ZBrushCentral

Create Shell Error - answered

ZBrush Usage Questions
#1

I was excited to see the new “Create Shell” feature and am attempting to hollow out my character for use with 3d printing. However, my model is experiencing a blow-out in the back (see attached images) I first tried a single negative cylinder, then attempted two cylinders and got the same results. (both exhibited the exact same hole openings in the back)

Incidentally, is it possible to create a custom shape (the bottom sole scaled inwards a bit) to use as the negative mesh when creating a shell? I’m going to get some of these printed with the metal materials from Shapeways, and they recommend the bottom be fully opened.

Thanks for any suggestions/workarounds. Btw, Dynamesh is awesome - I used it to “weld” all of my original Maya geo (that was designed to be interpenetrating) with perfect results.

-Steve

Attachments

sb_front.jpg

sb_rear1.jpg

sb_rear2.jpg

#2

Alright, so I got a custom brush to work as the negative mesh, however, still getting that blowout in the rear of the figure. I used the default thickness (4) and then tried doubling to 8 with no luck. Argh!

Any ideas? This is on a pretty high-res Dynamesh. I suppose I could try using Decimation Master to bring it down a bit, then try Create Shell again.

-Steve

sb_rear3.jpg

#3

I have tested the shell function with a DynaMeshed SuperAverage man and it work as it should.
Can you post an image of your mesh with the negative insert BEFORE pressing the Shell function?

Tip: Activating the Polish option will result in smoother interior surface.

#4

Here’s what the negative insert brush looks like before attempting Create Shell. I’ve also attached an image of what it looks like coming out from Maya. Btw, is there any easier way to line an insert brush up? I was hoping I could load it as a sub-tool (already in position based on Maya’s layout) and simply set it to negative for the cut. Instead, every time I try this out, I have to drag it out and fool around with Move, Rotate and Scale to put it into proper position.

Thanks,

-Steve

sb_before_CreateShell.jpgsb_from_Maya.jpg

#5

I tried a few more things - primarily, lowering my DynaMesh resolution from 1024 down to 256. This seems to have worked. I did try 512, but was still getting the hole.

However, now DynaMesh effects the entire mesh (because I lowered from the max resolution) and re-topologizes with a lower res, causing some less-than-smooth areas where the welding of geometry intersected. (see image)

Ideally, this may be fine, as I’m going to print these out no larger than 3". I just want to make sure the detail will hold up tight with the higher micron printers.

-Steve

sb_post_Shell.jpg

#6

Thanks. The placement of the negative inserts looks fine. Do you experience the same problem if you re-DynaMesh the model in a lower resolution? If a low resolution causes the same problem then, if possible, upload or send me a private msg with the low res attachment and I’ll run some tests.

As for placing the insert mesh…
I see that you already have the insert mesh in the right place. If it has a unique groupid all you would need to do is to enter transpose-move mode, mask all except the inserts, press CTRL+ALT a slightly drag the insets. The duplicated inserts will now have the proper groupID (white) and they will ‘cut’ when you press the shell command. You will most likely would want to delete the original inserts in order to avoid conflicts with the ‘cutting inserts’.

#7

I had JUST edited my previous post trying out the lower res and it did work. (See above) However, because I lowered the resolution, it re-topologized areas that I thought it should not effect. Doesn’t DynaMesh only update the changed (in this case, the hole opening and INTERIOR surface) regions?

I think this will be sufficient for getting a 3" print. I’d like to nail this workflow down as I’ll be using this feature a lot as I continue with my toy prototypes.

Thanks!

-Steve

#8

Just a comment about the Dynamesh resolution and final mesh quality: it is strongly advise to work in a lower resolution than 1024 with the Dynamesh in most usages. Before hollowing, clone your model, then stay between 128/256 of resolution to create you shell, and when your shape is done, apply a couple of subdivion smoothing.Then, project your original mesh on the Dynamesh object.
The Dynamesh must be considered as a low to middle resolution mesh.

#9

Thanks for the workaround! Btw, how do I project the original (cloned) mesh back on to the DynaMesh object?

-Steve