Network City I // Distances in a Graph – Representation problems

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This topic contains 5 replies, has 2 voices, and was last updated by  Reinhard Koenig 1 month, 2 weeks ago.

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  • #9603

    Kevin Carvalho
    Participant

    Hello, mr. Reinhard

    First of all, congratulations for the work in DecodingSpaces, again.

    Well, I’ve applied successfully the network calculation with the Betweeness Centrality Weighted results, and I exported the results to shapefile (via BearGIS, a nice plugin for shp exporting). Now, comparing the shapefile view in ArcMap (from ArcGIS) to the visualization in Rhino, I see a giant difference. In GIS, I see the line with the right colours, according to its values, while in Rhino I can’t get the same result.

    See the images. In grasshopper (right image), gradient receives the “values” from 0 to 1, so it should show blue streets in lower values and red in the bigger values. It doesn’t happen in GH, that doesn’t show blue lines at all, while in ArcGIS (left image) it happens in the right way.

    What is happening in Rhino that doesn’t show the same result?

    The gh file is attached.

    Thank you in advance,
    Kevin

  • #9604

    Kevin Carvalho
    Participant

    The attachment didn’t work, i’ll try again here, with the ZIP. Also, I add the attribute table’s printscreen from ArcGIS, so you can see the index numbers and how it matches with Rhino. 

    Attachments:
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  • #9606

    Kevin Carvalho
    Participant

    Well, sorry for the long post.

    But I saw the problem. Rhino gives value 0.00 to the blue and 0.50 to the yellow and 1.00 to the red, while ArcGIS doesn’t give colours to numbers that doesn’t exist. For example, there is no 0.20 value: 0.20 would be blue in GH while 0.40 would be yellow. ArcGIS jumps the values that does not exist, so 0.40 is still blue. So, how can I make GH give colours the same way GIS does?

  • #9607

    Reinhard Koenig
    Keymaster

    Dear Kevin,

    you need to adjust the upper or lower bound value for the color gradient – add a value to it and you’ll see also blue lines in Grasshopper.

    Concerning your last post, you can filter the invalid or 0 values.

    Best regards

    Reinhard

  • #9619

    Kevin Carvalho
    Participant

    Thank you for the answer, mr. Koenig.

    Also, I’m analysing another result. When the street network has avenues with double lines (one for each way), as you can see in the image bellow, I wonder what means the result: if it’s a medium centrality (yellow), if it was only one segment, probably it would be red? I’m wondering how the script deals with those kind of representation, double lines for only one avenue. I’ll do the test without that kind of street, but I would like to know what you think.

    Avenues that has two segments, one for each way

    Best regards,

    Kevin

    • #9621

      Reinhard Koenig
      Keymaster

      Dear Kevin,

      The issue with parallel lines for the “same” street is a problem for all kinds of network analysis. The only way to deal with it is to clean the data before the analysis (=merge the two street center lines). Also, the roundabouts in your map could distort your analysis if they consist of many small line segments (=many origins and destinations). There are tools for simplifying street networks (in QGIS, ArcGIS, and not that advanced in the DeCodingSpaces-Toolbox), or you do it manually.

      Best regards

      Reinhard

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