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# 1 02-12-2013 , 05:36 PM

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Join Date: Dec 2013
Posts: 22

#### Crazy black faces

Good Day everyone!

I'm not a complete noob to 3D/Maya, but now I'm stuck and just cannot figure out what's going on. It's a face modeling which I would like to print out later.
Right now the faces are going crazy, let me explain.

I try to fix this hole (border selected, shown in orange) - Mesh -> Fill Hole does not work. Append to Polygon also does not work (cannot select the edge), also I have no experience with this tool, because normally I do it as follows and it worked well up to now:

Use Interactive Split Tool to put vertices on the single edge (left, red dot shows vertex-position) where I want the vertices from the edges to the hole's right side to merge to. I just click once and press enter to put a single vertex there.

I do this a second time.

I then select those 3 edges on the hole's right side and pull them out (note the circle-selector set to "world" if I am not mistaken). Oh, what's that, a black face? This normally does not happen, but alright, let's just flip the Normal around (normals -> reverse) on this face.

Looks alright now.

Merge the vertices accordingly (merge to target vertex), showing only step 1:

Moving one of the edges up and down, it shows strange black shapes, I guess because the face is not planar, but I do not know.

Because I had some problems with black faces trying around with this model and am unsure about whether there are double edges, vertices, faces because I did a lot of the "extrude edge to create new face"-method shown above, I want Maya to do a cleanup.

Afterwards the polys start flickering black all over the place.

Deleting some of them it shows: there are now double faces underneath (or rather in the same coordinates) but with flipped normals (because they show black).
Deleting the 3 freshly created faces just makes a hole, there are no doubles.

Another face has its twin there, but it has the same normal (edges in orange; face was deleted, same face
underneath).

Also Booleans do not work, which might account for "there's a problem indeed".

Can someone help? Why are these issues appearing and is there a better method for creating new quad-faces?

Kind regards,
borlag

Last edited by borlag; 02-12-2013 at 05:38 PM. Reason: wrong info

# 2 02-12-2013 , 08:52 PM

Lifetime Member
Join Date: Feb 2013
Location: Down Under
Posts: 245
Can you upload your scene file so I can have a look and a bit of a play with it?

Cheers, the Yeti.

# 3 02-12-2013 , 09:18 PM

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Join Date: Dec 2013
Posts: 22
MrYeti, I have sent you a private message including the scene file.
If others are interested in having a look, please leave a message.

# 4 02-12-2013 , 11:16 PM

Lead Modeler - Framestore
Join Date: Feb 2003
Location: UK
Posts: 6,287
You have faces with more than 4 sides. and also bi planar surfaces. You basically need to work a bit slower and sensibly and possibly slower. Check your 'keep faces together is checked. Also if you have a hole, just use fill hole command then just add the extra edges to finish it off.....

Jay

# 5 03-12-2013 , 07:49 PM

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Join Date: Dec 2013
Posts: 22
Can these problems really account to just some faces having more than 4 sides? The issue of doubled faces after cleanup also applies to all faces with just 4 sides. Before cleanup working with these non-quad-faces is fine. Or are non-quad-faces a total no go? What about Tris?

For face-side counting: if I put 2 more vertices on one edge like in my example above, does that mean that face counts as having 6 sides? Because it would have 6 different edges (3 standard edges, 1 cut in 3).

Keep faces together is on,
Fill Hole, as I said, does not work on that hole at least.

# 6 06-12-2013 , 08:21 PM

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Join Date: Dec 2013
Posts: 22
Maybe someone will have an use for him/herself in reading what I have learned:

- an n-gon is a face with more than 4 sides. sides means edges in this case, so even if one "side" of a face is perfectly straight, but split into 2 edges by a vertex somewhere along in it, it counts for 2, thereby making the face an n-gon (if all other sides are not split).
So, if I am not wrong you can only rid your mesh of ngons if you split all neighboring polygons of that specific ring/row as well. So, as a rule of thumb: If there is a vertex on an edge, both faces sharing that edge need to be split.

- my specific problem seems to have stemmed from accidents while extruding edges/faces; thank you MrYeti for pointing this out. These double faces also made it impossible to use the "fill hole" command on the hole shown in the images in my first post; after deleting the doubles it could be used.

- Thank you, Jay, for reminding me of working slowly, it really is of value to think more about what to do than just click along. Planning seems to pay off.

Questions still open:

-Poly with 3 sides are good/allowed?

# 7 06-12-2013 , 10:37 PM

Lead Modeler - Framestore
Join Date: Feb 2003
Location: UK
Posts: 6,287
Tris are okay but just 'tri' not to if you can help it. unless you are making a game model.

Visit the topology thread...https://simplymaya.com/forum/showthread.php?t=24483

it was intially for use with characters but a mesh is a mesh is a mesh at the end of the day

Jay

# 8 04-02-2014 , 12:54 PM

Registered User
Join Date: Feb 2014
Posts: 7
did u just check the two side lighting off in maya i always prefer to turn off two side lighting off when modeling
also try asign a blin shader so that u can judge ur mesh easily

# 9 04-02-2014 , 08:11 PM

Technical Director
Join Date: Feb 2004
Posts: 2,988

did u just check the two side lighting off in maya i always prefer to turn off two side lighting off when modeling

That's not the issue; the issue is incorrect geometry.

Imagination is more important than knowledge.

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