Week 1 – Basic Compositing

In Week 1 we began by learning the basic controls and interface of Nuke. We started by placing some basic nodes to see what they did, and how the node system in Nuke works. We then did some basic keyframing to create a basic animation.

We then completed some tasks of merging different node trees together in order to get a “final” image, which you can see below.

Task 1

Task 2

Task 3

Week 2

In Week 2 we looked at Rotoscoping, which is one of the most common visual effects processes. Rotoscoping is the process of essentially “cutting out” something from an image, which then enables it to be placed on top of a different image. This can be done frame-by-frame or fairly automatically for simpler shots.

Rotoscoping is also one of the most common entry-level jobs in VFX, so it’s an extremely important skill to have. However, with the rise of “AI” based tools that vastly simplify the process of roto, this may not stay true for long.

balls

We started off by learning about the Roto node, this allows you to draw various different curves in order to cut things out.

original footage

After roto

 

After the balls are roto’d and premultiplied, they are then merged with a Constant background colour to allow you to easily see how well the rotoscoping process has went.

Building

For this piece of footage, we were tasked with rotoscoping some buildings, then using the Grade node to change their colours.

Original Footage

Roto’d and Colour Graded

The node graph shows use of the Grade node, the node comes with a “mask” arrow, allowing you to use the same roto for the colour grading.

Week 3 – Complex Roto

In week 3 we took a look at rotoscoping more complex shapes, like hands and full bodies. More complex shapes aren’t roto’d as a whole, they are split into smaller simpler shapes to give the artist more control over the roto.

Fingers

We started roto’ing this finger by breaking it down into its three main shapes, this allows you to move and rotate each part individually, allowing for much more natural movement of the roto.

You can organise the many roto’s in the settings of the roto node.

 

Motion blur can be added to the roto in the roto settings.

Node Graph

Week 4 – Keying

PREMULT

The premult node multiplies the RGB layers from the raw footage with the alpha layer that you create with the roto node. This works by multiplying the values of the alpha (0 for transparent, 1 for opaque) with the RGB values to create the transparency.

Keying vs roto

Roto is a time-consuming manual task, in comparison to Keying which can be done fairly automatically by the computer. Roto is used in situations where keying might fail to cut out an object, for example, if the footage was not filmed on a green/blue screen.

Chroma key

A chroma key uses the colour values of your image to create a matte. This works best with footage of people on a blue or green screen. The colour can be selected and will then be used to create the matte.

luma key

A luma key uses the brightness values in an image in order to create a matte. These work best on images with a high contrast between what you want to cut out, and the rest of the image. It works very well with removing the sky, as shown below.

keying in nuke – luma

keying in nuke – chroma

Week 5 – Colour Correcting & Grading

When combining different elements together one of the most important processes to getting it to “look right” is to colour correct your elements. You want all the elements in your scene to appear as if they were shot in the same place, with the same camera. To do this you have to adjust the colour values in your image accordingly.

Colour can also be used in the storytelling process, to evoke certain emotions or emulate a film stock. This is called Colour Grading.

Grade nodes

Week 6 – Tracking

One point tracK

two point track

Week 7 – Clean Up & Grain

Rotopaint node

The RotoPaint node allows you to paint onto your scene, this can be used to remove things like tracking markers. This can then be combined with the Tracker node to remove objects that move in your frame. Within the RotoPaint node there is a basic brush, a clone tool, and a reveal tool that can reveal a background image where you paint.Any brushes you make will appear in the node properties; it is important to set the “lifetime” of the paint to be “all frames” if you want to remove something from multiple frames of your scene. Here is the node setup for tracking the markers out of the scene. You can see a green line between the track and the paint, as the values of the track are being copied into the RotoPaint node.

Static patch

To remove the man from the image, we use a “FrameHold” node on a frame where he isn’t in the shot. We can then roto this section out and merge it with the main image, along with a track to match the slight shake of the camera.

Adding Grain

To match grain with our patch, we first denoise it, and then add a grain node. We can then adjust the sliders to individually match the grain in the red, green, and blue channels.

Assignment 1 – Technical

For Assignment 1 we were provided with some sample footage, shown below. Our task was to match this footage as closely as possible using the technical skills we have learned over the past 12 weeks.

Reference footage

my matching footage

Node Graph

Assignment 2 – Creative

Final Video

Breakdown

Node Graph