A PostGIS Feature Table can be used as data source for a growing variety of map and feature server software like UMN MapServer,

GeoServer, uDGI, deegree , JUMP, etc...

• The data can be accessed using standard ODBC or JDBC connectors

• Several projects have evolved around PostGIS transforming and inserting geometries from highly specialized formats like SICAD

C60, EDBS, DXF, WLDGE and many more

pgRouting :an PostgreSQL Extension

• pgRouting adds routing functionality to PostgreSQL.

• pgRouting is an extendible open-source library that provides a variety of tools for shortest path search as extension of

PostgreSQL.

• Navigation for road networks requires complex routing algorithms that support turn restrictions and even time dependent attributes.

• Routing basically requires Network topology, which contains edges and nodes.

Core Features of pgRouting

pgRouting provides functions for:

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Shortest Path Dijkstra: routing algorithm without heuristics

Shortest Path A-Star: routing for large datasets (with heuristics)

Shortest Path Shooting-Star: routing with turn restrictions (with heuristics)

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(Extras)

Traveling Salesperson Problem (TSP)

Driving Distance calculation (Isolines)

pgRouting Installation

On Ubuntu :

On Windows:

# Add pgRouting launchpad repository

sudo add-apt-repository ppa:georepublic/pgrouting sudo apt-get update

# Install pgRouting packages

sudo apt-get install gaul-devel \ postgresql-8.4-pgrouting \ postgresql-8.4-pgrouting-dd \ postgresql-8.4-pgrouting-tsp

Download pgRouting binary package from :

http://www.pgrouting.org/down load.html

Copy Share folder from binary package to :

C:/Program Files/ …

/<version>/lib/

Required Topological data structure

Nodes : points with a geographic position.

edges : represents connectivity of nodes, representing a polyline or multipolyline.

Relations : between groups of nodes, edges and other relations which can be assigned certain properties.

• Tags can be applied to nodes, edges or relations and consist of name=value pairs.

pgRouting Template Creation and Use:

To enable pgRouting functionality in a database, we need to run :

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pgRouting functions

routing_core.sql

routing_core_wrappers.sql

routing_topology.sql

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TSP functions

routing_tsp.sql routing_tsp_wrappers.sql

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Driving Distance functions

routing_dd_wrappers.sql

pgRouting: Topology Calculation

• First we have to add source and target column, then we run the assign_vertex_id function ...:

-- Add "source" and "target" column

ALTER TABLE ways ADD COLUMN "source" integer;

ALTER TABLE ways ADD COLUMN "target" integer;

-- Run topology function (eg.)

assign_vertex_id(’<table>’, float tolerance, ’<geometry column’, ’<gid>’)

SELECT assign_vertex_id(’ways’, 0.00001, ’the_geom’, ’gid’);

Public Transit Implementation using pgRouting

• Data in-Use:

▫ POI tables

Bus Stops

Malls and Cinema Halls

Hospitals .. etc

▫ Road Network

▫ Bus Routes

Without Change-Over from Source to

Destination Route Finding

References:

• Setting up pgRouting http://www.gpsfiledepot.com/tutorials/installing-and-setting-uppostgresql-with-postgis/ 1/2

• pgRouting Workshop http://workshop.pgrouting.org/index.html

• pgRouting Documents http://www.pgrouting.org/docs/

• PostGIS in Action

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