Framestore’s New Stereo Triage Process Takes Off with ‘The Martian’ |
The recent film ‘The Martian’ was the first application of a new stereo Triage process at Framestore visual effects studio. Their 2D supervisor Bronwyn Edwards, who has varied experience in native stereoscopic productions, worked to develop and put the new pipelines into action for the project. |
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Maths, Art and FilmThe new pipeline was based on The Foundry Ocula software, and the work was carried out by a team of compositors and paint and rotoscope artists. Over time, Bronwyn and the team successfully refined the processes to reach a quality that would stand up to external stereographic standards. |
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“Maths, art and film are three topics that interest me and what contributed to my decision to become a compositor,” Bronwyn said. “My first native stereo job was at MPC on ‘47 Ronin’. When applying for a job at Framestore, Christian Manz interviewed me and had also been the overall VFX Supervisor for ‘47 Ronin’. This movie was also I learned native stereo compositing - prior to that I had only been involved in stereo for conversion.” Since ‘Triage’ is the industry standard name for the correction of colour and vertical misalignments between the two eyes of a native stereo shot, Bronwyn likes to think of it as a technical process of understanding vision. She also notes a creative element, which involves making non-quantitative choices about how an image should look in order to invoke a desired response in the viewer. |
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Two-Way BenefitApart from perfecting the pipeline for Framestore, the work made a great opportunity for the artists on the team to learn about the structure and effect of 3D stereo images. “Almost everyone on the Paint & Roto and Compositing team worked on the Triage. The process gets everyone up to speed with stereo compositing, which means that by the time we are in creative shot production, the stereo compositing side of things becomes just part of our everyday working life,” Bronwyn said. “Ideally we try and schedule so that the artists get to do the Triage on the shots that they will be taking to final, but this isn’t always practical,” said Bronwyn. |
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Every single shot requires colour and vertical alignment. All plates are analysed initially by eye to look at what the most challenging aspects of the alignment will be. This informs the scheduling of the shots and if tracking is required before the alignment process begins. A simple shot may take a day, while a complex one can run into weeks of work. |
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Triage ToolsThe Ocula application the team were using for the work is made up of lots of different plug-ins, two or three of which were especially useful on ‘The Martian’. Among these, vertical aligner allows for different types of vertical alignment based on either corner pins or warps, using the incident points identified by the osolver. Most Ocula plugins rely on the incident points tracked by the osolver plug-in, and therefore it is also essential when using Ocula for alignment. Bronwyn said, “In terms of colour alignment, colour aligner is a very powerful tool that, in most cases, will achieve a 90% match out of the box. However in high end image manipulation, it is the final 5% and 1% that define a very high quality result. Consequently, colour alignment is also done manually in certain scenarios.” |
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Stereoscopic DisciplineOnce the triage is complete and the actual compositing and beauty work on shots takes off, procedural operations such as colour corrections and filters are carried out correctly in both eyes. Any additional layers and mattes must be placed very accurately relative to the geometry of the scene. Bronwyn emphasized that compositors should periodically check that what they are doing is working correctly in both eyes so that they don’t end up in a situation where a shot is approved in mono and the work on the hero eye will not carry through into the non-hero eye. |
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“This means that stereo compositing must be more disciplined than mono compositing. This increase in the compositor's discipline when working the comp can result in a better finished product - that is, a composite that hasn’t been constructed in a technically correct way may work for mono, but not for stereo and it could be argued that something built on firm and correct foundations allows for an improved creative expression.” www.framestore.com |