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Old 18th March 2018, 04:49 PM   #1
LumpTom
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Default How to fid "non-manifold" an "open edges" objects

Hi all,
I am using AC3D for more than 10 years, but still have trouble with AC3D object "consistency" related to boolean oerations and now, when I fall into 3D print world, also with related "non-manifold" objects.

I feel quite big AC3D insufficiency regarding some letīs say object checking or help to identify problematic places. When complexity of builded object increases, mostly I get to the moment, when I am not able to do boolean operation duet to "open edges" and I am not able to find where the mistake is. Mostly these inconsistences also results in not printable objects as slicer software reports "non-manifold" object.

So, my first question is, it is there any way in AC3D to identify and fix these things without using some other software, which I must such object import in and do check and fix? (for example Blender has this option)

I know that there can be several reasons that object is not manifold (and much of them probably means also inappropriate for bolean in AC3D) - for example self intersecting object, separate innner object, holes, inner "T" faces, overlaping geometry ... and so on. Anyway, when AC3D is able to identify some of them, why is not able at least to show, where they are to be possible to fix it manually?

And second question ... if answer to first question is "not at this time", is there any possibilty have this feature in the future in AC3D? (It is probably question for Andy or his colleagues...)

I will be glad for any advice from local experienced modellers.

Regards,
Lumptom
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Old 19th March 2018, 03:26 PM   #2
Andy
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Default Re: How to find "non-manifold" an "open edges" objects

Hi Lumptom,

I have a few suggestions.

Switch to Surface select mode, select-all (press Control-a) and try Tools->Select-leaky-surfaces.

In Vertex select mode, select everything again (or the area you are working on) and use menu Edit->Select-Vertices->Boundary.

They will find the places where there are holes/open-edges - which can be created from boolean ops, especially multiple booleans. They may not be entirely obvious but if you move a surface which is leaky, you should see a hole appear at one of the vertices.

To fix these, you may be able to delete vertices or combine surfaces to remove edges.

Also, you can set all surface to single sided. If you then look around the models and see any gaps, some surfaces will probably need their normals flipping. Switch on display of normals too - that can be handy.

Also useful would be to optimize surfaces (to remove any duplicate surfaces) and optimize vertices.

If you haven't seen it - this may be useful: https://www.inivis.com/3dprinting.html
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Old 20th March 2018, 02:14 AM   #3
LumpTom
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Default Re: How to find "non-manifold" an "open edges" objects

Many thanks Andy .... GREAT !!!I

I did not noticed leaky surface option in Tools menu and also did not know that select vertices - boundary can be used for identify open edges. Now all will be much easier !!! Because I know how to fix all the stuff, but I did not know how to identify it in the model.

Regards, LumpTom
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Old 25th June 2018, 10:36 AM   #4
gezueb
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Default Re: How to find "non-manifold" an "open edges" objects

The boolean algorithms seem to have a precision issue with small parts (>1.0) I had troubles for a long time until I scaled up parts to grow substantially. Then the boolean functions leave much less leaky objects. If neccessary, one can scale them down again afterwards. My X-Plane objects were scaled in meters. Scaling them to mm gave much better results on boolean. Cannot fathom why AC3D does not use higher precision for a 64 bit machine. Probably speed is an issue.
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