Anatomy of a Leaf

Walking through the ideas behind making a leaf.

The goal is to build a leaf resembling that of a common houseplant. Looking at a plant in the real world we notice two things: first, the leaf is not uniformly green, as it possesses veins of color, and second, the leaf has a "waxy" look which we'll try to simulate by modulating the specular channel. 

The following is how we build the leaf. The leaf was created entirely through the use of procedurals, no image maps were needed to create the leaf. Now we'll pick apart the different layers of this leaf shader. The leaf is built up slowly, one layer at a time. None of the layers is convincing by itself, but put all together, the leaf looks like a leaf.

Layer 1

Layer one is a simple green Blinn shading model, attached to the leaf. The geometry of the leaf consists of a deformed NURBS sphere.

Layer 2

Teal spots, created with a Worley float, are added to the second layer, a new Blinn layer. The Worley modifies this layer's opacity.

Layer 3

Subtle brown stripes, created with a Color Ramp, cross the leaf on layer number three. The Color Ramp modifies the opacity of the third Blinn layer.

Layer 4

Louder stripes, created with another color ramp, run down the leaf. An ST manifold connected to the ramp and the S offset was adjusted to get the ramp to line up with the leaf edges. This ramp modifies the opacity of a fourth Blinn layer.

Back to Layer 1

Finally, a Turbulence float is connected to the specular value, Ks, of the first layer. 
And presto . . . the leaf is complete.

The call graph.

1) Base layer.
2) Spots.
3) Brown stripes.
4) Green stripes.
a) This ST manifold feeds two float nodes.
The Palette

This is the reason why the call graph is so mighty.


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