Problem with Boolean Intersect on figure

[ChrisCD]

Hello -

I've been asked to visualise a piece of sculpture that will be created from flat sheets layered to make "slices" through a human figure. (A bit like an MRI scan)

So as a test I've exported a figure out of Poser 3D and imported it into Cheetah (7.4.1) but whenever I try to do a boolean intersect on the figure I get no results - the objects just disappear. I can get a Boolean intersect working on other objects, so it's not just my ineptitude with Cheetah that is the problem! The problem seems to be with the geometry (or complexity?) of the figure.

I did search the forum and the issue has been touched on before ("Boolean operation on a complex volume", March 2019) but the answers given there aren't helping me with my object.

I wonder if anyone could shed any light on this? Here is a link to the figure in case someone can help!

Thanks in advance,

Chris

 

[Charless]

Your figure is not watertight, but Ive no clue how to fix that, I gues you have to find the (but) hole and close it

 

[ChrisCD]

Thanks. I'm not 100% sure what that means, but I'm guessing that it means there is a problem with the way that Poser has exported the figure. grrr

 

[Charless]

try another figure, I am not sure if Poser creates watertight models

 

[Charless]

 

[ChrisCD]

Thanks Charless, yes you are quite right - I can make it work with other objects (I had mentioned that in initial post!) so you have narrowed down the problem for me! The trouble is I really need to have good control over the pose of the figure so Poser is the ideal tool for that. So I need to rephrase my question: How do I make Cheetah Boolean-friendly figures from Poser!!! Thanks again.

 

[Charless]

Maybe you have to ask the Poser forum guys like: How do I make watertight figures in Poser

 

[ChrisCD]

Yep - guess where I was just heading ;-)

 

[Charless]

Be carefull, C3D will shut down after applying multiple boleans in/on high poly objects (at least that my experience)

 

[ChrisCD]

Be carefull, C3D will shut down after applying multiple boleans in/on high poly objects (at least that my experience)

Thanks for the warning!

 

[ChrisCD]

Looks like whether it is watertight or not isn't the answer anyway. :-( On another model that does work with Boolean intersect, I checked to see if it was watertight - and it wasn't.

Back to drawing board! But thanks again for the pointers.

 

[Charless]

please check out: go in polygon mode - select one polygon and try to drag it from the mesh - or hit cmd+G (for group selecting) when all turn red it´s one mesh

 

[Charless]

please check out: go in polygon mode - select one polygon and try to drag it from the mesh - or hit cmd+G (for group selecting) when all turn red it´s one mesh in this case its not all equal red color so its not one mesh

 

[ZooHead]

I think it's the eye holes as far as water-tightness, although there are teeth and tongue that should be removed.

The other problem is it's all triangles, but with some fiddling it works.
It may help to set the smoothing of the man to Normal Break.
This is because the Boolean creates a Crease at the cut and Normal Break prioritizes the Crease.
That keeps the smoothing from smearing over them.

 

[ZooHead]

Water-tightness is not required for Boolean operations to work, but things will behave differently.
Try to subtract a Cylinder from a Plane and you get an extrusion sticking out of a plane.

 

[ZooHead]

And here's a example of what the Normal Brake setting does.
Because of the angle of the cylinder, and the smooth angle, the smoother will try to smooth.

 

[Swizl]

One good thing to do when bringing a mesh in from another app, is to run an Optimize on the mesh. Be careful though of the scale of your object vs what the optimize settings are set to. They need to be balanced with each other, or the optimize might chew up your mesh. If you're mesh is really small, then you need to use smaller increments in the optimize settings. Sometimes you have to play around with it to get good results. Usually meshes, especially character meshes, that come from other apps have grouped areas of polygons. For instance, the head might be one group, the arm another, etc. A lot of times optimizing this will help solve a meshes water tightness. If the mesh comes in as different objects, you can use the Merge command to combine them. And then run the Optimize command.

One other way to split a character in half (as long as it's already symmetrical) is to go into ortho front view and then enter point select mode. Use area select tool (I have mine set with a keyboard shorcut of "A" I use it so much) to select half the points on one side or another and then delete them. You will have an opening in the middle of the body, but you can create a n-gon to fill it.

Also be aware, that chopping up the mesh like this might destroy any UV maps.

 

[Charless]

And here's a example of what the Normal Brake setting does.
Because of the angle of the cylinder, and the smooth angle, the smoother will try to smooth.

View attachment 36821

Hi Zoohead, I just wanted to know: Are you working in a different version of C3D, because of the hierarchy of your boleans. When I try your method my boleans does not work? And your Bolean Icon is blue with green, mine is bleu/orange

 

[Helmut]

Good Morning!
There are two Booleans, one working as a modifier, the other as a creator. You may want to experiment a little to get an intuitive feel on these tools. Both can add, subtract and intersect, but they are applied somewhat differently.

 

[Helmut]

* There is an elaborate sample by Frank B around somewhere which shows Booleans on a quite complex engineered component of an engine using parametric objects only. A query on the forum may help.