[solved] What exactly is a "matcap" and how does it aid sculpting?

I have seen talk of the use of matcaps in ZBrush and Sculptris but I can’t find anything that explains what they are and how they enhance the sculpting process.

Does anyone have any examples of their use? Particularly in blender would be good?

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matcap stands for “material capture” – it is a complete material including lighting and reflections so you can add it to an object and not have any need for, well, lighting and reflections. It is most commonly used for sculpting, as it gives quick and useful feedback on how an objects shape is changing.

The key to using a matcap texture is that is is mapped to the object’s normals (which exist in relation to the camera), and your material is set to shadeless (because you don’t need lights to have any influence, as they are a part of the matcap texture):


So as the camera moves around the object, the reflections and highlights move around your object (as if the object were moving and not the camera). In other words, if your object were a sphere, no matter how you looked at it, it would look like the matcap sphere (reflections always in the same place, e.g.). But as your object takes non-spherical shapes, thus changing the normals, the material responds as if it were made of the complex material (in this example I’m using the zbrush jade matcap):


And this can be nice when sculpting. It also works with rendering, to an extent (good when you need to do a quick show-off-your-model render and don’t have time to set up any complex lights or materials).

Oh, and you need GLSL and textured shading enabled in your 3d view to see the matcap while working.

I’m feeling like this is a fairly muddled explanation; it’s late and I’ve had a long day. But matcaps are a lot of fun to play with, so go play.

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Awesome, thanks benu. That’s almost perfectly clear.

Is the matcap just an image then? Jpeg, PNG? Or is it a special file format?

Just an image. Often with an alpha channel to define the edges of the sphere.

Perfectly explained. Thanks benu.

Thanks Benu

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Richard

Good explanation!

Just one more question:

Is it possible to use a matcap “effect” in a Cycles or Eevee render? I know about HDRIs, but a matcap is differenrt, right? Because it’s unphysical (the world rotates with the camera), whereas an HDRI doesn’t rotate as you pan around the scene.

I haven’t tried these yet. What I tried was putting an object at the world origin and using a constraint to copy only the rotation from the camera to that object and then use object mapping in the world material to have the matcap image auto rotate to be in line with the camera. Set the texture node with the matcap image to “mirror ball”. The result is sort of similar to the matcap but not exactly.