ZBrushCentral

Working from Rhinoceros5 to ZBrush and back

ZBrush Usage Questions
#1

Hello, I am new to ZBrush, and currently using Rhino5 to make basic forms (usually for jewelry purposes where scale and measurements are critical). Then I import a .obj file from Rhino into ZBrush and work with it there to make organic sculpted changes.

As you can see from my pictures, for this project I got it decently smooth for a small casting. But when I try to divide the geometry it creates rips in the mesh where those original crisp seams were from Rhino. What can I do in the future to let the geometry divide without mesh rips? Do I need to blend the seams within Rhino? I tried to subdivide straight away on my original Rhino import, but it still made rips at those seams.

For intricate bas-relief along with gemstone placements for a couple projects on deck, I will need more precise and smooth sculpting, but upon the geometrically precisely sized Rhino shapes.

Thanks for any help!DragonHammerFromRhino.JPGDragonHammerBeforeDivide.JPGDragonHammerAfterDivide.JPG

Attachments

DragonHammerFromRhino.JPG

DragonHammerBeforeDivide.JPG

DragonHammerAfterDivide.JPG

#2

In ZBrush, go to “Tool > Geometry > Modify Topology” and click “WeldPoints” before you subdivide.

#3

Thank you very much!

#4

I used Rhino V5 & ZBrush.
I normally import as an .OBJ, unify the model & DynaMesh. To get it back to Rhino I use Decimation Master and export as an OBJ.

Might have to rescale once it’s back in Rhino, but that isn’t difficult. To be honest, if sizing is critical on a part I will (where possible) add the critically sized item in Rhino in the final stages e.g. Cutting a hole to fit given tolerances.

#5

Thank you for your tips! I will give that Decimation Master a whirl. Does that reduce mesh size while preserving detail?

When I brought the dragon hammer back to Rhino, it was a little slow on my old laptop. Is it necessary or desirable to convert the .obj mesh back into NURBS? Or do meshes boolean as well, or better, or worse, than NURBS?

#6

Hi Carved Metal, sorry it has taken a couple of days to get back to you. To answer your questions:

> Thank you for your tips! I will give that Decimation Master a whirl. Does that reduce mesh size while preserving detail?

Yes. However, I always save a Decimated model as a separate file just in case I want to change something later. It will give you a triangulated model, ideal for prototype applications. However, if you want IGES or solid models… ZBrush will not give you these. If you export a Quad mesh (ZRemesher) you can use T-Splines to make a conversion but I hope your PC is a good one because Rhino gets very twitchy with large files!!

When I brought the dragon hammer back to Rhino, it was a little slow on my old laptop. Is it necessary or desirable to convert the .obj mesh back into NURBS? Or do meshes boolean as well, or better, or worse, than NURBS?

Converting back to NURBS is frankly a pain in the ****! I’ve done it, but I avoid doing it because it takes too much time to make products viable in most cases. At the very least you are going to need T-Splines.

I work with MESH if I need ZBrush for organic forms. Do as much Boolean work in ZBrush except for the tolerance sensitive work. The MESH that comes out of ZBrush can have ‘intersecting triangles’. These will often result in errors in Rhino V5 and Booleans will fail.

If your end game is to use prototyping methods in your production process then you’ll be fine to work with MESH. Good luck!

#7

Quick Tip: If the intersecting triangles give you problems you can ‘trick’ Rhino. Depending of your tolerance settings, nudging the object that you want to Boolean by 0.001mm can solve issues. The problem arises because two points are meeting exactly… you need to make them not meet… :wink: