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boolean OBJ
Posted: 07 April 2013 09:19 PM   [ Ignore ]
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whenever I make even a simple object with a boolean cut and export to OBJ, hex crashes.

Any hints?

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Posted: 08 April 2013 04:33 AM   [ Ignore ]   [ # 1 ]
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Sorry don’t use Hexagon but I do know never to use Booleans for export…ever. smile

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Posted: 08 April 2013 11:25 AM   [ Ignore ]   [ # 2 ]
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Boolean’s are the spawn of the devil.  wink

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Posted: 08 April 2013 11:31 AM   [ Ignore ]   [ # 3 ]
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select all and triagulate ngons I guess
(I do not model in Hexagon though I want to learn oneday)
that is how I fix mesh in Carrara or from Google Sketchup.

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Posted: 08 April 2013 06:04 PM   [ Ignore ]   [ # 4 ]
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Hexagon has one of the most comprehensive boolean tool sets of all the software I have used, but if it is used carelessly it will likely give poor results.
Just because the mesh may look ok after a cut or union etc does not mean that it is, or that your job of creating a good mesh is finished , so some things that might lead to a successful final result would be to check for duplicate points by merging, look for the number of points change in the properties panel when applying this command. Also intelligent use of the tessellation tools may be required.
As wendy says the triangulate ngons tool will also help but I find it is mostly good for flat faces and sometimes will cause problems in other software, particularly Daz studio.
Consider separating your object into multiple parts, it will certainly help.
It may be an idea to collapse any dynamic geometry.
A boolean approach may not be the suitable way to go.
Boolean work in Hexagon can produce excellent results with a little care and thought although experience in this case is valuable so try to take time and experiment.

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Posted: 08 April 2013 10:22 PM   [ Ignore ]   [ # 5 ]
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Sometimes using Dynamic Geometry can cause problems with exporting booleans.

Try collapsing the DG on the object you want to export.  I am not sure why that should make a difference but occassionally it does.

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Posted: 09 April 2013 02:19 PM   [ Ignore ]   [ # 6 ]
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cdordoni - 08 April 2013 10:22 PM

Sometimes using Dynamic Geometry can cause problems with exporting booleans.

Try collapsing the DG on the object you want to export.  I am not sure why that should make a difference but occassionally it does.

It’s a documented bug and yes that’s the correct solution.

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Posted: 09 April 2013 03:13 PM   [ Ignore ]   [ # 7 ]
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Very cool info thanks for that insight. Why is there a concenus out there that boolean’s are crap if it works well? I really would like to know if you have the time.

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Posted: 09 April 2013 06:37 PM   [ Ignore ]   [ # 8 ]
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Because Booleans often leave N-GONS, which are difficult to manage in UVs, texturing, importing into other applications.

They often leave duplicate points for which there is not a good way to deal with unless you have a utility or software like that in Lightwave, Maya etc. that can detect and fix them.

They are generally good for small things imo, but when modeling complex objects or organic objects - not so good.

Booleans sometimes will flip normals in the strangest places and you won’t know what happened until you try to UV and texture.

There are other things, but popcorn is calling my name - more like a scream actually. smile

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Posted: 09 April 2013 07:04 PM   [ Ignore ]   [ # 9 ]
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I have had good results using netfabb basic (free) to repair objects that become modeling dead ends. After I fix them in netfabb, I bring them back into Hexagon and do more booleans to them, until they break again.

I am only concerned with triangulated output however, so if you need quads using nefabb alone won’t help. Meshlab (also free) can convert tris to quads but unfortunately won’t convert ALL tris to quads.

The other issue is these utilities would only be useful on a non-UV mapped model. Once you export and repair them in one of these apps, you will lose any work you have done with UVs.

I have heard of some apps like atangeo balancer http://atangeo.com/ that can maintain UVs while doing repair or decimation on the geometry, but I don’t have any experience with those to mention how well they work.

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Posted: 09 April 2013 10:32 PM   [ Ignore ]   [ # 10 ]
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Booleans are basically shortcuts to something you could model, so where possible, rather model.  You can do the shortcut and spend time fixing, or take time in the first place to do it right:)

Used correctly, with matching edges etc., they do work well - one application in Hex where they work outstandingly well is in making complex polylines from simple shapes.

Thanks for the heads-up on netfab - must give that a try.

Interesting what you say about Meshlab converting tri’s to quads - it has several algorithms for doing this, but I have never gotten it to work - any chance of you giving a walk-through on how you do it?

Blender is the only free application I have found that can convert tris to quads efficiently, but will usually leave a few tris to fix manually.

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Posted: 10 April 2013 03:17 AM   [ Ignore ]   [ # 11 ]
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Thanks Design Acrobat, cdordoni and Roygee. I think i will stick to not using booleans at all. smile

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Posted: 10 April 2013 06:50 PM   [ Ignore ]   [ # 12 ]
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Oh, I’m not saying don’t use it at all - that would be limiting your modeling repertoire:)

This function certainly has its uses, but like any other function, just be aware of when it is best used, when not and the limitations.

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Posted: 10 April 2013 10:33 PM   [ Ignore ]   [ # 13 ]
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Roygee - 09 April 2013 10:32 PM

Interesting what you say about Meshlab converting tri’s to quads - it has several algorithms for doing this, but I have never gotten it to work - any chance of you giving a walk-through on how you do it?

Blender is the only free application I have found that can convert tris to quads efficiently, but will usually leave a few tris to fix manually.

Yeah, honestly I can’t remember which tris to quads algorithm worked the best since, I rarely used it. I would have to go back and try it again when I have some free time.

But Meshlab is just a pain to work with in general. I have an 8 year old version of Geomagic, which even though its still 32bit, is way better than Meshlab for most things. I was hoping to use Meshlab to replace it, since I have to run Geomagic in virtualized WinXP on my Win7 OS, but I can’t seem to get away from it. If I had an extra $3000, I would upgrade the Geomagic license.

But its good to hear Blender can accomplish this as well. I am going to have to learn that app since its useful in so many areas.

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Posted: 11 April 2013 04:11 AM   [ Ignore ]   [ # 14 ]
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Roygee - 10 April 2013 06:50 PM

Oh, I’m not saying don’t use it at all - that would be limiting your modeling repertoire:)

This function certainly has its uses, but like any other function, just be aware of when it is best used, when not and the limitations.

Yeah cheers I got that, thanks for making sure I did. smile

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Posted: 11 April 2013 01:48 PM   [ Ignore ]   [ # 15 ]
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Yes, Meshlab is seriously geeky - I have no clue what 90% of its functions are for, but it does do a really great polymesh reduction job.

I’m afraid that Blender is becoming pretty much inescapable for hobbyists who can’t justify the expense of high-end apps, so I’m learning it bit-by-bit.  Pretty much uphill, but getting there:)

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