topic Determining Upstream and Downstream polylines in ArcObjects SDK Questions

Determining Upstream and Downstream polylines

KevinYanuk — Tue, 14 May 2013 14:53:52 GMT

Hello,

I am looking for the best approach to determining the upstream and downstream polylines of two segments.

I have code that has just split a polyline into two segments:

ISet newSet = featureEditor.Split(_pointFeature);
IFeature newLine = (IFeature)newSet.Next();
while (newLine != null)
{
     // determine up / downstream?  or old / new sewer?
     newLine = (IFeature)newSet.Next();
}

Thanks!

Re: Determining Upstream and Downstream polylines

TerryGiles — Thu, 23 May 2013 00:55:26 GMT

It's been a while but my recollection from dealing with street centerlines is that both resulting geometries would follow the direction of the origin polyline. A polyline has a FromPoint and ToPoint which gives you an idea of the direction it is going. If you need to know which is upstream for the other, check the new segments ToPoint & FromPoint... if lineA.FromPoint = LineB.ToPoint then Line B is 'upstream' (according to the original feature's direction).