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It's Good to Be Normal

Blender: Recalculate Normals – Simply Explained

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by Tian Ooi
Dec 10, 2018

Blender: Recalculate Normals – Simply Explained

Normals are a small but important part of your Blender model. They define what's "outside" and what's "inside" your model. So how do you recalculate normals that are facing the wrong way? Read on to learn more.

Blender Recalculate Normals What Are Normals?

Something's not right here...
Something's not right here... Source: Tian Ooi / All3DP

Ever wondered why your Blender model is sometimes plagued by random black voids?

The normal of a face describes the direction it’s pointing or facing. Usually, in a closed model, all normals should be facing outwards.

However, sometimes when manually manipulating edges and faces in Blender, the normals get flipped. It’s not the end of the world, but it does make your model look weird. And once you export the model, flipped normals can leave behind bad artifacts.

That’s why it’s best to fix these flipped normals. And the good news is, they’re super easy to recalculate.

Blender Recalculate Normals 1. Identify the Normals

Note how the normal lines are not facing outwards on the black faces.
Note how the normal lines are not facing outwards on the black faces. Source: Tian Ooi / All3DP

Usually it’s pretty easy to tell when your normals are out of whack. Try panning and orbiting around your model. If some of the faces are unnaturally black when they should be grey, their normals are probably flipped.

Blender also lets you see exactly where the normal on each face is:

  1. Make sure you’re in edit mode (bottom toolbar).
  2. Open up the properties panel by pressing ‘N’ or clicking little ‘+’ on the top right of the viewing screen.
  3. Under Mesh Display > Normals, you should see three little buttons along with a size slider.
  4. Click on the one highlighting the face of a box (3rd from left).

You should see little blue lines poking out of each face. If you don’t see a line sticking out on a face, that normal is flipped the wrong way.

Blender Recalculate Normals 2. Fix the Normals

Where to find the normal functions.
Where to find the normal functions. Source: Tian Ooi / All3DP

There are two main ways to fix flipped normals:

  1. Recalculate: In edit mode, press ‘A’ to select all. In the toolbox on the left of the 3D view, click Shading/UV > Shading > Normals > Recalculate (shortcut: Ctrl + Shift + ‘N’). This will auto-recalculate the selected normals so they all face outwards.
  2. Flip Direction: Sometimes the recalculate command won’t cut it. To manually flip a normal, first select your desired faces. Instead of “Recalculate”, press “Flip Direction” (shortcut: Ctrl + ‘N’).

For Blender 2.8 users, the command has changed a little bit. Go to Mesh > Normals > Recalculate Outside (shortcut: Shift + ‘N’) to recalculate the normals.

Blender Recalculate Normals 3. Success!

The model with all the normals the right way.
The model with all the normals the right way. Source: Tian Ooi / All3DP

Your normals should all be facing outwards now. Save your work and go about your merry way.

License: The text of "Blender: Recalculate Normals – Simply Explained" by All3DP is licensed under a Creative Commons Attribution 4.0 International License.

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