The Issues in Understanding OSRM Graph Representation

[freshFishhh]

I need some help guys. I cant understand that the 'Basic Changes of Convert OSM to OSRM Edge-expanded Graph' in 'Understanding OSRM Graph Representation'. In my opinion, the segment with particular is a node in OSRM graph,but the last figure in 'Basic Changes of Convert OSM to OSRM Edge-expanded Graph' is not clear. Blue points represent the OSM point, and a segment between to OSM points equals a edge in graph, why the red line(a segement) include two black points? And I think its contradicting.

[freshFishhh]

please!!!

[wangyoucao577]

Have a look at Process of Convert OSM to OSRM Edge-expanded Graph. The OSRM Edge-expanded graph generally means abstract OSM Way to Graph Node. Each OSM Way has two directions, so each direction is a Graph Node. Go back to your question, actually each black point is a directed OSM way.

[freshFishhh]

I have understood this issue by your kind help. I am learning how the data converting to OSRM graph by extractor and contractor (especially the code of car.lua), which is so complex for me. Thanks for you help, and I may bother you again.