Closed open polysurface which openings dont have closed, planar loops of edges

(Cam ) #1


After triming a closed polysurface with another closed polysurface, I get one closed and one open polysurface. I would like to make a booleen union on them to have only one closed polysurface, but it fails due (I guess) to the open polysurface. Is there a way to get to this final closed polysurface? Perhaps if I could close this open polysurface, the booleen union will work, but how could I do this?

Thank you very much :slight_smile:


Can you post the surfaces/polysurfaces in question? Easier to explain with an example.

(Cam ) #3

Thank you for your replay @Helvetosaur!

Of course, attached is the file.
In this file there is 4 main figure which represent the following:

  1. the one on the left is the initial model I made
  2. the one next to it is the model once I tried to make it one closed solid (but did not achieve)
  3. then, its the example I spoke about, which might help me to fix 2).
  4. finally, the one on the right is the results of the example I spoke. In other words, when I trim these two initialy closed polysurface (cf 3)), then I gent one closed and one open polysurface (see 4)). Moreover, with the showedge commande I have now some naked edged :(.

Any tips/help will be highly appreciated, thank you so much for your time.

model-quesiton.3dm (6.6 MB)

(David Cockey) #4

I copied 3 and used the command BooleanUnion. The result is a closed polysurface. model-quesitonDC1.3dm (310.4 KB)

I can duplicate your 4 using a single Trim operation. The results are as expected using Trim.

BooleanUnion of the objects in 1 fails because of the parallel cylinders which just touch along lines. Boolean operations in Rhino usually don’t work with objects which touch along lines or curves.

(Cam ) #5

Thank you very much for all these information @davidcockey.

I indeed woul dlike a closed polysurface as mentioned in your first sentence, but without the small part of the bigger polysurface (cf my number 4). In otherwords can not make 4) a closed polysurface by triming and then booleen union on the result.

COcnerning your last paragraph, this is very interesting! So it means, that we can not have a closed polysurface composed of objects that are just touching? I used offset multiple command with the distance beeing teh exact circle diameter which I used the to sweep around each of those. If I understood correctly I should do offset multiple but using a smaller distance between each object than the size of the future ‘sweep objet’?

(David Cockey) #6

BooleanUnion worked for me to create a single closed polysurface from the two objects in 4,

You can have two closed polysurfaces which happen to touch along a line or curve, but you can not combine them into a single closed polysurface. Move the surfaces so that they overlap by a small amount and you can create a single closed polysurface.

Create one closed polysurface object with several closed polysurface
(Cam ) #7

Thank you again for all your help @davidcockey
1 paragraph: Indeed, it now works for me as well… its so strange, I tried it so many time before!

2 paragraph: I can imagine that if I was trying to make a closed polysurface only with these two cylinder that touch only throudh a line. But, in my case their is a structure (closed polysurface) on which all these objects are on it. So, even in that they can not be in the same final closed polysurface juste beacause the touch through a line? I really dont understand…