Bridge elevation corrections (slopeOverrides)

[MikeN]

I tried to use the new feature to correct slopes so that a bridge over a ravine would be recognized.  I used the following:

Inside

    <bean id="osmBuilder" class="org.opentripplanner.graph_builder.impl.osm.OpenStreetMapGraphBuilderImpl">

I have this

        <property name="defaultWayPropertySetSource">
            <bean class="org.opentripplanner.graph_builder.impl.osm.DefaultWayPropertySetSource" />
        </property>

        <property name="wayPropertySet">
            <bean class="org.opentripplanner.graph_builder.impl.osm.WayPropertySet">
                <property name="slopeOverrides">
                    <list>
                        <bean class="org.opentripplanner.graph_builder.impl.osm.SlopeOverridePicker">
                           <property name="specifier" value="bridge=yes" />
                           <property name="override" value="true" />
                         </bean>
                    </list>
                </property>
            </bean>
        </property>

When I route over a bridge, it still shows the elevation profile dipping down into the ravine.   This is from the OTP source dated 11-August.  How can I track this down?

Thanks,

[David Turner]

Are you having problems at the approaches to the bridge which aren't
tagged bridge=yes? Or the whole thing? Can you show me the OSM way?

[MikeN]

If I understand it, the bridge way elevation slope override algorithm should have been modified to draw a straight line between the endpoints (the ends of this bridge are at slightly different elevations).

It is way 45091886  http://www.openstreetmap.org/browse/way/45091886

I could not find any messages "Unexpectedly missing elevation for edge TurnEdge" for this way or the adjoining ways during the graph build.  It's as though I didn't have the right syntax to make the slopeOverrides active.

   I have attached the elevation profile produced by the walk -

[David Turner]

On Thu, 2012-08-16 at 05:38 -0700, MikeN wrote:
> If I understand it, the bridge way elevation slope override algorithm
> should have been modified to draw a straight line between the
> endpoints (the ends of this bridge are at slightly different
> elevations).

> It is way 45091886 http://www.openstreetmap.org/browse/way/45091886
>
> I could not find any messages "Unexpectedly missing elevation for edge
> TurnEdge" for this way or the adjoining ways during the graph build.
> It's as though I didn't have the right syntax to make the
> slopeOverrides active.
>
> I have attached the elevation profile produced by the walk -

OK, I finally got a chance to look into this. It is indeed drawing a
straight line between the endpoints. Unfortunately, the left endpoint
is at a much lower elevation than the right. Basically, the underlying
ground dips slightly before the bridge starts. Weirdly, it also seems to
be lower after the bridge ends, if the Bing satellite photos are to be
believed, but maybe the NED sample for that location is taken on the
higher ground. I just adjusted the OSM so that the bridge starts a bit
earlier, which seems to fix the problem.

[MikeN]

Many thanks for looking at this - I can now use this technique to fix the other areas!  I'll remember to give bridges a generous overlap when possible, to prevent this type of issue in other areas.