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I have a flat roof as polygonz feature that has dormer windows (I hope this is the correct expression) as additional polygonz hovering over it.

 

For drainage calculations I would like to have the flat roof polygonz with holes where the dormer windows are and additionally the dormer window as they already exist.

 

I tried to make a sketch of what I mean:

 

 

resulting Area A = A - ( B+C+D)

 

Total roof Area = Area A (with holes) + B + C + D.

 

 

AreaOnArea overlayer gives me weird looking results with a lot of artifacts. I tried to 2Dforce the roof and clip it like that but then I am unable to make it 3D again since there is no attribute I can use for it (because then I would merge the unclipped Area A again).

 

 

Thanks for your help!
Unfortunately there is no editing function here... In short, I want to penetrate Area A by Areas B,C,D or generally, penetrate Areas by Areas that lay above them.
Hi Simon,

 

 

 

This operation u want to do is basically a projection of the windows on the roof.

 

The roof is flat. Therefore u can remove the z values of all the objects and clip them.

 

then u can replace the z values of the (flat) clipped roof, with the original z value (wich makes it 3D again).

 

 

U wil be clipping the projected profiles of the windows of course.

 

 

 

Gio
Hi Gio

 

Thanks for your advise! Unfortunately I just realized that there are all kinds of roofs involved and not only flat ones... So I think I still project all the features to the ground, but how do I get them to 3D again.

 

Meanwhile I tried out the geometry reader but I am only able to restore the original shape and not the 2D clipped one (logically, because i read it in 3D).

 

Thanks for further help!
Hi Simon, the SurfaceDraper (Group By: ID of Roof) might work.

 

 

Takashi
This seems to be better.

 

 

Thank you very much Takashi, I think you led my on the very right track! However I still get some weird results concerning gabled roofs and also at some flat roofs. Do you have any idea why this could be?

 

before SurfaceDraper (green = roof, red = "window"):

 

 

 

after SurfaceDraper (draped features:

 

 

 

another error after DonutBuilder (the area in upper left corner should be "flat" without artifact area connected to the areas on the right):

 

 

 

Thank you for your inputs!
I did some other tests where I extruded my windows with a negative amount and then tried to clip the roof polygons with these solids. Unfortunately it does not seem to work. Is it even possible somehow?
If the window intersects with boundary of the roof, it cannot be a donut hole. How about the Clipper and SurfaceDreaper?

 

 

This is it! Thank you very much, Takashi.

 

 

Kind regards. Simon

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