Blender Tutorial: Subsurface Modeling

(It’s not really fair to call something with this many steps a “quick tip”.)

Blender is capable of some pretty impressive feats of “organic object” modeling, but to do organic modeling easily requires unlocking a popular tool among the 3D animator crowd known as “subdivision modeling”.  The idea behind subdivision modeling is that although the computer needs to draw many, many polygons to approximate a smooth surface, rarely are those smooth surfaces so mathematically complex that they can’t be more easily defined by a set of control points.

Many ways of doing this exist in the field of 3D modeling software, but one of the most intuitive, and one that Blender handles very well, is breaking the mesh down into smaller polygons and twisting them so that they reduce the sharpness of the corners of the original mesh.

If that seems like a bunch of jargon, that’s only because it is– let’s just do it and see what happens.

If you select the default cube, you should see this panel on the lower right:

There’s a long list of options available when you click the “Add Modifier” button, but we’re just going to use “subsurf”.

If you select the default cube and then select subsurf from the Add Modifier menu, you should see the following appear under the Modifiers tab, in what is called the “modifier stack”:

The cube, as you will see, has had each of its six faces subdivided into four smaller ones.  This represents one level of subdivision.  The “levels” item in the subsurf panel shows how many times this subdivision process will be performed by Blender while you’re editing it.  (For solid modeling purposes, we can ignore the “Render Levels” item, which is there so you can have Blender subdivide a model more thoroughly for rendering.)

For every level up we bump the Levels item, every face is subdivided into four new ones.  Below are cubes subdivided one, two, and three times:

The first has 24 faces, the second has 96 faces, and the last one has 384.  As you can see, going much higher than this will start to tax system resources at comparatively little benefit, especially if you select “set smooth” for these objects.

This is an interesting way to turn a cube into a sphere, but so what, right?  Well, the usefulness of this doesn’t become obvious unless we hit tab to switch to Edit mode:

As you can see, Blender’s edit mode is only using the original points.  For this reason, you can now distort the sphere into a bunch of other shapes just by moving the original vertices, which in a subdivided mesh are sometimes called control points.  What’s more, if you use some of the techniques from previous tutorials on this mesh, you can quickly produce some very organic-looking shapes with comparatively few operations:

This nifty teardrop shape was made with just two extrude operations and some scaling.  Pretty neat, huh?

Of course, if you use this very long, you’ll start to get frustrated by the way you have to pull verts through each other to get some effects, as well as how cluttered the view gets when you have a large, complex shape.  This is why the Blender developers have included the following option, although I may never know why they hid it so well.

See that little unassuming circle?  Click it.

NOW we’re talking!  With the “true” position of the original control points hidden, the view of the model is drastically simplified, but all the operations of extrusion, twisting, scaling and so on still can be applied to it.  The model we saw at the beginning of this tutorial was done in maybe three minutes of fiddling around!