Hey all,
I’m testing out the transfer between this two apps. (the reason I got Zbrush.)
-Created a revolve object in Rhino.
-Export as .OBJ
-import into ZB. The model looks like a low poly count.
I suspect it might be the nurbs to poly translation. Any tips on keeping my model smooth between these two GREAT apps???
Much thanks guru’s
-Dooki 
Ask Marcel !
Pilou
In ZBrush, you can set the Tool>Modifiers>Smooth slider to 100. This activates subdivision smoothing, which increases the number of rendered polygons. There’s a slider right next to that which allows you to increase the amount of smoothing that takes place.
Rhino probably has features to accomplish one of two things:
a) Smooth a polygonal model
or
b) Convert a polygonal model back to NURBS.
You should check your Rhino documentation to see what is possible.
An analogy for how to look at the difference between polygons and NURBS is that polys are like raster images and NURBS are like vectors. Because NURBS are based on splines, they always remain smooth no matter how closely you look. Polygons, on the other hand, can only be smoothed by increasing the number of polygons to a point where you no longer notice the edges.
hello dooki!..when you export from rhino, you have the control on the amount of polygons exported. increase or decrease is a matter of “heavy” computer, as of course the more polygons, the more weight. you have on ressources, at rhino site, a free plug in to import obj in rhino; there is also a not free one, i didn’t try, the free utilitie works perfectly; to import from zbrush, no problem, but you are going to have an heavy (HEAVY) mesh, and you can do very few things in rhino on mesh; to convert again in nurbs, no aurick , there is not a button! in fact it’s a very difficult process, ther is a plug in very expansive that pilou and another member have linked earlier, and ther is ythe method i’ve explained in precedent topic; it’s work better, it’s free, but it’s very tricky, you have to “look” closer at your curves… hope this helps! amitiés M.
Aruik, Marcel-
Thanks a bunch for your help. I will try them out! Marcel, my goal was to tweak a rhino model in ZB, import it back into rhino and send it out for prototyping. Do you have any experience with this?
-Dooki
For prototyping, you’ve got it made since that requires very high numbers of polygons. For that use, when you are working in ZBrush go ahead and divide the mesh as necessary (Tool>Modifiers>Deformation>Divide followed by Smooth 100). Just be aware of your polygon count (which you can see by mousing over the model’s thumbnail in the Tool palette), and try to keep it under 250,000 for best results.
When done, you can export it from ZBrush to Rhino and from there export it again as the STL format.
I know a good many people who have used ZBrush very successfully for rapid prototyping work.
WOW! you are DA-MAN! Thanks for the much for the help.
-Dooki
hi dooki,
All question have been pretty much answered I think. I have access at uni to Paraform and this is primarily how I convert my zb models to nurbs or more importantly to an oranised lowpoly cage for use in generating Normal and Displacment maps.
You can however do this in rhino , but it is a more laborious process. Basically if your export a highpoly mesh to rhino you can draw nurbs curves over the surface using the snap to point tool…I think there is also some function to work with point clouds…where you can actually project cuves on to your point cloud model…which is a huge time saver.
On that note Aurick…I have tried do hybradise my work flow using a mixture of appz including zb. For simple objects such as mice , computer screen mobiles phones its a great work flow and much faster and better then my normal workflow. How ever in trying to model larger and more complex objects, where there are transition of sharp and soft surfaces I found it increasing difficult to to control the mesh with zbrush.
My work flow btw is as follows:
1 Build a lowpoly cage of your object in a polymodeller such as wings or maya, desribing the correct planes and hard adges of your object.
2 Take this model in to zbrush and add curviture and volume to the model.
3 Export and Surface with Nurbs
4 Export Nurbs model to Nurbs program like rhino and add all the extra features, like grooves and buttons, fine detail that would be high tedious in zbrush.
6 Export the object again , this time higpoly and resurface in nurbs to line up all the Isoparms and eliminate cracking and trims problems.
If possible may I ask if you have some examples of work that has been done using zb for RP and maybe some stratagies and or methods that we can use to gain greater control when creating hard adges and smooth surfaces for complex objects. I think there are huge advantages in using zbrush for this type of work and I’m intersted in developing the workflow.
THanks and good luck with your work dooki
Kircho
Hello All,
I have followed discussion on Polys to NURBS conversion for several years, and it is my understanding that now there are a few high end apps ($10,000 - $15,000+ US dollars) that will do this automatically.
If Rhino is able to quickly generate a NURBS model from polys, please clue me in. I am aware of a plugin for Rhino called Smurf that assists in generating spline curves from a polygonal model for creating NURBS patches, and it still requires a lot of work.
There is now a plugin for FormZ 4.0 that will do automatic conversion, though it appears to be somewhat fussy about the geometry and sufficient point density of the mesh in order for it to yield good NURBS patches. (This is based on some comments from users on the FormZ forum, rather than my own firsthand experience.) I plan to purchase this plugin soon since it is reasonably inexpensive (about $300) if I can’t find any other low cost alternatives.
NURBS are not necessarily a requirement for producing prototypes. In fact most machining systems convert the NURBS surface into polygons or triangles in order to calculate the toolpath, and with sufficiently small facets, you can’t tell the difference.
The advantage of NURBS for producing physical models, it seems to me, is in creating objects at many different sizes, without having to worry about the polygon resolution. This parallels the transition from the use of bitmaps fonts to outline fonts (ie. PostScript, TrueType etc.) several years ago. The advantage of outline fonts is that you only have to be concerned with having one font to print it at any size.
So along with the flexibility in creating organic surfaces, with NURBS we have a resolution independent representation of a model.
Anyone with additional info please comment. Software advances move so fast and its impossible to keep up with all the new developments!!!
Chris
Hi Cris
Ask to Marcel to describ precisely his super tricky method (if you are ticky too) 
and with a plugin free 
Pilou
Just say that Rhino version 3 can exprt obj format(i just did it)
there is a way to convert from a poly mesh to nurbs in rhino. It is a pretty much un documented command, and doesn’t work well with hi-res meshes. It also takes a while to do do its thing, and doesn’t necessarily make the best nurbs objects. With all that said, the command has to be typed into the command line, it is meshtonurb(s). Can’t remember if it has the s or not, but one of them will work for you. Hope that helps
HI EVERY BODY !
i HAVE FIND A FREE CONVERTER / 3dwin here
1- eXPORT IN 3dS
2- OPEN 3DwIN CONVERT TO OBJ
export options (replace THE SIZE VALUE (1) TO (10)
3- import in Zbrush this new file .
4- enjoy !! you can subdiv
Hi Guys,
Please help!
Sorry i am a very new user of Zbrush core…
Can someone please help and let me know how it work when importing a Rhino file to Zbrush core…
Is this a different procedure then import to Zbrush.
I can only find tutorial that if on Zbrush4R8
And please if someone knows can you tell me like step by step(dummie style) 
Kind regards,
Martine