On 3/10/2015 5:31 AM, Fernando Pacheco wrote:
I understand the idea.
I had imagined something similar but with existing spatial information
and using OSRM directly.
The definition of that stretch of the road goes from node i (OSM-Ni) to
node j (OSM-Nj). The street is two-way. "A" is an intermediate point of
my route (client). "a" is the nearest point of A on the street. The
vehicles driven on the right side of the street.
A
OSM-Ni + --------------- a --------------- + OSM-Nj
If A is the left side of the street: 1 - find the point nearest the
street (a); 2 - add the node OSM-Nj (before node "a") to the route.
OSM-Ni + --------------- a --------------- + OSM-Nj
A
If A is the right side of the street: 1 - find the point nearest the
street (a); 2 - add the node OSM-Ni (before node "a") to the route.
[The first point of the route should be approached in a similar way but
the subsequent node is added after "a" (in flow direction).]
Is this a possible approach to solve the problem with OSRM ?. Thank you
very much. Fernando.
I see two problems with this approach:
1) you have to check the "from" location because if it is already on
edge i-j then you have to adjust your calculations to deal with that.
Say you vehicle location is currently midway between "a" and OSM-Nj and
you want to get to "a" then you would not want route
"from"->"OSM-Nj"->"a" instead you would just want "from"->"a"
A
OSM-Ni + --------------- a -------from-------- + OSM-Nj
This would also need to be done in the example I posted below.
2) OSRM does not provide access to the edge geometries (except to return
the final route geometry) through the API so it would require keeping a
copy of the geometries elsewhere like PostGIS or digging into the OSRM
source code and see if it is possible to add code to find the geometry
and do the calculations.
@Dennis, Any thoughts on how easy/hard this might be to do in the C++
code? and where would one start looking?
Thanks,
-Steve
El 09/03/15 a las 16:34, Stephen Woodbridge escribió:
On 3/9/2015 1:54 PM, Fernando Pacheco wrote:
Hi all.
We are developing an application for routing solid waste collection
trucks. We use OSRM to calculate distances between collecting points
(intermediate points).
Some customers are located in two-way streets (simple, no separators)
... How can I say to OSRM that must arrive to the collecting points at
the adequate side of the street? That is, on the side where the client
is, without crossing the opposite direction of the street to access the
load.
Is it possible?. Thanks in advance. Fernando.
Hi Fernando,
When the street is represented as a single street center line, a via
point is just located on the street segment and then the route is
computed to that point. I do not believe there is any way to say arrive
at this node from a given direction.
One idea for a work around to this problem is to take advantage of the
fact that OSRM does not make u-turns at via points so it might be
possible if you know the location is on the right side of a street (in
right side drive countries) and you can access the geometry to generate
an additional via point before or after the collecting point and then
include both points in order in the route.
so for a simple street:
B A
-----------------------------------
C D
with 4 collection points and you want to collect A and B only when
traversing the street from right to left and C and D only when
traversing the street from left to right. So if we add the lower case
points a,b,c,d as:
B b A a
-----------------------------------
c C d D
Then we can compute a route from say Z (not shown) to A we would compute
the route Z-a-A and this should force OSRM to arrive at A after point a
and this would put it in the correct direction.
Say you want to route A to C then presumably you should be able to route
a-A-c-C, this makes some presumptions that would need to be validated
but the idea is that a-A forces the direction along the street for the
start of the route, then it would have to exit the left end of the
street and either make a u-turn or drive around a block and re-enter the
street from the left to get to c then to C moving in the correct direction.
But as you can see this greatly complicates the problem by potentially
doubling the number of nodes and requiring a lot of pre-computation to
assess the side and direction.
-Steve W
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