Hi Trevor,
All of your questions are valid ones. The explanation is that the
author decided to do the route calculations in x/y space, making the
fidelity of the information completely dependent on the projection
view (area covered and scale).
This package needs to be updated to do these calculations in lat/lon
space, but those modifications won't be implemented for OM5. The
layers that use the code were used for a demo/proof-of-concept a while
back, and we didn't have a chance to update it.
I was going to suggest looking into modifying the code to use a
projection you define, one that covers all of your roads with a small
scale value for good fidelity, but as I look at the code that'll
introduce some problems with the display, especially if the projection
changes. It's almost as much work as just making the modifications so
the code just works in lat/lon space.
I wish I had a better suggestion.
- Don
On Mon, Aug 16, 2010 at 3:55 PM, Gerhardt, Trevor R
<tgerhardt_at_alionscience.com> wrote:
> I am currently using OpenMap 4.6.5 to load in a shape file containing road
> data retrieved from esri.com and need to find the best route from one
> lat/lon point to another. I have a MultiRoadLayer that appears to accurately
> draw the roads loaded in and have retrieved a Route from the RoadFinder.
>
>
>
> My first problem is that, depending on the scale of the map and the zoom
> level, I retrieve different and seemingly inaccurate data from the
> getPathOnRoad method. My second problem is that if you ask for a best route
> that is not currently viewable in the bounds of the projection it will not
> actually get the best route because the data it asks for is not retrieved
> and stored when the projection is changed. The solution is probably related.
>
>
>
> Am I just completely overlooking something that is an easy and simple
> solution?
>
>
>
> Why would the lat/lons given by the intersection and road data be different
> depending on the zoom level? Shouldn’t the intersection and road data be
> exactly the same internally and only the displayed points be converted?
> Could it be a fidelity issue and if so is there a way to turn up the
> fidelity? Is there a separate list maintained that contains or will retrieve
> the same road data each time that was directly loaded from the shape file
> that does not get modified when converting to the displayed shapes? Were the
> Roadfinder and MultiRoadLayer classes only set up as templates and guides
> for what you can implement yourself and not actually supposed to be used out
> of the box?
>
>
>
> Are there any significant changes to the roads in 5.0 that could give me
> options or tools to solve this?
>
>
>
> Please let me know if you need any more information.
>
>
>
> Thanks,
>
>
>
> Trevor
>
>
>
> Trevor Richard Gerhardt
>
> Software Design Engineer
>
> Alion Science & Technology
>
> (757) 857-5670 x372
>
> tgerhardt_at_alionscience.com
>
>
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Received on Wed Aug 18 2010 - 16:15:40 EDT