I've made a second attempt at creating realistic Potato-Chips.

https://vimeo.com/76864119 [vimeo.com]

The mayor innovation in this version is my layered noise .otl, that works in the SHOP and SOP context joined by a preview node for easy previewing and isolating individual layers for tweaking. It allows one to layer 3 different layers of noise, have float and vector outputs, apply various operations to combine the layers and offset the noise patterns by an id input.
I've introduced the idea of a float id attribute, where the rounded number and the fraction can be handled differently. For instance, the whole number can be constant per object or piece, where the float value can be different on a per point basis with only minor differences, allowing for a wide range of artistic control.

I'm using different sets of layered noise for channels like diffuse, spec, displacement and refraction. Part of the trick is to have some sets that share similar patterns. For instance the larger displacement pattern (single layer) is also used to drive the base layer of the diffuse. To get the snowy peaks idea, but then topped up with two different layers to make it look more natural.
I never used the exact same patterns to drive different channels of the shader, people are really good at spotting patterns.

Another feature of the potato-chips shader is that it takes a ‘edge’ attribute, basically an attribute that has a 0-1 value from the center to the edge. This allows to scale down displacements that are closer to the edge, add burned edges and that sort of stuff.

I found that per piece random slight color offsets help to sell the shot as well. It makes it easier to believe they are real.

Apart from that it was a tremendous amount of testing, I found it so difficult to get the right look. In the process I've created a ton of pringles, those are easy ;-).

The pieces don't feature the ‘popped bell’ things, because

A I couldn't get it right on a procedural basis (probably need to create hero pieces for that)
B. This is aimed at clients in the television commercial business and I don't think Lays wants any of these things in its commercials.

You can find a detailed article (though aimed on potential clients) on my website: www.nicknimble.com/index.php?option=com_content&view=article&id=129%3Acgi-potato-chips-attempt-2&catid=40%3Atechnical-achievements&Itemid=55&lang=en [nicknimble.com]

Very nice. The grainy texture and gentle light diffusion help make those tumbling, seasoned chips look quite appetizing.

It might also be neat to see some crumbling and hint of oily residue along the side of the dish.

Now I'm hungry !

It's really cool