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count number of points in a solid

  • November 29, 2018
  • 4 replies
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D
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Hi FME community

 

 

I try to count the number of points (from *.las point cloud) in a solid. The solid comes from an extruded polygon.

 

 

The goal of it is to figure out if the point cloud matches an existing 2D CAD Plan. To do this I take the polyline of the walls and extrude them. Afterwards I would like to count the number of point inside the extruded solid (wall). If this results in many points I can assume that the wall is correct - if not the wall must be incorrect.

 

 

It would be great if someone has any idea and can help me. I only struggle with the count of the points in the solid.

 

 

Thanks in advance and kind regards form Switzerland

 

Dominik

Best answer by dominik

Hi takashi

 

 

Thanks for your effort and answer. In the meantime I figure out a similar way:

 

1. I use the 2DForcer for the point cloud (so every point is on z=0)

 

2. I use an PointOnAreaOverlayer to count the number of points inside the wall

 

 

This works perfect for me!

 

 

Thanks anyway!

 

Dominik
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4 replies

takashi
Influencer
  • takashiInfluencer
  • November 29, 2018

Hi, if the solid is a simple one which is created by extruding a flat polygon towards z-axis direction, a possible way is:

  1. BoundsExtractor: Extarct zmin and zmax of the extrusion solid.
  2. SurfaceFootprintReplacer: Replace the solid with a 2D polygon.
  3. Clipper (Check the Merge Attributes option): Clip the point cloud by the polygon.
  4. PointCloudFilter: Create a point cloud consisting of points whose z-coordinate are within the zmin and zmax.
  5. PointCloudPropertyExtractor: Count the number of the resulting point cloud.
gio
Contributor
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  • gioContributor
  • Contributor
  • November 29, 2018

@dominik

You can use a clipper for that

Use your solid as clipper.

 

D
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  • dominik
  • Author
  • Best Answer
  • November 29, 2018

Hi takashi

 

 

Thanks for your effort and answer. In the meantime I figure out a similar way:

 

1. I use the 2DForcer for the point cloud (so every point is on z=0)

 

2. I use an PointOnAreaOverlayer to count the number of points inside the wall

 

 

This works perfect for me!

 

 

Thanks anyway!

 

Dominik
takashi
Influencer
  • takashiInfluencer
  • November 29, 2018
gio wrote:

@dominik

You can use a clipper for that

Use your solid as clipper.

 

I didn't know the Clipper supports 3D clipping on point cloud. Good to hear :-) Thanks.

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