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I read that normally, Normals should be facing outward; that is, the normals pointing out of the object. I have a character modeled and when I use Ctrl + N to reclaculate normals, all normals points inward. I would've thought pressing Ctrl + N would make all the normals point outward.

If I use Shift + Ctrl + N or check the Inside tickbox, then it points outwards. Isn't that the reverse of what should be happening?

And how do I decide if normals should be outside/inside anyway? What things should I consider?

EDIT

The blend file

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    $\begingroup$ I don't know why it decided to put the normals inside, but anyway yes it's better to have them outside, i.e. on the visible faces, so I guess let them at it is now $\endgroup$
    – moonboots
    Commented Jul 11, 2019 at 6:32
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    $\begingroup$ Yes normals should be facing outward. My guess is your mesh has some (unnoticeable) topological errors causing blender to mistakenly count the inner surface as the outside. $\endgroup$
    – sacrish
    Commented Jul 11, 2019 at 10:58

2 Answers 2

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It's important to have the normal pointing outward of your model, otherwise back face might be visible at render time and give bad visual effect.

The reason blender still allow normal to be calculated inside is for specific use case like rendering a room from the inside.

However, when there is something wrong with a model, blender might have a bad time computing the normal and you might have to flip them manually if some if them are wrong.

I can help you more if you post screenshots or share your blend file.

Update new that I have seen the blend file :

You faces were indeed inward, you can see that by going in edit mode and activating the face orientation visualization tool ( red is the back of the face, blue is the front, so red should never be in render sight ) :

face orientation tool

The reason Blender is having trouble computing the orientation is because your model is "open" at the hands, neck and bottom, that kind of hole should not appear in your final model. If you don't want to add more geometry I would suggest using the solidify modifier, it will simply add some thickness to the planes and red faces won't appear anymore.

enter image description here

Or if you want simply want to have the faces in the correct orientation as a quick fix just select every faces and perform a flip normals operation.

flip normal

Face correctly oriented

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    $\begingroup$ Thanks, I added the link for the blend file in the question above. $\endgroup$
    – g_b
    Commented Jul 11, 2019 at 12:49
  • $\begingroup$ Okay, I see what's happening i will update my answer shortly. Your faces were indeed inward, flipping all the normal will fix everything. $\endgroup$ Commented Jul 11, 2019 at 13:57
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    $\begingroup$ Thanks a lot, really appreciate it! $\endgroup$
    – g_b
    Commented Jul 11, 2019 at 22:38
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In the Overlay you can always check 'Face Orientation'. Blue = outside, Red = inside

enter image description here

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