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I'm trying to grasp why some of these faces would be labeled as inner faces despite not actually being so. As I'm learning on my own, best practices for creating meshes are something I'm still learning, but I still hope to be able to convert this into a usable mesh for 3d printing. Any advice on why this would be so would be greatly appreciated.

enter image description here

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  • $\begingroup$ Can you share your .blend file? $\endgroup$
    – Jakemoyo
    Sep 20, 2022 at 20:38
  • $\begingroup$ I added it to the post @Jakemoyo $\endgroup$ Sep 21, 2022 at 0:00

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I've downloaded the .blend file you provided and had a look at the model.

The problem you are having with your normals is due to some issues with the geometry. Most obvious are some holes in the mesh. For example around the collar:

enter image description here

You may know this already, but you can check which normals are flipped by enabling this setting in the Overlay menu (blue is an outward facing normal, red is an inward facing normal):

enter image description here

Here I've highlighted some problematic areas that are likely affecting your normals:

enter image description here

You also have quite a few triangles throughout your mesh. Although these are unlikely to impact your normals, you may have issues when trying to animate/texture your model. Triangluar faces may also have an impact on any 3D prints, but I couldn't say for certain.

Generally speaking however, good topology requires that all of your faces are 4-sides faces (no triangles, no polygons with more than 4 sides). If you are trying to make a high quality model that you intend to use in future projects, it's very good practice to stick to quad faces only.

Here is a YouTube video discussing rules for good topology; there are plenty of others available online: https://www.youtube.com/watch?v=jEZUItEz6DA

As I couldn't post this answer during BSE maintenance, I had a go at cleaning up your model.

Here are some other things I noticed in the process:

  • You have some internal faces (faces that are inside your model). These too can cause issues with your normals. As you will see further down, internal faces are one of the biggest problems you currently have with this model:

enter image description here

enter image description here

As a general rule, your model should only include faces that can actually be seen from outside the model. Internal faces that will never be seen have a series of negative effects, including impacting your normals, messing up animations, slowing down render times, etc.

  • This area, apart from having some triangles, also has some disconnected faces, and some overlapping faces. These are also causing issues with your normals:

enter image description here

  • This area has some general messy geometry that needs to be cleaned up:

enter image description here

  • Same on the nose:

enter image description here

  • The internal geometry of your arm pits has holes. These will require significant work to fix, which I didn't really feel like doing.

(Image taken from inside the model):

enter image description here

  • The internal geometry of your shirt/tie/arms is also a significant issue. As mentioned above, internal faces (that cannot be seen from outside the model), can cause significant problems, and your shirt has a LOT of them (all the blue faces in the below image):

(Image taken from inside the model):

enter image description here

If I delete some of these internal faces, you can see the correct (outside) faces behind (in red, as we are looking at the back of the outside faces from inside the model):

enter image description here

Again, this will require significant work to correct which I don't really have time for.

I would recommend removing all of these internal faces, leaving only the outside faces of your model. Unfortunately, some of the internal faces of the shirt/tie etc. are connected to the outside faces of the head:

enter image description here

After deleting the internal faces, you will need to connect the external faces of the head to the external faces of the shirt/tie/arms etc.

Here is an image with the mirror modifier disabled that does a better job of showing the problematic, internal faces that need to be deleted:

enter image description here

enter image description here

I've provided an updated file here: https://www.dropbox.com/s/nc6uaezcen8etns/pug%20assassin%20with%20a%20suit%20and%20shadesrev3%20-%20Copy.blend?dl=0

I've corrected a lot of the problems with your normals, and cleaned up some of the triangles (although many still remain). It's a start, but you will still have plenty of work to do to correct the remainder of the model, particularly the internal faces on the inside of the shirt, and possibly also the arms etc.

Instead of attempting to manually find and remove all of the internal faces, you may find the following approach is more effective:

  • Start by selecting some of faces that you want to keep (external facing, blue faces).
  • Separate these faces into a separate object by pressing P
  • Select some more faces that you want to keep and press P. Repeat the process
  • You will end up with a bunch of models comprising the faces you want to keep, and your original object should contain only internal faces that you want to delete.
  • Delete the original object.
  • Select the new objects and join them into a single mesh using CTRL+J
  • In edit mode, use A (Select All) > M to merge vertices by distance (this will take care of any overlapping vertices).
  • You should also use A (Select All) > Shift+N to recalculate normals one more time.

You will still need to do some modelling to fill in some holes, and I would once again recommend trying to remodel some areas to quads (no triangles, no polygons with more than 4 sides). But the above steps should leave you with a much easier place to start.

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  • $\begingroup$ I spent some time trying to clean some things up before posting on here and while quite clearly missing many, I'm glad to hear all the input. After spending a good portion of the day deleting and replacing faces on the head and around the tie area I was feeling pretty discouraged. Some of the under the arm deformation came from having an actual body model, making the coat around it, playing around with snapping, deciding to delete the body. Thank you very much for looking into it! $\endgroup$ Sep 21, 2022 at 5:09
  • $\begingroup$ You're welcome :) Don't get discouraged, you're facing the same problems we all did at the start! If you wouldn't mind, could you please accept my answer? An upvote would also be very much appreciated. $\endgroup$
    – SlickRed
    Sep 21, 2022 at 8:28
  • $\begingroup$ I had a final thought on how to handle the internal faces. I've added a note to the bottom of my answer. $\endgroup$
    – SlickRed
    Sep 21, 2022 at 11:18

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