Nuke W8 – Planar tracking, Filters, Blur & Defocus

Concatenation is the ability to perform one single mathematical calculation across several tools in the Transform family. This single calculation (or filter) allows us to retain as much detail as possible.

Example: http://www.nukepedia.com/written-tutorials/concatenation-of-transforms-in-nuke

– do not put grade/color correct in between transform node as it decreases the quality of the footage / more blurry
– the only filter matters for transform node is the filter at the end of the chain
– the only motion blur for transform node is the motion blur at the end of the chain
– use clone (alt+K) if you want to adjust multiple objects at the same time using the same value → saves time and avoids having to change nodes individually.
– most of the time you’ll be using cubic as filtering

Bounding Box BBOX = area where nuke will read and render information from
Plate > S = project setting

3 ways to match bounding box:

1. use crop node after transform node if your bounding box exceeds the root resolution so Nuke doesnt read information outside of the format
2. use merge node → change set bbox from union (default) to B
3. if use roto node → copy alpha → alpha → premult = it will automatically match bbox to roto

Working with 3D

• Press tab in viewer to switch between viewport to camera view
• hold ctrl + left click to orbit
• using reformat node to limit bbox to the size of original 3D elements in the scene

Shuffle node

Shuffle node represents the input layer – output layer
Shuffle create new channels for output and read different layers from many inputs both internal like the ones we created, but also multi-channel EXR renders where there are multiple LAYERS and multiple CHANNELS per image.
→ useful for manipulate rgba channel + depth

PLANAR TRACKER (perspective shift / 2.5 tracking)

PlanarTracker is good for perspective shift, but not for spacial movement

if there’s an object in the front, top viewer drop down → add new track layer, roto it and remember to put its folder ON TOP of the roto folder of the object behind. This will tell Nuke to exclude tracking the object in the front.
– absolute: shrink the source image
– relative: shrink the source image less

Zdefocus

Zdefocus node uses a focal point to generate bokeh, creating more of a film look than the Blur node.
Cons:
– Elements are a bit fake by eyes
– NukeX 14 has Bokeh node, which uses camera’s information so it’s more accurate to the eyes

For this week assignment, I need to use Planartrack node to replace the 2 posters in a scene that has perspective shift. I first didn’t understand why the CornerPin and the posters’ corners were not matching, then I learned that I have to click on the Premult node first before adding the CornerPin, so it will be generated from the poster itself. Then I roto the pole and added it back on top of the poster.

As a final touch, I attempted to replace the wall with a brick wall texture using what I have learned about Planar Tracking. I tracked the frames/windows around the poster, then track the wall using the same technique as the posters’ replacement. The result turned out quite nice as the color matches with the whole scene, but I think the image texture is still too sharp and not perfectly blended with the wall so it looks just a bit off.

A major problem that I had was not really understanding how to stabilize the brick wall texture so it doesn’t move with the camera shift. I have tried Stabilizing from Tracking, and also using teacher’s advice to try tracking the wall using smaller area instead of tracking the whole wall like I did at first, yet it’s still not working at all. I might have to revisit this project to figure this out.