Why does this happend with Shell?

[cris.allemant]

I was following this tutorial but why do I get these random distortions on the faces when I use shell???.

https://youtu.be/sXNK2ijHReY?t=229 

Someone Please help!

[10DSpace · Accepted solution]

@cris.allemant 

Those artifacts look like just a smoothing group issue.  To verify this, put an Edit poly modifier on top of the Shell modifier and in polygon subobject mode go to the Polygon Smoothing Groups section of the Edit Poly rollout and with the polygons selected, click on "Clear all".  

In terms of why it is happening, 2 very common ways you can produce smoothing artifacts while modeling are (1) unintentionally moving a vertex out of the plane of the other vertices in the polygon (2) or unintentionally creating  duplicate vertices or edges.  Generally, selecting vertices and welding with a low threshold will fix (2).  

[cris.allemant]

Thank you so much for taking the time to reply!, I did the ''clear all'' fix but what I'm wondering is why I have to do this.

The guy in the youtube tutorial didn't have to do it and I took the exact same steps. is quite annoying.

But either way, I appreciate the reply!

[10DSpace]

@cris.allemant 

I did the ''clear all'' fix but what I'm wondering is why I have to do this.

In the 2nd paragraph of my above response, I offer 2 possible reasons why you had to do this, so read the paragraph again.   You can test these yourself by examining your mesh below the shell modifier for evidence of either (1) or (2).   It has nothing to do with the shell modifier in my experience, but rather the mesh that you are feeding into the shell modifier.   See if there are duplicate vertices or if one of the vertices of the polygons are out of the plane of the others in these polygons.    If you are not sure how to do this, then post your max file here and I will take a look and try to show you. 

[cris.allemant]

Wow that'd be extremely helpful!!

[10DSpace]

@cris.allemant 

OK here is the issue in your case.  When you cut into the wall for your window, Max automatically assigned a different Smoothing group (SG = 2) to the middle 2 polygons  (the ones above and below the window compared to the wall polygons on either side  (SG=3).   After all, max doesn't know what you have in mind for your model, so since you started changing the geometry it assigned a different smoothing group to the changed geometry.   So another simple fix is to just deselect smoothing group 2 for the middle 2 polygons and then select smoothing group 3 for them.  This tells max to keep the surface smooth across all 4 of these polygons. 

I notice that you are using a student version of max, so I recommend that you take this opportunity to learn a bit more about smoothing groups as it is a very powerful tool for controlling the look of your models.  There are some very good tutorials by Arrimus 3D here:  

https://www.google.com/search?q=3ds+max+smoothing+groups+tutorial+arrimus&oq=3ds+max+smoothing+group...

The last point I will make is that the original modeling tutorial you were following may not have shown all of the steps.  Sometimes online videos are edited and steps are inadvertently omitted. So don't be put off by the fact that the author of the original video you were following didn't seem to have a smoothing group issue.  The important point is that you now know how to control this.

Hope this helps. 

[domo.spaji]

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@10DSpace wrote:

 When you cut into the wall for your window, Max automatically assigned a different Smoothing group...

 No, all that Max will automatically do with smoothing is not assign any smoothing group to newly created polys (not case here).

@cris.allemant 

Very bad sources for learning.

Why don't you start with official help docs and tutorials?

[10DSpace]

@domo.spaji 

Very bad sources for learning

Why exactly do you say these are very bad sources of learning?   It would be more constructive to state why they fall short in your opinion. 

[domo.spaji]

I'm pushing official sources in front of public ones - always!

Will not justify that.

Max had very good help files, not keeping step last years but still...

Also, not considering this forum as official source regardless of name or owner.