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3d intersection

  • October 8, 2014
  • 1 reply
  • 48 views
D
Hello,

 

 

I needto check visibilities between a set of 3d-points. Therefore I created 3d-lines from pairwise 3d-points and tried to check for 3d intersections between the generated 3d-lines and 3d-surfaces/a DEM (WallSurfaces of a CityGML model). I used the SpatialRelator and SpatialFilter, but it seems, as if those transformers just work in two dimensions, because there were intersections detected, altough there is none in 3d?!

 

All I need is the information, if the input-lines intersect one or more surface(s) or the DEM and not which part of the DEM/which surface is intersected.

 

 

Thanks

Best answer by gio

Yeah, thase give you "apparent intersection" in 3D.

 

 

If you have like "high School Math" and a lot of stamina u could go for matrixcalcuation.

 

 

U you can use the 3DAffiner.

 

 

I made 2D affiner for inetersections...and when u convert it to fme attribute syntax..it becomes almost unreadable..but works like a charm.

 

2D lineintersect..

 

 

 

AttributeCreator [AttributeCreator]

 

Ix = @Evaluate(((@Value(Sx)*@Value(Ey)-@Value(Sy)*@Value(Ex))*(@Value(Sx_t)-@Value(Ex_t))-(@Value(Sx)-@Value(Ex))*(@Value(Sx_t)*@Value(Ey_t)-@Value(Sy_t)*@Value(Ex_t)))/((@Value(Sx)-@Value(Ex))*(@Value(Sy_t)-@Value(Ey_t))-(@Value(Sy)-@Value(Ey))*(@Value(Sx_t)-@Value(Ex_t))))

 

Iy = @Evaluate(((@Value(Sx)*@Value(Ey)-@Value(Sy)*@Value(Ex))*(@Value(Sy_t)-@Value(Ey_t))-(@Value(Sy)-@Value(Ey))*(@Value(Sx_t)*@Value(Ey_t)-@Value(Sy_t)*@Value(Ex_t)))/((@Value(Sx)-@Value(Ex))*(@Value(Sy_t)-@Value(Ey_t))-(@Value(Sy)-@Value(Ey))*(@Value(Sx_t)-@Value(Ex_t))))

 

 

 

lines trough (Sx,Sy )(Ex,Ey) adn (Sx_t,Sy_t)(Ex_t,Ey_t).

 

I used a texteditor to search and replace variables by fme "syntax"...

 

 

3D is even worse... lol.
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1 reply

gio
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  • gioContributor
  • Contributor
  • Best Answer
  • October 8, 2014
Yeah, thase give you "apparent intersection" in 3D.

 

 

If you have like "high School Math" and a lot of stamina u could go for matrixcalcuation.

 

 

U you can use the 3DAffiner.

 

 

I made 2D affiner for inetersections...and when u convert it to fme attribute syntax..it becomes almost unreadable..but works like a charm.

 

2D lineintersect..

 

 

 

AttributeCreator [AttributeCreator]

 

Ix = @Evaluate(((@Value(Sx)*@Value(Ey)-@Value(Sy)*@Value(Ex))*(@Value(Sx_t)-@Value(Ex_t))-(@Value(Sx)-@Value(Ex))*(@Value(Sx_t)*@Value(Ey_t)-@Value(Sy_t)*@Value(Ex_t)))/((@Value(Sx)-@Value(Ex))*(@Value(Sy_t)-@Value(Ey_t))-(@Value(Sy)-@Value(Ey))*(@Value(Sx_t)-@Value(Ex_t))))

 

Iy = @Evaluate(((@Value(Sx)*@Value(Ey)-@Value(Sy)*@Value(Ex))*(@Value(Sy_t)-@Value(Ey_t))-(@Value(Sy)-@Value(Ey))*(@Value(Sx_t)*@Value(Ey_t)-@Value(Sy_t)*@Value(Ex_t)))/((@Value(Sx)-@Value(Ex))*(@Value(Sy_t)-@Value(Ey_t))-(@Value(Sy)-@Value(Ey))*(@Value(Sx_t)-@Value(Ex_t))))

 

 

 

lines trough (Sx,Sy )(Ex,Ey) adn (Sx_t,Sy_t)(Ex_t,Ey_t).

 

I used a texteditor to search and replace variables by fme "syntax"...

 

 

3D is even worse... lol.

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