Nira's VFX Blog
A journey through my master

Tag: Nuke

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Nuke VFX Fundamentals

Week 5: Tracking and Premultiplication in Nuke

In this lecture, we saw the technique used to track the camera movement in a scene and how to combine or premultiply several sequences.

In order to track the movement of a scene, we can add tracking points in Nuke that will detect the camera movement. This is a useful tool for rotoscoping since we will not have to adjust the roto in every single frame because of the camera shake. Sometimes it is important to add several tracking points as the camera movement will be different in the foreground, middleground, and background because of the motion parallax.

In another note, we can also combine several elements like rotos together in Nuke with a ‘merge’ node. However, it is important to keep in mind that the alpha channel value always has to be between 0.0 and 1.0. This can be sorted changing the way that the layers interact with each other, with settings like ‘screen’, ‘over’, ‘max’, etc. ‘Channel merge’ nods can also be used for this but they are not as reliable as the ‘merge’ nods.

When layering scenes, there is a tool that it is used in most of the cases called ‘Premult’. This tool premultiplies the RGB values by the alpha so the two layers are visible at the same time. It is also important to combine ‘Premult’ node with ‘Copy’ to add the alpha to the background.

The assignment this week was to rotoscope the bridge from the running man’s video and the mountain from the air balloon project using tracking points.

Tracker point
Translate values of tracker transferred to roto
Final roto
Final set up
Running man final roto
Mountain roto
3 tracker points added to take in consideration depth
QC with grey background
QC with green overlay
Final set up
Mountain roto
Categories
Nuke VFX Fundamentals

Week 4: Rotoscoping in Nuke

In this class we discovered the basics of rotoscoping in Nuke.

Rotoscoping is used to create alpha channels ‘matte’ to match the footage motion. With this, we can change the subjects background or create different effects with layering.

In Nuke, we learnt the basic rotoscoping using ‘Beziers’ to create the alpha channel and feathering to soften the edges of it.

This is the matte I created of the running man video the professor sent to us. It is made by parts, starting from the head of the running man down till the legs.

Head roto
Right arm roto
Left arm roto
Body roto
Right leg roto
Left leg roto
Quality Check
Final roto

Rotoscoping can be a tedious job in my opinion but with practice and experience it could result in a more quick and pleasant job, as well as in a rewarding experience with the final result achieved.

Categories
Nuke VFX Fundamentals

Week 3: Intro to Digital Compositing and Nuke Software Interface

In this session, we discovered the different roles of a digital compositor within a production or VFX company, along with the production stages to follow to create a film, video game, commercial, etc. We also saw the different compositing programmes available nowadays and we also had our first Nuke overview.

A Digital Compositor’s role is to create the final composition of a frame, shot or sequence (including animation, background, graphics, and SFX). The several rolls or stages that a digital compositor can opt to are the following:

  • Roto Artist – focused in rotoscoping (beginner position)
  • Prep Artist – rotoscoping and patching
  • Junior/Junior-mid/senior Digital Compositor – they usually put the parts together in a scene and support and help Roto and Prep Artists
  • Sequence Lead or Lead Compositor – in charge of a sequence
  • 2D Supervisor – organises sequences, meets with final clients, etc
  • VFX Supervisor – organises artists, clients and production

On another note, we also learnt that there are three stages to produce a film:

  • Pre-production – starting from the initial idea that is shaped into a story which is organised in a storyboard, with animatic, and design.
  • Production – after the film is organised, in this stage it is prepared the layout, R&D, modelling, texturing, rigging/setup, animation, VFX, lighting, and rendering.
  • Post-production – in this third stage is when it is taking place the compositing, 2D VFX and/or motion graphics, colour correction, which will result in the final output.

Lastly, we saw the different compositing programmes available such as After Effects, Davinci Resolve ‘Fusion’, and Nuke 13. In this class, we will be focusing in Nuke so we had an overview of the very basic tools of the programme and created our first composition. As this programme is based in nods and layers, which I have seen before in programmes such as Photoshop, After Effects, and Blender, it was easy for me to learn how nods were connected to work together. I played around a bit with the programme at home later on and created a little animation based on the instructions the professor gave to us. I could not export it as I’m still not sure how to do this but I took some screenshots of how it looked at the end.

My first comp in Nuke
Comp animation outcome – center spin
Comp animation outcome – centrer spin

My first impression of Nuke is that this is complex programme and I will need to dedicate a good amount of practice time to get use to the node’s work space, as I am more use to layered programmes like Photoshop and After Effects.