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unexpected result of the network flow orientor

  • July 11, 2017
  • 2 replies
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femo
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Hi,

I am using the networl flow orientor to check the direction of digitisation agains a given flow direction.

This is a snippet of the script, i have also attached it, together with the 3 lines and the one destination point (fme 2017):

I expected all three lines to have the same _direction value "same". However, the one with GISID 3128

shows up with the value "opposite". But if one Looks at the coordinate order they all goes towards the destination point. I do not understand the behaviour!

Best answer by takashi

"opposite" here means that the direction of the original line WAS opposite against the flow direction. The NetworkFlowOrientor reverses the "opposite" lines, so all the resulting lines orient the same direction as flow.

"Fixes the flow (direction) of each edge or linear feature in the network to fit the downstream direction to the destination node. ... Parameters | Direction Attribute: If an edge is reversed, the value of the attribute specified in Direction Attribute will be opposite. Otherwise, the value will be same." -- NetworkFlowOrientor Help
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2 replies

takashi
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  • takashiCelebrity
  • Best Answer
  • July 11, 2017

"opposite" here means that the direction of the original line WAS opposite against the flow direction. The NetworkFlowOrientor reverses the "opposite" lines, so all the resulting lines orient the same direction as flow.

"Fixes the flow (direction) of each edge or linear feature in the network to fit the downstream direction to the destination node. ... Parameters | Direction Attribute: If an edge is reversed, the value of the attribute specified in Direction Attribute will be opposite. Otherwise, the value will be same." -- NetworkFlowOrientor Help
Why not inspect features with Visual/Data Preview and Feature/Record Information before writing them into a destination dataset?
femo
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  • femoContributor
  • Author
  • Contributor
  • July 12, 2017

"opposite" here means that the direction of the original line WAS opposite against the flow direction. The NetworkFlowOrientor reverses the "opposite" lines, so all the resulting lines orient the same direction as flow.

"Fixes the flow (direction) of each edge or linear feature in the network to fit the downstream direction to the destination node. ... Parameters | Direction Attribute: If an edge is reversed, the value of the attribute specified in Direction Attribute will be opposite. Otherwise, the value will be same." -- NetworkFlowOrientor Help
I should better read the documentation! Behaviour is exactly as described.

 

 

 

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