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UID:pretalx-qgis-uc2026-8FXBFC@talks.osgeo.org
DTSTART;TZID=CET:20261006T140000
DTEND;TZID=CET:20261006T143000
DESCRIPTION:We used QGIS combined with the capabilities of PostGIS to creat
 e a plugin allowing to visualize and edit topological road network data wi
 th linear referencing capabilities.\n\nThe data is stored in a PostgreSQL 
 database\, and trigger functions are used to:\n* Automatically populate ce
 rtain fields (creation date\, modification date\, length\, etc.)\n* Respec
 t topological rules (segments\, nodes\, connections\, etc.)\n* Automate ce
 rtain tasks: automatically split roads at intersections\, automatically cr
 eate upstream and downstream nodes for segments\, etc.\n\nPostgreSQL funct
 ions are also used for linear referencing calculations: to determine the r
 eference marker ID (“PR”)\, the curvilinear abscissa\, the distance to
  the road (right or left). For example\, “D809 PR 2+135\, side G\, offse
 t 3.4 m” for a point on the map.\n\nIn QGIS\, we have enabled the advanc
 ed editing options in the project properties to facilitate digitizing\, in
 cluding automatic transaction groups that allow users to immediately see h
 ow entering a feature affects other layers (clipping\, moving\, etc.). Thi
 s allows users to see the results of the database calculations right away 
 without having to save their edits.\n\nWe also made full use of QGIS's cap
 abilities for interacting with the database:\n* Advanced search by adding 
 an item to QGIS's global search tool (shortcut “CTRL+K”) that automati
 cally zooms in on a specific location using an address in the format “[r
 oad code] [marker] [abscissa]”\n* Real-time display of references when h
 overing over a road via a toolbar button. When enabled\, a query correspon
 ding to the mouse coordinates is launched\, and the database response is d
 isplayed\n* Python actions for certain layers to initiate processing on an
  object. For example\, a right-click allows you to finalize the creation o
 f a roundabout based on the digitization of a circle at the intersection o
 f road segments.\n\nOf course\, QGIS’s editing forms also ensure that at
 tributes are edited correctly across different tables\, particularly throu
 gh expression constraints and advanced tools that provide drop-down lists\
 , checkboxes\, the ability to select a parent segment by clicking on the m
 ap (the “Relationship Reference” tool)\, and so on.\n\nFor the tool’
 s more complex functions\, we created algorithms for the QGIS Processing t
 oolbox: creating the structure (tables\, functions)\, importing data\, cop
 ying data into an editing sandbox\, and validating that data.\n\nIn this p
 resentation\, we will demonstrate how QGIS addresses a complex business ch
 allenge while serving as a robust interface to a PostgreSQL database.
DTSTAMP:20260724T214531Z
LOCATION:Bridge 2
SUMMARY:Managing a topological county road 🚗 network: linear referencing
  with QGIS & PostGIS - René-Luc Dhont\, Michaël DOUCHIN
URL:https://talks.osgeo.org/qgis-uc2026/talk/8FXBFC/
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