Hi,
In case of polylines (i.e. road segments, single layer) - each polyline
is vertex and edge is pure virtual (so it identifier is -1).
There are different cases, for example:
1. Water network with pipes (vertices) and edges (valves)
2. Road network - each road segment is vertex, edges are virtual
3. Product supply chain - warehouses, shops are vertices, edges may be
virtual or real roads.
Best regards,
Dmitry
19.08.2020 14:38, marto salata пишет:
Thank you very much for your fast reply.
regarding step 2, i have a polyline shapefile, how to get the vertices
required in step 3 so i can connect them.
i know the gfid in the imported shapefile, but from where i can get
the vertices?
On Wed, Aug 19, 2020 at 11:25 AM Dmitry Baryshnikov
<[email protected] <mailto:[email protected]>> wrote:
Hi,
You need to follow these steps:
1. Create empty network
> gnmmanage.exe create -f GNMFile -t_srs "EPSG:4326" -dsco
"net_name=my_network_1" C:\tmp\gnmnetwork
2. Load your data
> gnmmanage.exe import lines.shp -l lines C:\tmp\gnmnetwork
Repeat for all your layers
3. Connect features to create network. Features identifiers set
while importing your spatial data. Use ogrinfo to check them.
> gnmmanage.exe connect 1 2 -1 C:\tmp\gnmnetwork
4. Perform shortest path using Dijkstra
> gnmanalyse.exe dijkstra 1 2 -ds shortestpath.shp -f "ESRI
Shapefile" -l shortestpath C:\tmp\gnmnetwork
Some links:
* https://trac.osgeo.org/gdal/wiki/geography_network_support
* https://nextgis.com/blog/gnm/ <https://nextgis.com/blog/gnm/>
* http://gsoc2014gnm.blogspot.com/
Best regards,
Dmitry
19.08.2020 07:31, marto salata пишет:
dear GDAL team,
how i can create a network using gnmmanage.exe from a polyline
shapefile, so i can perform a dijkstra with gnmanalyse.exe
best regards
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