Grasshopper

algorithmic modeling for Rhino

# how to convert a polysurface into a surface? (for surface population)

Hi everyone.
I'm working on a project using surface population.

I'm lofting one degree curves to make a surface with sharp edges but the
result I get is a polysurface.

I can't use that directly as a surface to populate, as my definition is using a surfaceBox component
which requires a surface as input.

Does anyone knows how to convert a polysurface into a surface? or is there any other way to get a
surface with sharp edges that I could populate?

timothée

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### Replies to This Discussion

Salut Timothée !
Have look at the previous conversation (giulio's definition):
http://www.grasshopper3d.com/forum/topics/mapping-a-rectangular-grid
you can use it to populate components on a polysurface (using the four corners of the grid for each surface).
Hi Arthur, thanks for the answer.

I'm not sure if it fits to my project... I'm concerned with surfaces with both conditions: curved parts and sharp edges (as you can achieve lofting one degree curves). I join a picture, it might be easier to see what I mean.

The solution you offered me is leading to a faceted polygonal surface, right? or maybe it's that I don't get how to relate this definition to the morph tool? I would like to morph the components according to the curvature of the surface. In addition to this, the UV divisions are linked and I couldn't find a way to control them separately (when I do it, the resulting mesh gets crazy!!).

thanks for the help.
timothée
here comes the picture. seem like something was wrong with the previous post...
Attachments:
If you just want to populate the polysurface with components that are oriented according to the curvature of the surface you can contour your polysurface and use the generated points to map components to. This gives you an even grid with each point responding to its respective surface topology. You wont be able to use this grid to form components with shared edges though - as it gets difficult to bridge individual surface gaps. To do that I would suggest maybe meshing your surface into reasonably uniform quads, offsetting those and embedding your components between. This will simplify your surface in a fairly violent fashion though.

As usual, Ive got an explanation of the polysurface grid definition on my blog: http://ledatomica.wordpress.com/2010/03/28/grids-on-polysurfaces/
Hi Gwyllim and thanks for your help!
the solution on your blog is interesting (actually I have to say that I found very interesting stuff all over you blog as well!!!)
I was trying to rebuild the definition but I miss two components, in the second part (the second pic). I don't know what are the two components before "eval"(the last one)? one is polySrfGrid, but I can't find it anywhere and the one before is a kind of slider I have never seen yet (sorry for those very basic questions but I'm still very new to GH).

thanks.
timothée
The PolySrfGrid was a label that I made for Surface closest point component - it does make for a confusing 'tutorial' and I'd be surprised if people can easily reproduce the definition. The strange slider I think is a path mapper component - In this definition it lets me 'flatten' certain parts of the tree structure.

Ive uploaded the definition for you to check against your own, or you can just use it instead. Its at the bottom of the blog post.

Thanks for checking out my stuff.
this is a great definition but does not seem to be working for me. The section component does not work. Is there any chance you could maybe sent the rhino file and gh file to my email to see how it works? Thanks
da_fenda@hotmail.com

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