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How to find unnecessary network (line)

  • April 25, 2023
  • 8 replies
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Z
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Dear Sir / Madam,

 

I have an indoor data set. As shown in the figure below.

 

Red line represents network path.

Blue circle is the POI (Point).

Black dot is just the vertex.

 

As I have an indoor data for the entire building. I would like to find network that is unnecessary (not linked with any POI), as shown as Yellow Circle.

 

I am just wondering what transformers I can use to find these path?

I cannot just simply break the lines as some vertex are necessary for turning.

 

I would really need some hand.

 

Thank you very much!

Best answer by geomancer

Look into the ShortestpathFinder. This transformer uses the network (which you already have) and From-To lines connecting every pair of POI.

There are many ways to create those From-To lines. An easy way is to create lines between all POI, and keep only the lines going from a POI_ID to a higher POI_ID.

The segments that you are interested in exit the ShortestpathFinder from the Unused port.

ShortestPathFinder

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    8 replies

    geomancer
    Evangelist
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    • geomancerEvangelist
    • Evangelist
    • 932 replies
    • Best Answer
    • April 25, 2023

    Look into the ShortestpathFinder. This transformer uses the network (which you already have) and From-To lines connecting every pair of POI.

    There are many ways to create those From-To lines. An easy way is to create lines between all POI, and keep only the lines going from a POI_ID to a higher POI_ID.

    The segments that you are interested in exit the ShortestpathFinder from the Unused port.

    ShortestPathFinder

    david_r
    Celebrity
    • david_rCelebrity
    • 8391 replies
    • April 25, 2023

    The NetworkTopologyCalculator might be a starting point.

    Z
    Forum|alt.badge.img

    Look into the ShortestpathFinder. This transformer uses the network (which you already have) and From-To lines connecting every pair of POI.

    There are many ways to create those From-To lines. An easy way is to create lines between all POI, and keep only the lines going from a POI_ID to a higher POI_ID.

    The segments that you are interested in exit the ShortestpathFinder from the Unused port.

    ShortestPathFinder

    @geomancer​ Thank you soooooooooooo much for your detailed workspace, it helps a lot!!! As I have no clue where to start.

    However, I tried to modify a little bit, since I have to do this on each floor. At the end, the shortestpathfinder transformer couldn't find the path for 2nd floor POI D to E and POI E to F and go to "NoPath". Might I ask what's wrong with my transformer? I have attached my new data and fmw below. I hope you can have some spare time to solve my problem.

     

    Also, I have other questions, what is the purpose for TestFilter. (@Value POI_from < @Value POI)?

     

    Sorry I have asked so many questions.

     

    Again, I am really appreciated your help!

    geomancer
    Evangelist
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    • geomancerEvangelist
    • Evangelist
    • 932 replies
    • April 26, 2023

    Look into the ShortestpathFinder. This transformer uses the network (which you already have) and From-To lines connecting every pair of POI.

    There are many ways to create those From-To lines. An easy way is to create lines between all POI, and keep only the lines going from a POI_ID to a higher POI_ID.

    The segments that you are interested in exit the ShortestpathFinder from the Unused port.

    ShortestPathFinder

    Hi @zacharylee_1204​ , I am glad I can help you! Your lines on floor 2 are not split at the junctions.

    Problematic_LineYou can remedy this with a Chopper in mode 'By Vertex', setting the maximum number of vertices to 2.

     

    TestFilter. (@Value POI_from < @Value POI) reduces the number of lines between the POI. The workflow creates line A-B and line B-A, but you only need one of these lines. The workflow also creates 'line' A-A, which is also not needed.

    Z
    Forum|alt.badge.img

    Hi @zacharylee_1204​ , I am glad I can help you! Your lines on floor 2 are not split at the junctions.

    Problematic_LineYou can remedy this with a Chopper in mode 'By Vertex', setting the maximum number of vertices to 2.

     

    TestFilter. (@Value POI_from < @Value POI) reduces the number of lines between the POI. The workflow creates line A-B and line B-A, but you only need one of these lines. The workflow also creates 'line' A-A, which is also not needed.

    It works!!!!!!!!!!! thank you so much @geomancer​ .

     

    Actually I have already break the lines by using "Intersector", but I am not sure why it doesn't work.

     

    So (@Value POI_from < @Value POI) means it comparing the value? As you said, if it has line A-B and B-A, so B-A is larger than A-B?

    I am kind of confused. Sorry about that ^^"

     

    Anyhow, I am really appreciated your help. It works! YEAH!!!!!!!!!!!!!!!

     

    geomancer
    Evangelist
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    • geomancerEvangelist
    • Evangelist
    • 932 replies
    • April 26, 2023

    Hi @zacharylee_1204​ , I am glad I can help you! Your lines on floor 2 are not split at the junctions. 

    Problematic_LineYou can remedy this with a Chopper in mode 'By Vertex', setting the maximum number of vertices to 2.

     

    TestFilter. (@Value POI_from < @Value POI) reduces the number of lines between the POI. The workflow creates line A-B and line B-A, but you only need one of these lines. The workflow also creates 'line' A-A, which is also not needed.

    Good to know this works 😀 

    The TestFilter compares the value of attribute 'POI_From' with the value of attribute 'POI'. Only when the value of 'POI_from' is smaller than the value of 'POI', the feature passes the test.

    POI_From | POI |  result
        A    |  A  |  fails
        A    |  B  |  passes    --->
        A    |  C  |  passes    --->
        B    |  A  |  fails
        B    |  B  |  fails
        B    |  C  |  passes    --->
        C    |  A  |  fails
        C    |  B  |  fails
        C    |  C  |  fails

     

    Z
    Forum|alt.badge.img

    Hi @zacharylee_1204​ , I am glad I can help you! Your lines on floor 2 are not split at the junctions.

    Problematic_LineYou can remedy this with a Chopper in mode 'By Vertex', setting the maximum number of vertices to 2.

     

    TestFilter. (@Value POI_from < @Value POI) reduces the number of lines between the POI. The workflow creates line A-B and line B-A, but you only need one of these lines. The workflow also creates 'line' A-A, which is also not needed.

    Got it! Thank you so much! You are awesome! :)

    geomancer
    Evangelist
    Forum|alt.badge.img+58
    • geomancerEvangelist
    • Evangelist
    • 932 replies
    • May 8, 2023

    Hi @zacharylee_1204​ , I am glad I can help you! Your lines on floor 2 are not split at the junctions.

    Problematic_LineYou can remedy this with a Chopper in mode 'By Vertex', setting the maximum number of vertices to 2.

     

    TestFilter. (@Value POI_from < @Value POI) reduces the number of lines between the POI. The workflow creates line A-B and line B-A, but you only need one of these lines. The workflow also creates 'line' A-A, which is also not needed.

    This can also be done using a NeighborFinder in Candidates Only mode, instead of the FeatureMerger (see this post for an example).

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