Category Archives: Vfx

Nuke Ramped Defocus

A quick group for better defocus

If I have an image in nuke that I want to control the falloff of the depth of field, ordinarily I would pump a ramp into the mask input of defocus. However, this would only work if I want my defocus to start at 0 and move to some value. If, however, I want the smallest amount of defocus to be something other than 0, say 2, I can’t achieve this effect with a good result, even if I adjust the start value of my mask input (instead of ramping from 0-1, say .2-1). If I input this ramp into the mask input on a defocus, this is the result:

maskedDefocus

Instead of moving from a 2 defocus to a 10 defocus, instead I get the original un-blurred result, with the 10 defocus merged on top of it at 20%, creating a halo.

With a few merges and two defocuses instead, I can get a much better result:

rampedDefocus

So I grouped this little setup and posted it here. Simply add a gradient map into the ramp input, 0-1, and set your minimum blur and maximum blur values, and you’ll get a much smoother result.

Download:

rampedDefocus
tested on Nuke 9.0v4

Nuke VHS Noise Group

mograph in Nuke?!

vhs063

I’ve recently had to create (and re-use) a customizable VHS tracking-error style effect in Nuke, and have collected the node group in the attached file. It’s mostly controlled by some nobs on the “MASTER” node, though there are some other tweakable elements here. Unfortunately there’s no documentation so you’ll have to play around with it, but I’ve been getting good results from it.

Download:

vhsNoise
tested on Nuke 8.0v1

Nuke multiGrad

an advanced 4-point gradient gizmo for rotoscoping

***updated 3/9/2015

I’ll be the first to admit that I’m no expert on rotoscoping, but in my experience one of the first tools I look for is a multi-gradient – something that I can use to paint out large sections of the image, and then add detail to. So I was surprised that, besides this shake-like 4-point gradient there wasn’t anything in Nuke that was what I wanted. The shake gradient is nice, but I was really looking for one that would allow me to move the points around in space, and would interpolate colors around the points as well as in between. With some patience and a lot of math (point-slope anyone?) I created a gizmo that will do just that. Below you can see the results on a racecar:

Of course, it’s not perfect, and there would need to be fine tuning around the edges, but all the rotoing in that image was done just with this tool. The user pipes in the source image to “Source” and a mask to “matte”, and the gizmo will comp it onto the source automatically, preserving the source alpha (the user can turn this feature off under the “Matte” tab. It also includes python scripting that will automatically grab the color of the source at the points, which makes painting out areas really quick and easy.

Control Panel

Because of the math involved, points 1 & 2 must be at the top, and 3 & 4 at the bottom, or it will start to act screwy. If it needs to rotate, you’re better off translating the whole result.

Download:

4pointgradient.txt
tested on Nuke 9.0v4

Technodolly Focus, Z-Depth, and Lens Distortion

being one of the only google search results on the technodolly
techno_dolly

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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