WEEK 3, 4 & 5: Theory & introduction to the Nuke interface
We were initially introduced to the concept of Cinematography, and it’s relevance to Visual Effects artists and Animators. More specifically regarding cameras, we went through the basics, including exposure, aperture, camera shutter, ISO etc and what each of them mean.
We also discussed the ‘depth of field’ and the factors that affect it, and concluding with how these factors can help to achieve The Cinematic Look
We were introduced to the concept of mise-en-scene, and the importance of the film-maker to convey meaning and mood through composition. To make a successful composition, the Ruse of Thirds is often referred to. It acts as a guide to place essential elements in the shot.
We also looked at shot selection, a way in which filmmakers have categorised different shots depending on the size of the elements in frame, from close up to medium to full shot, and when they are appropriate to use.
The use of light was also discussed, in particular the intensity and quality of it. The two main categories being Hard and Soft light. We looked at examples of these.
After learning all the theory, we were introduced and became familiar with the Nuke interface.
WEEK 6: Rotoscoping
This week we learnt the basics of rotoscoping in Nuke. We were intorduced to the Roto node, and how to organise our workspace.
Rotoscoping is the technique of manually creating a matte for an element on a live-action plate, in order for it to be composited onto another background.
We create these ‘mattes’ as an alpha channel, to match the motion on the footage. We were working on a plate of a running man, I attempted to rotoscope the feet first, we were introduced to the different bezier tools we could use to draw around our objects. It ended up being a frame by frame job, and very time-consuming so I will continue the roto at a later date.
WEEK 7: Merging and Colour
We firstly learnt the basis of ‘Pre-multiplication’ in Nuke, and when we would need to apply this to our plate. Before any Merge takes place you must check if the image is pre-multiplied, and when applying a ColourCorrect you must un-premult.
We then covered the different Merging Operations, including mask, stencil, overlay etc.
Additionally we were introduced to the Grading Nodes, in particular we used the Grade and ColourCorrect options.
The method in which to colour correct a plate is to initially balance out the primary colour, then the secondary colours, and finally the shadows.
We were tasked with seamlessly blending a plane onto a dusk backdrop, using the colour correction nodes we had learnt. The image needed to be unpremultiplied first, then I used Grade to..
I then used the ColourCorrect to affect the shadows, highlights and mid-tones. Using the picker to try and correspond the colours in the backdrop to the plane. I assumed the highlights and mid-tones would be more vlue tinged, whereas the shadows would lean more towards orange.
I feel it is quite difficult to get an accurate colour on the image. It is too red tinged at the moment, It should be more subtly orange in my opinion.
WEEK 8: 2D Tracking
This week we attempted 2D tracking. We were tasked with replacing the green screen on the phone with an image.
Firstly, I tracked the 4 corners of the phone with the tracker tool, then exported them to create a ‘CornerPin2D‘ node to apply to the new image. This allows the image to follow the same track.
Once completed, I used the transform tool to get an accurate overlay on the green screen. I am finding it difficult to get the exact fit, particularly around the top of the phone, where parts of the green can still be seen. I used EdgeBlur to create a seamless look to the screen.
I then copied the plate, and rotoscoped all three fingers that go over the screen, using the Bezier tool to ensure the shape is accurate. Then used a premultiply and merge to get the correct layering of the clip.
After roughly rotoscoping the fingers, I went back to ensure that each frame was done well, then used the EdgeBlur to create a softer and more realistic look.
WEEK 9-10: Planar Tracking
We started this class with discussing the importance of grouping in Nuke, with transforms and grades separated in order not to disrupt the plate, and to preserve the quality.
We also looked at the BBOX (Bounding Box), it is important in showing us the area that Nuke is calculating within, in order to consistently keep the right size plate we must pay attention to it. We were shown ways in which to control it, for example using ‘crop’ before merging elements and using a ‘roto’ changing the settings to A side etc. This ensures your script is kept light.
We then looked at the ‘shuffle’ node, and ways in which it gets used. For example changing the RGB colour output, and applying the depth of an image to the alpha. It allows you to work on separate channels.
In terms of planar tracking, we were shown how to replace the posters on a street view. It also had elements that needed to be cut out from in front of the footage, then rotoscoped back onto it.