sacro / woodpecker

A way to overlay and combine two linear geographic network models

Woodpecker

This is a way to overlay and combine two linear geographic network models.

Overview

The centre-line track-model is a dataset published via an Environmental Information Regulations (EIR) request by Network Rail under the Open Government Licence:

Open Street Map contains current and historic mainland Britain railway data here published under the Open Database License.

Run the following script:

$ ./run.sh

This will downloads dependencies, centre-line and OSM data, creates the network overlay and combines this in a outputx.gpkg repository.

Overlay and combine approach

The approach used to overlay and combine data is:

1. create a cropped OSM and centre-line track-model LineString segments within scaled hexagons
2. create line-extended centre-line track-model rectangular polygons within a given hexagon
3. test if the OSM LineStrings are within these rectangular polygons
4. any OSM LineString segments that fall within a centre-line track-model rectangular polygon are discarded.
5. hexagons are classified as to whether they contain no rail, only OSM, only centre-line or a mixture of elements.
6. OSM data in hexagons only containing OSM elements are retained.
7. hexagons with mixed OSM and centre-line data are reassessed but at the next granular hexagon level.
8. the combined OSM only data and centre-line model then seems to give the required result.