Question

Create bottom edges of the solid geometry classes

  • 11 March 2022
  • 2 replies
  • 4 views

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Hi FME:ers!

My task is to find a way to create polygons at the bottom of each solid geometry classes. The created polygons should follow the solid geometry classes bottom edges (x, y and z). I have marked a dark line in the picture for more understanding.

 

image 


2 replies

Userlevel 2
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Hi @quangu​ , I found that each object is an aggregate of a lot of voxel boundaries.

If I understand your requirement and data structure correctly, the workflow shown in the screenshot extracts "bottom" surfaces for each class.

Deaggregtor: Decompose the objects into individual voxel surfaces.

Matcher: Filter out internal surfaces, which are duplicated.

PlanarityFilter: Calculate the normal vector for each surface.

Tester: Select "bottom" surfaces, whose z-component of normal vector is equal to -1 (i.e. downward).extract-bottom-surfaces

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Thank you so much takashi, this is what im looking for!

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