Category Archives: Houdini

Houdini CloudMaker OTL


I’ve been working on some cloud-related projects, and I needed a streamlined way to make many different clouds – with art-directed shapes – quickly and simply. I’ve come up with an OTL that takes rough input geometry and then builds a wispy, fractal-y volume for rendering.

The asset is implemented in Volume VOPs, using simple noise equations to extrapolate cloud-like edges. It creates an intermediate geometry out of metaballs, then creates a volume and adds noise. With this, you can quickly and easily create simple cloud shapes and convert them into high-quality clouds for rendering.


cloudMaker OTL
requires houdini 12.5 or higher

Houdini Animation Curves otl


I’ve recently been working on an idea that requires me to do separate luminance values in an image into x discreet “steps”, such as 0-12. However I don’t want to do the distribution linearly (read: equally distributed), I need to account for the fact that luminance is non-linear.

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Technodolly Focus, Z-Depth, and Lens Distortion


Any comp lives or dies on subtle qualities of a scene – color, depth of field, lens distortion, etc etc. Solving lens distortion with nuke is pretty easy once you understand the process (and immensely easy if you prepare ahead of time!); without a good lens distortion solve you’ll never get a convincing composite. Depth of field is easier to do a guess-and-check method, but of course we’d much rather get an accurate result. We’ll discuss both, but first a quick overview of the technodolly itself.

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Luminance Curves


Often in compositing, I will need to take one set of values and convert it to a different set of values. Say I have a linear image, with luminance values in a range from 0 – 4.589:

Input: Output:
0 0
4.589 1
If I want to do some fancy operation on that image based on it’s luminance, I’ll probably want to convert that range to 0-1, so it’s easier to work with. The easiest and most straight-forward type of conversion is a linear one, of course, where we simply divide all the luminance values by the largest value, giving us a range of values between 0 and 1:

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