This is a short video for Blender beginners to clarify three tools related to geometry edges. These are Mean Crease, Bevel Weight, and Mark Sharp.
Video Transcript
Hello everyone! This is a short video for Blender beginners to clarify three tools related to geometry edges. These are Mean Crease, Bevel Weight, and Mark Sharp. The first two are values, while the third is an operator.
On screen, I'm showing three identical objects that have been set to Smooth shading, which has significant issues due to faces with very steep angles, particularly between the bases of the cylinders and their side surfaces.
You may already know that these shading issues can be resolved using the Auto Smooth tool, which in Blender 4.5 is the Smooth By Angle modifier. This modifier simply applies the Mark Sharp operator automatically.
It’s really the same tool, and I'm now applying it manually to a few edges. These edges will appear highlighted in cyan in Edit Mode. Compared to using Auto Smooth, applying Mark Sharp manually allows for more fine-tuned control over which edges are affected.
This tool modifies the Normal information of the faces, so it affects their shading, but it can also be used with other modifiers. For example, the Edge Split modifier will physically separate the geometry along edges marked as Sharp as if they were seam lines.
Mark Sharp is therefore related to shading. Mean Crease and Bevel Weight are values that influence the behavior of the Subdivision Surface and Bevel modifiers, respectively. We can set these values for selected edges in the Transform panel of the 3D Viewport.
The Subdivision Surface modifier adds subdivisions to the geometry and then smooths the result, which tends to shrink the geometry. However, if we want certain parts, such as the cylinder base edges, to remain closer to their original shape and position, we can adjust their Mean Crease values.
The final shading will still look bad, but that’s because this value affects Subdivision Surface, not shading. For shading, we need to use Mark Sharp or other tools.
This is one of the reasons you’ll often see people use supporting loops with Subdivision Surface: they keep the original edges in place and improve shading at the same time. However, the downside is a significant increase in the number of vertices, edges, and faces in the final geometry. So it’s better to use Crease and Sharp when possible.
Finally, the Bevel modifier allows us to smooth edges by subdividing them one or more times, which also has a good effect on shading. The problem is that the modifier may be applied to geometry we don’t want to affect. For example, let's say we don’t want to bevel the bottom bases of the two cylinders.
The Mean Bevel Weight parameter in the Edge Data section of the 3D Viewport panel seems like it might help. However, when we modify its values, nothing happens.
That’s because we first need to change the Limit Method of the Bevel modifier from Angle to Weight. Once that’s done, we can go back to Mean Bevel Weight and set it to 1 where we want to see the modifier’s effects, 0 where we don’t, and intermediate values for proportional results.
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