What follows is a report from a student group using the Green Screen as a Previsualisation studio.
Real-Time Previs Experience Feedback
We used two different scenes to test the Previsualisation setup in the Green Screen studio. We realised an exterior environment with bright sunlight and sharp shadows, and an interior environment with more diffused lighting.
With the Unreal Engine setup, we were able to get a live feedback of a “slap comp” so that all cast and crew could see the live action footage overlayed to the CG background and with additional CG foreground elements. This approach helped us to make more aware choices about framing, composition, camera movements and lighting.
We prepared a custom output system, so we could record at the same time the already mentioned “slap comp”, the background and the foreground CG elements from Unreal (we used these to have a more refined comp for our work-in-progress edit), the clean plate from the camera for the traditional postproduction process and the camera track information from the motion capture system.
We were given a great setup, anyway during the process we faced many little and big technical issues. For example, some of our props (e.g.: sand) reflected IR light, which caused a loss of accuracy in the Motion Capture system. To fix this, we had to reconfigure the IR cameras on set, and to do a lot of clean up over the motion data. We came across many little problems in terms of acquisition of the Unreal Engine render passes in real time, colour space management from one system to the other, image streams resolution compatibility… After the first full day of work, we ended up with only fifteen seconds of footage, and it was not good enough to be used anyway, but eventually we got (almost) everything working.
Some of the outdoor scene assets are from a previous group project, and great thanks for those go to Dermott Burns, Edward Barnes, Alexandra Kim Bui, Alexander Lechev, Ollie Nicholls. Finally, of course a huge thank you to the people who gave us this incredible opportunity and helped us with any minute they had. Thank you to Richard Southern, Oleg Fryazinov, Neil Goridge, Edward Sedgley.
Cast & Crew
- Paolo Mercogliano – Director, UE Technician, Technology and pipeline supervisor
- Diana Pelino – Producer, Motion Capture Technician, VFX supervisor
- Joseph Adams – UE Technician
- Nathalie Puetzer – Camera operator, Compositor
- Miguel Pozas – 3D Assets, Effects, and Rendering, Actor
- Anna Semple – 3D Assets, Effects, and Rendering, Actress
In this video we demonstrate the progression from the slap comp in real time on set, to a more refined comp using the UE4 assets (this can be done in few minutes, to have a shot to use in a work-in-progress edit), to the final piece with a traditional offline render.