Wrapping Edges Around Anti-meridian

Hi,

I am working on a waterways project. I prepared the data with two caveats that I found on various channels to wrap the edges around anti-meridian with the basic objective that the points at -180 and +180 longitudes merge.

  1. Ensured that edges terminate at +180 and -180 longitudes and do not cross the boundary but they end at exactly same latitudes where they are intended to cross and connect.
  2. Provided tag of ‘closure_segment = yes’ by drawing a boundary on either end that connected with the points terminating at ±180 degree longitudes

When we ran the tests, we found that Graphhopper wouldn’t merge the points and wrap the earth around ±180 degree longitude.

Request your guidance on data preparation around ±180 degrees for it to work.

Regards,

Yes, currently the situation at ±180 is not supported No antemeridian support? · Issue #2745 · graphhopper/graphhopper · GitHub

1 Like

Hi,

Thanks for a quick response. As mentioned in the #2745 , the easiest way to do it would be to assign the same id to the nodes at ±180 degrees. It is doable on sql but looks like a big challenge when it comes to OSM/Graphhopper. Let us say if I want to assign the same location index or id to those nodes/edges on the graph, how should I go about it?

Sorry, I do not know what the exact problem (or solution) is and it currently has low priority IMO.

Sure. Thanks again. On a different note - Let us say if I create jumper edges with z level = 100 and connect the ±180 degree points, what would be the geographical distance of these jumper edges calculated by Graphhopper? Geographical distance should be zero for same latitudes.

Regards,

It should calculated zero, yes, but I have not tried it. But you can easily try it out.

I can confirm that the prepared graph calculates the length as zero and considers only one node for such edges. Graphhopper frontend however is not able to recognise points on ±180 to provide routes. May be it needs some modification.

Have seen a post of yours, where you talk about making three lines when crossing anti-meridian. Cannot find it online again. Anything that you can recall.