ZBrushCentral

Absolutely at wit's end

ZBrush Usage Questions
#1

I am in a bit of a conundrum and I’m not very far off from pulling my hair out.

One of the things I do as an artist is make models for 3D printing. Most of the time my tasks are a snap. Between Blender, Photoshop, Zbrush, Netfabb and like TWENTY THOUSAND other programs, there is no shortage of tools at my disposal to aid in efficiently putting out good, printable 3D models. However, there is one extremely vexing problem I frequently encounter -hollowing out very complex models such as this: http://bobbie-the-jean.deviantart.com/art/Temp-post-2-415262765

There are MANY ways to hollow out simple models but for more complex models, things become more difficult. The methods I know of for hollowing out complex models frequently result in some rather irritating issues. Here are the problems that arise from the various methods of hollowing:

1.) Dynamesh: One can easily hollow simpler models out by using what essentially amounts to a subtractive boolean with a negative mesh. However, this does not work on more complex models because details offset with shrinkage and you end up with non-uniform thickness, holes, messy geometry, and intersections. For this model I want a nice inform 3mm thickness.

2.) Negative inflate: Duplicate model, negative inflate, smooth, bridge brush between the inside and outside walls, BAM! Except that this method creates A LOT of intersecting geometry and I have no choice but to go in and correct it by hand. The problem there is that with complex models, there could be hundreds of thousands of points where the thickness falls below 3mm and I couldn’t possibly find them all by hand. It would be really nice if Zbrush had some way of measuring wall thicknesss. :\

3.) Extract: Ultimately, I seem to run into the same problem here as I do with negative inflate. The geometry around finer areas goes all wonky and ends up sticking out all over the place or I end up with balloonification. I don’t want that. I want a nice, uniform thickness. I realize I might have to do some finagling and manual labor around finer areas and that’s fine but if I could just get that uniform thickness around MOST of the model, I would be VERY happy. The real problem here seems to be all the nooks, crannies, and sharp edges.

Does anyone have any suggestions? I realize I’m probably not going to get a magical easy-fix solution but at this point, I’m just hoping there is something more efficient than doing the whole thickness manually.

#2

Come on. Someone has GOT to have a way to do this.

#3

You don’t mention the Dynamesh>Create Shell option. Have you tried it?

See the bottom of this page:
http://docs.pixologic.com/user-guide/3d-modeling/modeling-basics/creating-meshes/dynamesh/methods/

#4

I’m Aware but that doesn’t accomplish what I want. I need a uniform thickness. I want the model to be pretty much uniformly 2mm thick. There’s no way to do that with dynamesh… At least not that I know of. :\ This is very frustrating.

I’ve tried using a scaled down negative mesh but that displaces the geometry non-uniformly and I don’t end up with that nice 2mm thickness.

#5

If you mean absolutely uniform and absolutely 2mm thick then ZBrush is simply not capable of that and you’ll never achieve it using any of the methods you describe. You will need to use a specialist app for doing it, precisely because of the problems you describe - the inner skin can’t be a scaled down version of the outer skin. The Create Shell option is the best solution that ZBrush provides but that won’t do for absolute precision in thickness. It’s intended to reduce the material used in 3D printing, not produce a perfect inner shell.

#6

Dang. :\ People over on the Blender forum are pretty much saying the same thing. Maybe someday 3D printing will become more commonplace and the need for this kinda thing will become commonplace but (if ever) until then, looks like I’m going to have to suck it up and do this crap by hand. :\ I wish I could communicate just how frustrating and tedious this task is. It’s not like I mind detail work. That’s what I’m known for! But this brings tedium to a whole new level. XC

Bummer.

#7

Usually people do hollowing task with Meshlab. It´s free and can do a great job calculating an exact distance from the surface.
I use Zbrush for all 3D printing process. Because in most cases when hollowing pieces you don´t really want to have some tunnels that makes impossible to remove or void residual material. So in the best case you have an acurate inner shell i think is not allways is the solution at 100%. But Zbrush offers you all the power to edit this inner part as you modelled the outer one.

#8

I intend to try out Meshlab. :slight_smile: Here’s hoping. I realize it’s not going to do ALL the work for me and that’s fine. I just need something to start from. I also ignited a 3D printing poll over here http://www.zbrushcentral.com/showthread.php?182046-POLL-Would-you-Like-To-See-Comprehensive-3D-Printing-Tools-in-Zbrush&highlight=printing+tools but it kinda fizzled. Didn’t really get much response at all. I dunno if maybe I stuck it in the wrong place or there really isn’t that much interest for it but either way, I would love to see more tools for 3D printing, not just in Zbrush but in general. I know one of the first tools I would love to see is the ability to generate thickness as determined by input. Would make my job A LOT easier and more efficient. XD I am constantly having to hollow out complex models and let me tell you, that equates to A LOT of time I could be spending on other things. O__O;

#9

Could you dynamesh subtract your object from an enclosing cube leaving a hole so that you get a cube with your shape as hole in it? I think you could inflate that and re dynamesh to get a clean inner shape for you model. Then you should be able to to dynamesh intersect that shape with your original object to get you shell.

#10

Why does it need to be 2mm thick? About what size are the general dimensions of your print model? 2mm could be thick enough or too thin depending on your object’s overall size.

#11

That I need 2mm thickness in this case isn’t the issue I’m trying to communicate. The issue is that hollowing out complex models in such a way that allows for minimization of cost while maintaining structural integrity is a profoundly frustrating exercise in extreme tedium. In this case, the reason I need 2mm is because 2mm is the minimum wall thickness for the material I want to print in. 2mm should be fine considering the structure. There are no unsupported structures or exaggerated overhangs.

My problem is ultimately that this kind of task is extremely tedious and I come up against it frequently. Unfortunately, 3D printing isn’t too big at the moment and the demands for this kinda thing probably isn’t too… I wonder if I could try panel loops. O_____O …Brb.

…Oh my holy god. Did that really just… happen? Panel Loops. !@#$%^&*ING PANEL LOOPS. WWWWHHHHEEEEEEEEEEE. Well. That um. Hm. Panel Loops. Who knew? I mean it ain’t perfect. I still have some crap mess I need to clean up but that more or less did pretty close to what I was hoping for. Let’s just do some checks on that to make sure. Crosses fingers

-_______- Nope. It’s not all that different from the other methods… just a little faster. Bummer.

#12

Try using Blender and its Solidify Modifier.

http://cgcookie.com/blender/2013/02/04/modeling-3d-printing-shapeways/

#13

I tried that and I actually posted a similar thread in the Blender forums. The solidify modifier causes the same problems. I end up with a lot of mess and a ballooning issue. :\ I’m guessing at this point there is no easy fix for this, at least not at present. I’m going to try Meshlab but really, not going to hold my breath.

#14

Do you have a sample file you could send me? I could look into it and try a few different things.

#15

This is what I’m hollowing out atm: https://www.shapeways.com/forum/index.php?t=getfile&id=46022& That was all done by hand and it took a whole day. -___O And I’ve still got more work to do on that. I could send you a similarly complicated model just to see what you could come up with. If you don’t mind taking the time, that is. That would be fantastic. :slight_smile:

#16

Just wanted to bump this thread and see if there have been any advancements in the last couple years. I’m in the same boat. I have to do wall thickness of 1.5 mm and not sure how to get that accurately. Its for a toy company and the tools I have at my disposal are maya and zbrush. I’ll download meshlab and check it out.

#17

I think there’s a way to do it that’s a little wonky but it has worked for me. I can’t remember exactly how it works because it has been a while since I’ve used it but basically, you need to insert a sphere into the base and hit “create shell” or maybe it’s just “shell.” There’s a more detailed explanation in Zbrush’s documents, I believe.

Unfortunately, Zbrush’s measuring tools aren’t really all that great BUT I think there is a way to measure it out using the transpose tool. You might need to do-undo-redo-undo-redo that a few times before you get the right thickness.

I hope that helps. :slight_smile: