This presentation will show the inside and current state of pgRouting development. It will explain the shortest path search in real road networks and how the data structure is important for getting better routing results. We will show how you can improve the quality of the search with dynamic costs and make the result look closer to the reality. We will demonstrate the way of using pgRouting together with other Open Source tools. Also you will learn about difficulties and limitations of implementing routing functionality in GIS applications, the difference between algorithms and their performance. pgRouting is an extension of PostgreSQL and PostGIS. A predecessor of pgRouting - pgDijkstra, written by Sylvain Pasche from Camptocamp, was extended by Orkney (Japan) and renamed to pgRouting, which now is a part of the PostLBS project. pgRouting can perform: * shortest path search (with 3 different algorithms) * Traveling Salesperson Problem solution (TSP) * driving distance geometry calculation

1. Shortest path search for
real road networks
Anton Patrushev

2. What is pgRouting?

3. Shortest path

4. TSP and DD

5. VRP (DARP)

6. Real road networks
How do they look like?

7. Like this...

8. ...or like this...

9. ...or sometimes like this.

10. What makes them real?
traffic lights signs road marking

11. How pgRouting can help here?

12. gid,
source,
source target,
cost,
reverse_cost,
x1, y1,
x2, y2,
rule,
to_cost
target

13. Traffic lights make you slower.
It means we should increase costs.

14. B
C
1min
A
D
cost(A)=cost(A)+30sec
cost(B)=cost(B)+30sec
cost(C)=cost(C)+30sec
cost(D)=cost(D)+30sec

15. Signs tell you about
restrictions and road types.

17. cost(A)=length(A)
reverse_cost(A)=∞
A

18. Sometimes the
costs have
different
meaning.

19. cost(A)=length(A)/2
reverse_cost(A)=length(A)*2
cost(B)=length(B)*3
reverse_cost(B)=length(B)/3
B
A

20. Turn restrictions
obviously restrict
turns.

21. B
C
1min
A
D
cost(A)=cost(A)+1min
cost(B)=cost(B)+1min
rule(A)="D"
cost(C)=cost(C)+1min
to_cost(A, D)=∞
cost(D)=cost(D)+1min

22. Road type signs
can be used for
cost calculation.

23. Not only types, but
also conditions.

24. What about road
marking?

25. It separates
lanes, ...

26. ...specifies road
types, ...

27. ... and restrictions.
C
A D
B
E
rule(D)="A, B"
to_cost(D)=∞

28. And you know what's cool about
pgRouting?

29. All costs are dynamic.
Which is opposite to pre-calculated.

30. If the road is closed, ...

31. ... there is an accident, ...

32. ... a sign with
restrictions limited
in time, ...

33.
... bad weather conditions, ...

34. ... or an obstacle, ...

35. You don't need to
rebuild and reload
your network...

36. ... and wait forever.

37. You only need to adjust the cost for
this particular road.
And next search will go another way.

38. Cost can be virtually
anything.

39. It is possible to use pgRouting
with OSM data.

40. pgRouting can be used for different
kinds of networks.

41. Canals and
rivers, ...

42. ... hiking trails, ...

43. ... or any other
kind of network.

44. Now it's showtime!

45. Thanks to sxc.hu for being the best free
photo stock.
Thanks to people who put their photos to
flickr under Creative Commons license.

46. Just want you to remember
pgrouting.org
georepublic.de
openvrp.com