Is your directional linear network driving you crazy? These 3 interdependent models will help you find and fix a multitude of problems in your GIS network so that your network analysis (like shortest path) will work flawlessly without the need to use a topology tolerance to compensate for bad data. Basically, it will help you create a perfect line network! It makes a great complement to the topology checker plugin.

Model 3 aims to fix the network and will:

-a) Snap and split lines that are disconnected if they are within a user specified distance (see 2.d above). Only the first or last nodes (vertices) of a line are moved.

-b) Show to the user what lines have been modified

-c) Check the output geometries for errors in case the algorithm has created invalid geometries (ex: zero length lines, duplicate nodes…) (New in version 2). An empty output layer means there are no errors found.

The fixed output network should then be re-run in model 2 to see what errors remain.

All models provide a way to track changes when modifications are done to the network file. The only exception to this rule is the deleted duplicate geometries and duplicate nodes of model 1. The original Feature ID is maintained to help the user merge old databases with the new geometries. The original input data is read but never modified.

Visit the project web site at https://gitlab.com/njacadieux/fix-directional-network-qgis-models and read “A Python Algorithm for Shortest-Path River Network Distance Calculations Considering River Flow Direction” for more details https://doi.org/10.3390/data5010008.

Watch my presentation of the model at the QGIS Open Day (2023-02-24) https://www.youtube.com/live/xmxPeAXLTx0?feature=share

Please go to https://plugins.qgis.org/models/ or to https://gitlab.com/njacadieux/fix-directional-network-qgis-models/ to download the models, test data or to file bug reports.

Built and tested on QGIS 3.28.2, seems to work with QGIS 3.22.10 LTR