Hi Paul,
The boundary crossing should be coming out of the iterator in order.
That's what I've always seen when using testing with the
com.bbn.openmap.layer.test.GeoIntersectionLayer.
Have you rendered the regions and intersection points to see if the
results make sense? You're not working in cartesian space, and you
might see something you didn't expect when the route and regions are
rendered.
- Don
On Sep 11, 2009, at 6:28 AM, Paul Chisholm wrote:
> Hi,
>
> I am using the BoundaryCrossing feature of OpenMap to determine the
> polygons that a path crosses. According to the API the
> BoundaryCrossing.Collector.compact method is "An important method
> that cleans up the segment/region BoundaryCrossing order, and also
> resolves the BoundaryCrossing.in/out settings for regions. Must be
> called before the crossing iterator is retrieved, but the
> BoundaryCrossing method does that." The
> BoundaryCrossing.Collector.getCrossings method calls "compact"
> before generating the iterator. However, I seem to get strange
> results. When I run the following program
>
> import com.bbn.openmap.geo.*;
> import java.util.*;
>
> public class Test {
> public static void main(String[] args) {
> List<GeoRegion> regions = new ArrayList();
> GeoRegion.Impl x = new GeoRegion.Impl(new float[]{10, 10,
> -10, 10, -10, 20, 10, 20, 10, 10});
> x.setID("A");
> regions.add(x);
> GeoRegion.Impl y = new GeoRegion.Impl(new float[]{10, 30,
> -10, 30, -10, 40, 10, 40, 10, 30});
> y.setID("B");
> regions.add(y);
> float[] route = {0, 0, 0, 25, 0, 50}; /
> *****************************/
> GeoPath.Impl path = new GeoPath.Impl(route);
> BoundaryCrossing.Collector bcc = BoundaryCrossing.getCrossings
> (path, regions);
> Iterator it = bcc.getCrossings();
> while (it.hasNext()) {
> BoundaryCrossing o = (BoundaryCrossing) it.next();
> GeoRegion in = o.getIn();
> GeoRegion ou = o.getOut();
> System.out.println(o.getGeo());
> if (in != null) {
> System.out.println(" Enter " + in.getID());
> }
> if (ou != null) {
> System.out.println(" Exit " + ou.getID());
> }
> }
> }
> }
>
> I get the output
>
> Geo[-0.0,29.999999612082494]
> Enter B
> Geo[-0.0,9.999999573437877]
> Enter A
> Geo[-0.0,19.999999678147237]
> Exit A
> Geo[-0.0,40.00000052659251]
> Exit B
>
> The points I understand, but I expected them to appear in order
> Enter A, Exit A, Enter B, Exit B
>
> When I replace the line labelled
>
> /*****************/
>
> with
>
> float[] route = {0, 50, 0, 25, 0, 0};
>
> i.e. reverse the direction of the path, the output is
>
> Geo[0.0,19.999999678147237]
> Enter A
> Geo[0.0,9.999999573437877]
> Exit A
> Geo[0.0,40.00000052659251]
> Enter B
> Geo[0.0,29.999999612082494]
> Exit B
>
> Is my understanding of the order in which the iterator returns
> crossing points incorrect? If so, is there any way to order the
> crossings in the sequence they are visited along the direction of
> the path.
>
> Thanks,
> Paul
>
> --
> [To unsubscribe to this list send an email to "majdart_at_bbn.com"
> with the following text in the BODY of the message "unsubscribe
> openmap-users"]
--
[To unsubscribe to this list send an email to "majdart_at_bbn.com"
with the following text in the BODY of the message "unsubscribe openmap-users"]
Received on Fri Sep 11 2009 - 11:54:41 EDT