Normals are like tiny signposts on your 3D mesh in Blender, silently telling the software which way is “out” for shading and lighting purposes.
But sometimes, these normals get flipped, causing lighting issues and rendering headaches.
This article will guide you through showing, recalculating, and flipping normals in Blender to ensure your models render beautifully.
Showing Normals in Blender
The first step to take control of your normals is learning how to visualize them. Seeing the normal vectors on your mesh makes it much easier to identify issues and areas that need adjustment. Blender provides several options for displaying normals.
- First, switch to Edit Mode by pressing the Tab key or selecting “Edit Mode” from Mode menu in the top left corner of the 3D Viewport.
- In the Viewport Overlays menu (located in the top right corner of the 3D Viewport), check the “Normals” box under the “Mesh Display” section.
There are three icons you can click to display normals in different variations.
From left to right, the icons are “Display Vertex Normals”, “Display Split Normals”, and “Display Normals”.
Clicking any of them will show lines protruding from your mesh, representing the direction of the normals:
- Display Vertex Normals – Normals for each vertex
- Display Split Normals – Shows vertex normals that are split (where surface continuity breaks)
- Display Normals – Normal vectors for faces and surfaces (including Ngons etc.)
For most workflows, the “Display Normals” option is likely the easiest to use as it clearly shows the normal direction per face.
Additionally, you can adjust the length of the normal lines by using the slider control. Making the lines longer makes them more visible when zoomed out or working with larger meshes.
Alt+N Shortcut for Normals
In addition to the icons in the Viewport Overlays, Blender provides a handy keyboard shortcut – Alt+N – that cycles through different ways to control normals.
This menu provides several tools and options for modifying and working with normals, including:
- Flip: Inverts the direction of the selected normals.
- Recalculate Outside/Inside: Recalculates the normals to point outwards or inwards, respectively, based on the current mesh geometry.
- Set from Faces: Set custom normals from the selected faces once.
- Rotate: Rotate Split normals of the selected items.
- Point to target: Point selected custom normals to specified targets.
- Merge, Split, Average: Combines, separates, or averages normals of selected vertices.
- Copy/Paste Vector: Copies/Pastes normal to the internal clipboard.
- Smooth Vectors: Smooths the selected normals based on adjacent vertex normals.
- Reset Vectors: Resets internal clipboard and/or normal of selected element.
- Select/Set Face Strength: Set/Get strength of face (used in weighted normal modifier)
While this menu does not include the options on Overlays (Display normals), it provides powerful tools to manually inspect, adjust, and manipulate normals in precise ways for advanced mesh editing and correction workflows.
How to Recalculate Normals in Blender
In some cases, normals may become inverted or inconsistent, leading to unexpected shading and lighting issues. Consequently, recalculating normals can help resolve these problems. Here’s how to recalculate normals in Blender:
- In Edit Mode, select the faces or vertices you want to recalculate normals for (or press A to select all).
- Then, press Shift+N (or go to Mesh > Normals > Recalculate Outside).
- Alternatively, press Shift+Ctrl+N to Recalculate Inside.
Blender will recalculate the normals based on the current geometry, ensuring consistent shading and lighting.
How to Flip Normals in Blender
Sometimes, you may need to flip the direction of normals, especially when working with meshes imported from other software or when dealing with complex models. Flipping normals can help resolve issues like inverted shading or artifacts. Here’s how to flip normals in Blender:
- First, select the faces you want to flip normals for (or press A to select all).
- Next, press Alt+N > Flip (or go to Mesh > Normals > Flip).
Blender will then invert the direction of the normals for the selected faces or vertices, potentially resolving any issues caused by incorrect normal orientation.
Pro Tip: Blender also offers visual aids to identify flipped normals. In Edit Mode, enable “Face Orientation” under the “Mesh Display” section. Faces with flipped normals will appear dark, helping you pinpoint problem areas.
It’s important to note that while recalculating and flipping normals can solve many lighting and shading problems, they may also introduce new issues if not used correctly. Therefore, always double-check your mesh and lighting setup after modifying normals to ensure the desired results.
By understanding and effectively utilizing these normal-related tools in Blender, you’ll gain greater control over your 3D models appearance and achieve more realistic and visually appealing renderings.