HELP! "Offset surface" splits the surface and offsets them in different directions :(

Hey,

I have a little problem. I want to offset the surface you can see in the picture on the right site. The surface on the left site is the result I got by Grasshopper. The Grasshopper code worked on easy samples without problems but on this multiple surface it didnt worked. Someone knows why? PLz help :)

Replies to This Discussion

Permalink Reply by Test123 on September 12, 2011 at 2:51pm

Hey,

I know RhinoResurf and I have a licence for it too. I created a model with resurf by a point cloud but the model is such complex that rhinoresurf cant create a single surface only a polysurface. then I did an intersection to create something directly on the model and thats the polysurface you see on the top. The problem is to create the final product automatically in grasshopper. I dont want to use another plug in again. Thats why I dont want to convert it back into a mesh in grasshopper.

I think there has to be a way to control the offset direction because the offset itself works but only in the wrong direction. Maybe there is a way to unify the offset direction.

I hope someone finds a way I am not that good in grasshopper till now :)

would be great to get a result.

Permalink Reply by taz on September 12, 2011 at 4:54pm

Your shape is very long and strip like.

You could take sections of your polysurface, rebuild the curves, and then loft.

Permalink Reply by Yoann Mescam (Systemiq) on September 12, 2011 at 5:42pm

Trying again, added a simple conversion to single surface (customized for your rhino4 file,wont work with another polysurface)

Attachments:

OffsetPolyOrReconstructed.gh, 19 KB

Permalink Reply by Test123 on September 13, 2011 at 8:38am

sry I can't open the file :( there is always an error.

Isn't there a way to fix the original offset function?

Permalink Reply by Yoann Mescam (Systemiq) on September 13, 2011 at 8:51am

What is the error ? If you use rhino5, perhaps better use grasshopper 0.80051 under rhino4 instead.

Permalink Reply by Test123 on September 13, 2011 at 12:00pm

hey, thats the error have a look at the picture

Permalink Reply by Yoann Mescam (Systemiq) on September 13, 2011 at 1:11pm

Pasted my def in yours, will perhaps work better.

Attachments:

DiscussionForumRhino4.gh, 27 KB

Permalink Reply by Test123 on September 14, 2011 at 9:55am

same error again maybe a screenshot would be easier :)

Permalink Reply by Yoann Mescam (Systemiq) on September 14, 2011 at 10:21am

Permalink Reply by Test123 on September 14, 2011 at 10:37am

ohhh that looks good would it be possible to use this for other polysurfaces too? could I loft them to a solid? What if I dont need the exactly bottom surface on the top would it be easier to create the offset? maybe I could simplify the bottom surface offset it and for the loft I use the more detailed surface. It would be ok if the upper surface is just a smoothed one. I hope you understand what iam talking about xD. if there is a 90% constant thickness thats fine too.

did you created the program by your self? looks realy difficult xD I would not be able to create it by my self I only know some basics in grasshopper.

Permalink Reply by Yoann Mescam (Systemiq) on September 14, 2011 at 11:10am

You wont be able to use it exactly as it is for another polysurf.

Some polysurfaces are not too hard to approximate with a single surface , by example yours can be cut following a single (well chosen) line and each cut is a single curve.

Resulting curves will loft in something very close to the polysurf, but you will loose the sharp angles.

Complex polysurfaces will be harder, needing a complex cut path, or wont just be appropriate for that. Thats why we have polysurfaces after all.

I dont quite understand your other questions.

And yeah, I created it, borrowing the idea of reconstructing the surfaces and copying trim from Pieter. The main difference is I construct a mesh to get clean normals (instead of using a mean normal) and use these to orient the offset. And that I dont offset the reconstructed surfaces, but the original untrimmed ones (reconstructed ones are used to define "real" normals only).

Permalink Reply by Test123 on September 14, 2011 at 12:43pm

maybe there is a way to simplifiy the surface (reduce the number of faces) the thing is, the upper surface (the result of the offset) doesnt has to be sooo detailed like the bottom surface.

If I could simplify the surface maybe the normal offset function works too.

And then when I create the solid (bottom surface, upper surface, walls) I could choose the detailed bottom surface.

This should all happens automatically in Grasshopper :D

I hope you understand my idea :)

It is only important that the model I create fits on the model i created with RhinoResurf.