Shake was the main compositing software used on The Two Towers. In fact, it is fair to say there was no shot that wouldn’t a t some point in the process go through Shake! Weta also has a Flame and an Inferno installed, as well as some other 2D packages that are mostly used in the paint/roto department (liberty 64, ER, commotion). We started out using v2.46, but
as soon as v2.5 got released as a beta, we tested it in the production environment and found it stable enough to be our main version of shake to use. (I know – quite daring!). The Mac OS X release happened so late in production that it wasn’t really possible to use it, especially since our renderwall is built around Linux servers; but we’re evaluating it at
Towards the end of production, the comp department consisted of ca. 50 artists, some of whom would actually work on more than one machine; in addition, TDs sometimes used shake to do quick bash comp of their Work in progress. So we had about 100 gui and 300 render licenses.
After Film 1, the workflow was significantly changed, especially in respect to the fact that a digital grade was happening as a post process, not at the beginning of the effects work. This resulted in Weta artists working in what we use to call “neutral space” – meaning that a gray card filmed on the live action set with white (neutral) light would be represented in equal RGB values in the digital world. This necessitated the generation of LUTs for each film stock used in production to offset their color bias, as well as a new set of Monitor LUTs to display the images properly.
Weta’s visual fx supervisor Joe Letteri was the key person behind this development.The Posthouse, who were responsible for the grading and conform of the film, also delivered us with a “prime grade” for each sequence, basically a rough version of the grade Peter Jackson was asking for in a specific sequence that could be used to see how shots would hold up eventually. This is an example of how well shake fit into our pipeline: as soon as PH finished a grade for a shot, it was published in their online database. Weta compositors were then able to copy-paste the color grade nodes from their web page directly into their shake scripts.
Since about 2/3 of the shots involved CG of one sort or the other, the need for a new File format for all CG renders arose, resulting in Weta’s own file format, lif. Development of this format began towards the end of FOTR, but it wasn’t until TTT that it was used facility wide on all shots. It’s is based on Maya’s iff format, but stores the color information a 16 bit log encoded, like a cineon file. Moreover, it can include DOD information that can be used by shake to reduce rendertime, and other shot specific information (which maya file was used for rendering etc.)
To make full use of the dynamic range stored in these images, it was decided to comp most shots in float. This workflow allows the user to convert a log encoded file to true linear without clipping or compromising image quality. Most of the dual proc linux boxes we use for interactive are so fast that the speed hit normally associated with float is negligible.
Story by Alex Lemke and Steven McKendry
Weta Digital Ltd.
Story submitted by Tülay Tetiker, contributing editor.