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Calculate measures on a specific point on a line

  • August 3, 2016
  • 6 replies
  • 376 views
T
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Dear FME community,

I have a line and a point dataset. The lines have measures, generated with the MeasureGenerator. Is there a way to extract these measures on a specific point? The points are in the other dataset.

For example: The blue line has the measures (1 per coordinate). The red point is another dataset which intersects the blue line. How can I access the measure at the location of the red point?

I can access the measures at the beginning of the line with the following settings (and save these in the attribute Netz_VST), but how can I tell him to use the point dataset?

Many thanks and best wishes

Thomas

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6 replies

takashi
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  • takashiCelebrity
  • August 3, 2016

Hi @thomask, the PointOnLineOverlayer will give measure to the input point based on the line measure (FME 2015.1+). You can then extract the measure from the output point using the MeasureExtractor (Type: Point).

Why not inspect features with Visual/Data Preview and Feature/Record Information before writing them into a destination dataset?
T
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  • thomask
  • Author
  • August 3, 2016

Unfortunately, he does not show the measures:

The attribute _point_measure is empty:

Here the properties of the MeasureExtractor:

I'm using FME 2015.1.0.3 Build 15485 (32bit).

takashi
Celebrity
  • takashiCelebrity
  • August 3, 2016

Unfortunately, he does not show the measures:

The attribute _point_measure is empty:

Here the properties of the MeasureExtractor:

I'm using FME 2015.1.0.3 Build 15485 (32bit).

generally the PointOnLineOverlayer cannot overlay point on line with 0 tolerance, because there is unavoidable computational error. Try setting very slight amount as the tolerance. e.g. 1e-8 or so.

Why not inspect features with Visual/Data Preview and Feature/Record Information before writing them into a destination dataset?
T
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  • thomask
  • Author
  • August 3, 2016

generally the PointOnLineOverlayer cannot overlay point on line with 0 tolerance, because there is unavoidable computational error. Try setting very slight amount as the tolerance. e.g. 1e-8 or so.

Thank you very much! It works perfectly :)

T
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  • thomask
  • Author
  • August 3, 2016

@takashi: One other question: at some entries (2 of 100) it shows the value -1.#IND for _point_measure. Do you have an idea what the cause could be?

T
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  • thomask
  • Author
  • August 3, 2016

@takashi: One other question: at some entries (2 of 100) it shows the value -1.#IND for _point_measure. Do you have an idea what the cause could be?

I found out that it had something to do with the line geometries. 2 of them weren't valid according to the GeometryValidator. Now it seems to work.

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