I know this has diverged a bit from the original "waxy leaf surface shader" topic, but I think it's best to continue posting to this thread rather than a new one.

My main interest is getting a nice leaf shader that I can use on all those old plant and tree models (and XFrog OBJs) that use one-sided transmapped squares for leaves.  This is a quick summary of what I think I've learnt over the past day:

• bagginsbill's scatter-based leaf shader doesn't seem to have a noticeable effect when applied to the leaves of the ivy in my render. Two likely reasons: (1) the scatter node requires a mesh with volume to work properly, and this ivy is one-sided transmapped squares; (2) my particular scene and lighting isn't a very good test.

• leaf translucence (assuming infinite lights with ray-traced shadows) is automatically handled by the basic diffuse channel, EXCEPT if the leaves are back-lit and viewed from the front.

• the translucence node of the Poser surface can be used to add leaf translucence (assuming infinite lights with ray-traced shadows) for back-lit front-viewed leaves.

• the leaf translucence effect seems to require a basic Poser light with ray-traced shadows (I've only tried an infinite light so far). bagginsbill notes that it doesn't work with IDL. I've only tested with an infinite, so not sure about point/spot/diffuse IBL. It doesn't seem to work with depth-mapped shadows (I read somewhere that depth-mapped shadows are required for the fastscatter node, so that might be an option?)

And here are a couple of observations on problems with the standard leaf shaders - some might be easy to improve in the shader:

• most plants use a single leaf texture image (maybe two), so every leaf looks the same. Something in the shader to add a bit of randomness might be good?

• the bump image for most leaves is usually just a greyscale version of the texture image, so the veins appear raised, which is (usually) correct for the underside of a leaf, but wrong for the upper surface. Using a math subtract node, or GIMPing the image can correct this.

• the transmapped squares used for leaves are usually flat (i.e. the four vertices are coplanar). It may be possible to use displacement to warp each leaf slightly?

• the underside of a leaf is often very different from the upper surface. You really need a 3D mesh for this. But just maybe, the exploitable difference between front-lit and back-lit materials thread that bagginsbill linked to... ?

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The 3Dcheapskate* occasionally posts sensible stuff. Usually by accident.
And it usually uses Poser 11, with units set to inches. Except when it's using Poser 6 or PP2014, or when its units are set to PNU.

*also available in ShareCG, DAZ, and HiveWire3D flavours (the DeviantArt and CGBytes flavour have been discontinued).