This check identifies Edges which have duplicates. Each Segment in each Edge is checked to identify if the Edge is at all duplicated. The Edge is flagged if any Segment duplicated - this includes partially and completely duplicated Edges.
The following examples illustrate cases where Edges have duplicates.
- This edge id:536929208 should be flagged as a result of it being a partially duplicated Edge.
- This edge id:24628387 should be flagged as a result of it being a partially duplicated Edge.
In Atlas, OSM elements are represented as Edges, Points, Lines, Nodes & Relations; in our case, we’re working with Edges. We’ll use this information to filter our potential flag candidates.
Our first goal is to validate the incoming Atlas Object. We know two things about roundabouts:
- Must be a valid Edge
- Must be a main Edge
- Must be car-navigable
- Must not be part of an area
- Must have not already been flagged
@Override
public boolean validCheckForObject(final AtlasObject object)
{
return object instanceof Edge
// Check to see that the Edge is a main Edge
&& Edge.isMainEdgeIdentifier(object.getIdentifier())
// Check to see that the edge has not already been seen
&& !this.isFlagged(object.getIdentifier())
// Check to see that the edge is car navigable
&& HighwayTag.isCarNavigableHighway(object)
// The edge is not part of an area
&& !object.getTag(AreaTag.KEY).isPresent();
}After the preliminary filtering of features, we take each Edge and use a series of conditional statements to validate whether we do in fact want to flag the feature for inspection.
@Override
protected Optional<CheckFlag> flag(final AtlasObject object)
{
final Edge edge = (Edge) object;
final PolyLine edgePoly = edge.asPolyLine();
final Rectangle bounds = edge.asPolyLine().bounds();
// Get Edges which are contained by or intersect the bounds, and then filter
// Out the non-main Edges as the bounds Edges are not guaranteed to be uni-directional
final Iterable<Edge> edgesInBounds = edge.getAtlas().edgesIntersecting(bounds,
Edge::isMainEdge);
for (final Edge edgeInBounds : edgesInBounds)
{
// If the Edge found in the bounds has an area tag or if the Edge has a length of 0
// Or if the Edge has already been flagged before or if the Edge in bounds is the
// Edge that the bounds was drawn with then continue because we don't want to
// Flag area Edges, duplicate Nodes, already flagged Edges, or the Edge of interest
if (edgeInBounds.getTag(AreaTag.KEY).isPresent()
|| edgeInBounds.asPolyLine().length().equals(ZERO_DISTANCE)
|| this.isFlagged(edgeInBounds.getIdentifier())
|| edge.getIdentifier() == edgeInBounds.getIdentifier())
{
continue;
}
final PolyLine edgeInBoundsPoly = edgeInBounds.asPolyLine();
// Getting the longerEdge and subsetEdge are necessary as .overlapShapeOf() checks that
// the longerEdge is at least the same shape as the subsetEdge. If we were to call this
// method on the subsetEdge with the longerEdge as the parameter, it would return False.
PolyLine longerEdge = (edgePoly.length().isGreaterThan(edgeInBoundsPoly.length())) ?
edgePoly : edgeInBoundsPoly;
PolyLine subsetEdge = (longerEdge == edgePoly) ? edgeInBoundsPoly : edgePoly;
// Checks that either the edgeInBounds PolyLine overlaps the edgePoly or
// That the edgePoly overlaps the edgeInBoundsPoly
if (longerEdge.overlapsShapeOf(subsetEdge))
{
this.markAsFlagged(edgeInBounds.getIdentifier());
return Optional.of(this.createFlag(edgeInBounds,
this.getLocalizedInstruction(0, edgeInBounds.getOsmIdentifier())));
}
}
return Optional.empty();
}To learn more about the code, please look at the comments in the source code for the check. DuplicateWaysCheck.java