Category: Nuke

This week we learned about the VFX workflow, such as Tech check and Softwares Project Management.

The teacher analysed last week’s assignment and the feedback, which made me realise that compositing requires not only interesting combinations but also a clear theme and style and that it is essential to be aware of the coordination of the different elements. So I re-imagined my hot air balloon project, and I wanted to put it in a playground.

Rotopaint(pressing P on Node Graph)

For clean up and clone

When drawing your shapes, you can:

1. Click in the Viewer to place points. You can drag while clicking to pull out Bezier handles or adjust B-Spline tension.
2. Ctrl/Cmd+drag to sketch the shape freely.
3. Click the first point or press Return to close the shape. To leave the shape open, press Esc.
4. Ctrl/Cmd+Alt+click to add points to an existing shape.
5. Select a point and press Z to increase the smoothness of the point.
6. Select the point and press Shift+Z to cusp the point.
7. Select the point and press Delete to delete a point.
8. Beziers: Shift+drag on a tangent handle to snap the opposite handle to the same length. Ctrl/Cmd+drag on a tangent handle to move it independently of its opposite handle.
9. B-Splines: Ctrl/Cmd+Alt+drag on a point to adjust its tension.

Erode (filter)

Filters input pixels relative to the size control, and is particularly useful with mattes. Negative values cause brighter areas to expand into darker areas and positive values cause darker areas to expand into lighter areas. Use the filter dropdown to control the erode computation speed (box) versus quality (gaussian).

Erode (filter) is similar to Erode (fast), but can be computationally more expensive because you can select the filter type to improve the erode quality.

FrameHold

Lets you either:

• pick one frame and use that frame at every frame of the input clip, or • use every certain number of frames of the input clip (for example, every fifth frame).

Grain

The Grain node lets you add synthetic grain (rather than grain derived from actual film stock) to an image. This helps you ensure that all of the elements in your composite, including those which were digitally generated, look like they were shot on the same film stock.

The presets dropdown menu includes predefined types of grain, such as Kodak 5248 and Kodak 5218. These are the correct size for 2K scans.

You can also adjust the Grain node’s controls to match a sample piece of grain:

1. Find a sample with a rather constant background.
2. Blur the sample to remove the grain.
3. Connect the blurred sample to the Grain node’s input.
4. In the Viewer, wipe between the Grain node and the original sample image, and adjust the Grain node’s controls to match the grain. It helps to view and match each of the red, green, and blue channels separately.

Shuffle

Shuffle lets you:

1. rearrange up to 8 channels from a single image (B input). For example, you can use it to swap rgba. red for rgba. green, and vice versa,
2. rearrange channels between two separate nodes (A and B input), like a foreground and background branch.
3. replace a channel with black (removing the alpha channel, for example) or with white (making the alpha solid, for example),
4. create new channels.

PlanarTracker

PlanarTracker is a powerful tool for tracking surfaces that lie on a plane in your source footage. Planar tracking is often better than tracking individual points (with the Tracker node for instance) as it takes a great deal more information into account and gives you a more accurate result. A rigid surface, like a wall or a side of an object, are good planes to track. You can use your tracking results to replace the tracked plane with another image for instance. You can define the region to track by creating and animating roto shapes.

Conerpin 2D

The CornerPin2D node is designed to map the four corners of an image sequence to or from positions derived from tracking data. In practice, this node lets you replace any four-cornered feature with another image sequence. You can use it to place an image in an on-screen television, for example.

Before using this node, you should use the Tracker node to generate four tracks, one per corner, on the feature requiring replacement.

Convolve

G

Color：Logarithmic and Line

Colorcorrect(pressing C on Node Graph)

The ColorCorrect node is used to make quick adjustments to contrast, gamma, gain, and offset. You can apply these to a clip’s master (entire tonal range), shadows, midtones, or highlights.

You can control the range of the image that is considered to be in the shadows, midtones, and highlights using the lookup curves on the Ranges tab. However, do not adjust the midtone curve – midtones are always equal to 1 minus the other two curves.

OCIOColorSpace

Much like the standard ColorSpace node, you can use the OCIOColorSpace node for converting an image sequence from one colorspace to another. The OCIOColorSpace node is based on the OpenColorIO library.

Blur:

Erode blur

Similar to Erode (filter) , but smoother, input pixels are filtered relative to the size  control. Negative values cause brighter areas to expand into darker areas and positive values cause darker areas to expand into lighter areas – particularly useful with mattes. Additionally, you can add blur to the input using the blur  and quality  controls.

In this lesson, we learned about tracker.

2D tracker that allows you to extract animation data from the position, rotation, and size of an image. Using expressions, you can apply the data directly to transform and match-move another element. Or you can invert the values of the data and apply them to the original element – again through expressions – to stabilize the image.

Combine alpha

Channelmerge

The ChannelMerge node lets you merge together one channel from each input and save the result in the selected output channel. All other channels are copied unchanged from the B input.

If no A input is connected, both channels to merge are taken from the B input.

By default, ChannelMerge combines the inputs’ alphas.

Grade (pressing G on Node Graph)

Lets you define white and black points by sampling pixels from the Viewer. Setting the brightest parts of the image to pure white and the darkest to pure black in this manner can help you add punch to overexposed images, for example. You can also use this node for matching foreground plates to background plates.

To sample pixels from the Viewer, click on a color swatch to the right of the control you want to set. The eye dropper icon appears. In the Viewer:

1. Ctrl/Cmd+click to sample a single pixel from the node’s output.
2. Ctrl/Cmd+Shift+drag to sample a region of pixels from the node’s output.
3. Ctrl/Cmd+Alt+click to sample a single pixel from the node’s input while viewing its output.
4. Ctrl/Cmd+Alt+Shift+drag to sample a region of pixels from the node’s input while viewing its output.
5. Crtl/Cmd+ right-click cancels pixel selections.

Clamps

This node constrains, or clamps, values in the selected channels to a specified range. By default, it clamps all channels to values between 0 and 1. This can be useful for ensuring that the input’s blackest blacks and whitest whites will be visible on an intended display device, or for restricting data fed to a subsequent node that does not support numbers outside this range.

Reformat

Keymix

Keymix for green screen key:IBKcolor（A)+primatte(B)+roto(Mask）

This week, we learn how to roto and track from a vedio.

How we can remove the alpha?

Shuffle

1. rearrange up to 8 channels from a single image (B input). For example, you can use it to swap rgba.red for rgba.green, and vice versa,
2. rearrange channels between two separate nodes (A and B input), like a foreground and background branch,
3. replace a channel with black (removing the alpha channel, for example) or with white (making the alpha solid, for example),
4. create new channels.

Premult

By default, Premult multiplies the input’s rgb channels by its alpha (in other words, premultiplies the input image). You may need this node when:

1. Merging unpremultiplied images. Because Merge nodes in Nuke expect premultiplied images, you should use this node before any Merge operations if your input images are unpremultiplied. This avoids unwanted artifacts, such as fringing around masked objects.
2. Color correcting premultiplied images. When you color correct a premultiplied image, you should first connect an Unpremult node to the image to turn the image into an unpremultiplied one. Then, perform the color correction. Finally, add a Premult node to return the image to its original premultiplied state for Merge operations.

Typically, most 3D rendered images are premultiplied. As a rule of thumb, if the background is black or even just very dark, the image may be premultiplied.

Roto (pressing O on Node Graph)

The Roto node is an optimal choice if you’re doing rotoscoping only – it allows you to create and edit Bezier and B-spline shapes.

The toolbar on the left side of the Viewer includes point selection and manipulation, and shape creation tools. Click and hold or right-click on a toolbar button to open a sub-menu to select any of its available tool types. Options related to the current tool appear in a toolbar along the top of the Viewer. Click on a toolbar item to cycle through the available options for that class of tools.

As a general workflow guide:

1. Select your tool from the left-hand Viewer tool bar.

2. Use the Roto tool settings above the Viewer to adjust the tool’s properties.
3. Draw your shape or shapes:

• Click in the Viewer to place points. You can drag while clicking to pull out Bezier handles or adjust B-Spline tension.
• Ctrl/Cmd+drag to sketch the shape freely.
• To close the shape, click the first point or press Return. To leave the shape open, press Esc.
• Ctrl/Cmd+Alt+click to add points to an existing shape.
• To increase the smoothness of a point, select the point and press Z.
• To cusp a point, select the point and press Shift+Z.
• To delete a point, select the point and press Delete.
• Beziers: Shift+drag on a tangent handle to snap the opposite handle to the same length. Ctrl/Cmd+drag on a tangent handle to move it independently of its opposite handle.
• B-Splines: Ctrl/Cmd+Alt+drag on a point to adjust its tension.

4. Select a shape using the Select tools or the shape list in the control panel.
5. Use the control panel to adjust or fine-tune your shape(s).

Copy (pressing K on Node Graph)

Replaces channels in the B input with channels from the A input. You can use a mask channel to indicate which input is used for each pixel or whether both inputs should be mixed for some pixels.

In this lesson, we learned about what dose a digital compositor is.

I like this diagram, it interestingly explains the process of making 3d animation.

We learned the basics of Nuke such as import and export formats, colour modes, and other nodes for different purposes.

Import and Export

RGBA

ColorWheel

Generates a color wheel image. Inputs and Controls,the colors on the bottom pf the node show all the channels contained in the node.

CheckerBoard

Generates a checkerboard image that you can use as a placeholder for a texture or background. If you enable proxy mode the board may not match the full resolution version, because the boxes are rounded to the nearest pixel. Inputs and Controls.

ColorBars

Generates a Society of Motion Picture and Television Engineers (SMPTE) color bars test pattern, useful for color management. Inputs and Controls.

‘City’: I couldn’t think of an exact subject at first, I just randomly recorded some life clips,until I wanted to add background music to this 20-second video and I heard the song sparks. It suddenly remind to me that pets, art, music, and architecture are the sparks in our lives.