ZBrushCentral

How do I cut precise curves?

ZBrush Usage Questions
#1

I’m new to Zbrush 4 and I’m having some difficulties trying to cut really precise curves, I’m using the clip curve tool.

Here's an example of the shape I'm trying to do:

[ATT=]shape.jpg[/ATT]

So far I've been trying to use a simple cube, cut everything but the thickness I want out of it using the clip brush. But then I'm kind of lost on how to cut those curves precisely :confused: Thanks!

Attachments

shape.jpg

#2

Anyone?

#3

You could make the shape an alpha? You could the alpha as a mask and extract the mesh from a plane?

If you want really accurate mechanical meshes the base should probably be made in an external app IMO.

#4

Or use the alpha in shadow box

#5

How is that done exactly?
All my attempts to use shadow box are horribly low rez and so the resulting mesh is all… well… staircased or something… like the image I am painting on the out side of the box is like 20 dpi.
Does that make sense?

#6

here’s how I would approach it:

  1. load Shadowbox128.ZTL (you can load the higher res ones, but 128 should be good enough to start with since you can always go back to the lowest subdivision if you want any major changes). Also, make sure Symmetry is turned on.
  2. block out an alpha on the Front and Right sides, and make sure its bigger than what you need, but not too big.
  3. Turn off Shadowbox and you should get the general shape, only now you’ll have enough polygons to clip with.
  4. With Symmetry still turned on, start using the Clip Curve brush and subtract from the edges. Subdivide if necessary (you’ll usually want to subdivide twice if you started with a 128 so you can get the nice crisp edges) before clipping.

My initial thoughts when you mentioned you started with the Cube was that it didn’t have enough topology on 2 of the 6 faces (mainly the poles). Despite subdividing this, it can create some undesired edges and polys.

Another option would be to load the PolySphere primitive and try clipping that.

Hope this helps.

#7

Originally posted by MealeaYing

How is that done exactly?
All my attempts to use shadow box are horribly
low rez and so the resulting mesh is all… well… staircased or something…
like the image I am painting on the out side of the box is like 20 dpi.
Does
that make sense?

Hi Mealea! :slight_smile:

Try out the following. The credit for this goes to Marcus I believe. I’m just too lazy to try and find his post. :stuck_out_tongue:

HOW TO GET CRISP TOOLS USING SHADOWBOX AND TEXTURES

1. Load the ShadowBox512.ztl from Lightbox > Tools
2. Go to Tools > Texture Map and clone the texture then export it for reference.
3. Create the shape in your 2D app to match the texture. (must be black on white and not white on black like an alpha)
4. Import into the Texture palette then go to Tools > Texture Map and click New Texture then click icon to select it and apply to the Shadow Box.
5. Press Tool > Masking > Mask by Intensity and Ctrl+click in ShadowBox to update.
6. Draw a rectangle on the side to increase the extrude.

Note: Works well for text.

Using the image that Darkalfx posted in the first post and filling the shape with black color then following the method I mentioned above, I got the following result.

new-2.JPG

#8

I agree with Nyx702, shapes like that are quickly and precisely made in a 3d modeling app. In blender it took just a couple of quick minutes.

And yet another alternative method in Zbrush is to fill that image shape with black in photoshop and save it as a psd in greyscale. Import it as an alpha. In the alpha palette invert it (so the shield shape is white). Set your desired resolution, smoothing and depth options (I set Msm to 10, Mres to 126 and depth to 16) and press the make 3d button.
Shield.jpg

Then I used the clipping brush to thin it a bit and remove the soft edges and lastly I used deformation > inflate in the negative direction just a tiny bit to harden up the side some more.

#9

ooo… very nice. I always forget about Make3D.

#10

Hya Zber!!

Everything works great till #5 at which point I crash instantly when I hit the “[color=blue][color=blue]Mask by Intensity” button, I have tried a number of times but same result.
I think this might be something I’m doing wrong so I’m going to try a few things and see what happens (I’m a little unclear on what the shadowbox object it self IS… Its not exactly a tool… I think.).

Anyhow… more on this when I have something I can describe other then “it crashed” hehe!

Cheers!
Mealea

#11

You can do this shape very easily with just a plane. Subdivide the plane to about 1 million polys and using the mask by curve brush create the shape. Use Spotlight to put your reference image on the plane. In this case you can mask the negative space around the shape faster and easier then invert the mask. Then you can extract the shape with the extract button with E Smt and S smt set to 0.