Grasshopper

algorithmic modeling for Rhino

Hi, I am new here. Thank you for a great plugin and forum!

I have a problem with the "offset mesh" function in weaverbird. I had the same problem in Rhino and thought it could be solved in GH, but I can't find my way....

The overall problem is about overlapping surfaces, because the shape is very curved. I need to keep the outside of the mesh and need to offset inside the mesh. Do anybody know how to solve this?

In this case it could be great to offset in the direction only towards an axis in the center of the shape... 

- and how do you make the offset solid?

Hope someone has an idea...

 

First image is the shape with no offset

second image is with offset showing the overlapping surface

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Replies to This Discussion

bake the component and check for overlapping... sometimes the preview from grasshopper it isnt accurate.

 

another option is the mesh thicken in WB, try that.

Hi Manuel, thank you for your reply! I tried to bake, but the surfaces still overlap. I think the "Mesh Thicken" gives the best result. Thank you for reminding me. So if I have to choose, it will be the tool to use...though not quiet satisfying...but I will make some 3d prints now to test it in reality...

I think it could be useful to change the directions of the normals, since it seems like, it is the normals, which control the direction of the offset, - but I don't know how to do that. I tried in 3d max, but was not quiet able to control it. I want all normals to point towards the center of the objects/ e.g. Y=0 and X=0 from their position at the Z axis... but how to do that...?

Thanks!

 

#1 is without

#2 is mesh offset (baked)

#3 is mesh thicken

 

 

Have you tried using the "mesh unify normals" component?  There's also a "mesh flip" component that might be useful for making sure you're mesh always offsets in the desired direction.  

 

I forget if they're both native to grasshopper, or if they come with [uto]'s mesh analysis and utility components (which you can and probably should get anyway because they're awesome http://utos.blogspot.com/2011/07/mesh-analysis-and-utility-componen...), but if anything will help you control the mesh in the way you'd like, I think it will be these.

Thank you for your reply! Thanks. I have tried these component and I think you are right they come from [uto]'s mesh analysis and utility components. I have tried to control the normals with these components, but have not succeded. I don't know what tool in GH that can control the normals' angle in such a way except from that I can flip and unify...hm...but the setup must be with these components and some which can attract them to a spline or dislike....

Thanks!

Hi Flemming,

 

thanks for posting this question.
Do you think you could also attach a model with some arrows showing where the problematic areas are?

I'll see if I have suggestions for these.

 

- Giulio

Hi Giulio, Thank you for your reply!

It could be great!...

I hope this is helpful otherwise correct me:

Image 1 is the profile of the shape without offset.

Image 2 is the profile with offset, - and it is actually the different or "extra" in this profile, which is the problematic areas. (one area is exemplified with red arrows, - but it is the different as such). The offset seems to be made in 90 degrees and of course it will cross the surfaces...

I would like the object only to be shelled inside. I need a thickness to make a 3d artefact by 3d printing (which will be a container). If you suggest another approach it is just fine. If it can be done with offset I need it to executed as a solid shell.

If the "mesh thicken" tool is used it could be great if it just made it thick in one direction - inside, but it makes it at both sides of the surface..also if you work with negative numbers...

Hope you have an idea. Thanks anyway for your time and reply!

 

 

Ok, I think I understand now. Self-intersection removal would be interesting, but at the moment wb does not perform it, nor I think it is done by the Rhino mesh offset function.

One possibility would be to offset the surface first (your model is a surface, right?), and then adjusting it manually. This is obviously taking more time, but I am not aware of other possibilities at present.

 

- Giulio

Hi Giulio, Thank you for your reply. It is a good term for it "Self-intersection removal". That's what it is... What I know the Rhino mesh offset function does not have it either. Though it easily could be useful I think when offsetting for making a shell thickness.

It is a mesh surface and a way might be to do it manually - but very time consuming and complex in this case, I think. I might have to use the mesh thickness tool... or hope someone else know how to do this. Thank you anyway for your time!! 

Dear Flemming,

we have a very similar problem at the moment with a complex object.

Do you have any solution so far to make rather automatized than manually?

Thanks for any hints!!

Hi, 

Unfortunately I do not have any solution to this problem yet....

Flemming

Hey Flemming,

I am having exactly the same issue, with a very similar shape to yours!

Did you figure it out back in the day?

Thanks! 

Stavros 

Hi Stavros, 

Unfortunately I still don´t have any solution and have left the issue for a while, though it still have my interest...

So please return if you hear about a solution...so will I...

Thanks!

Flemming 

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