MSU Graphics & Media Lab Report #7 on stereo films quality assessment
The stereo 3D (S3D) film industry is stagnating. And one of the major factors behind it is the eyestrain and headaches commonly experienced by the viewers due to poor quality of produced S3D content. The Graphics & Media Lab CMC of Lomonosov Moscow State University (further: the Lab) has already published 6 reports since March 2013 investigating this problem and assessing technical quality of various S3D films.
The 1, 2, 4 reports were focused on films captured with stereoscopic camera systems, and the main problems discovered during the film analysis were:
- excessive horizontal disparity
- vertical disparity
- color mismatch
- sharpness mismatch
Third and fifth reports were dedicated to quality analysis of 2D-3D conversion which introduces a lot of new problems that are absent in captured S3D video. The analysis included the following common converted S3D video issues:
- the cardboard effect
- edge-sharpness mismatch
The sixth report introduced the comprehensive analysis of the stereo-window violation issue (Image #1) and the use of floating windows in stereoscopic films both from technical and creative perspectives. This problem often receives very little attention, while addressing it is crucial for delivering high-quality S3D content. It can greatly benefit from careful planning of the shooting and it is another factor that contributes to the overall importance of proper pre-production in stereoscopy.
Image #1: Example of a stereo-window violation
And now we would like to introduce the seventh report, where we continue to investigate different strategies for dealing with stereo-window violations and use of floating windows as a creative tool (Image #2). The report includes the following films:
- Step Up Revolution
- Resident Evil: Retribution
- A Very Harold & Kumar 3D Christmas
- Green Lantern
- Conan the Barbarian
- Wrath of the Titans
- Alice in Wonderland
The report presents per-frame charts that enable the analysis of floating window behaviour with respect to disparity of the closest object near the edge of the frame (Image #2). The charts are accompanied by visualizations of the most noticeable window violations.
Image #2: Example of a per-frame chart, illustrating the active use of dynamic positive-parallax floating windows in Pina. Such floating windows are usually used to further enhance the perception of depth in a scene.
The overall comparison of films now includes all 20 films analyzed in sixth and seventh reports.
Image #3: Stereo Window Violation vs. Release Date
Image #4: Stereo Window Violation vs. Floating Window Usage Intensity
Films with intense floating-window use generally have less prominent stereo-window violations. Several movies, however, achieved low number of noticeable stereo-window violations without using floating windows, which means that some alternative techniques were used. The most common approaches include: intentional darkening shot’s edges which can lessen the negative effect of stereo-window violations, shifting the overall parallax range of the film towards positive values and careful pre-production to minimize the number of shots where negative-parallax objects appear near the sides of the screen.
Image #5: Stereo Window Violation vs. Closest Object Disparity
Movies like The Three Musketeers, Green Lantern and Wrath of the Titans have a lot fewer objects in negative parallax near the edges of the screen, that led to good stereo-window-violation handling quality without using floating windows.
We would like to thank the following people for providing valuable comments, opinions and feedback, which helped to improve this report:
- Marcus Alexander, Stereoscopic Designer, 3D Producer
- Olivier Cahen, Stereoscopic Consultant, Author
- Ross Copeland, Online Editor / Stereographer & Colourist, Post-Production Consultant
- Markus Lanxinger, Stereographer, Stereoscopic Supervisor
- Daniele Pugni, 3D Motion Graphic Designer Freelancer for Sky 3D Channel
- Enrico Perei, On-Set/Post Production Stereographer, VFX Supervisor
- Fabien Remblier, S3D and 4K Director, Stereographer, Producer
- Wesley Sewell, Stereographic Supervisor
- Thomas Villepoux, Director, Stereographer
A key motive of our reports is to improve the stereo quality and therefore to reduce eyestrain and headache. The Graphics & Media Lab hopes that a high 3D video quality would contribute to a continually increasing number of people, leaving the modern theaters without annoyance and with good impressions from the image quality and storytelling.
We are always interested in feedback from professionals in film-production industry. We have already collaborated with more than 20 stereographers who provided us valuable comments which were inserted in our reports. If you would like to participate in the next reports, please feel free to contact us: firstname.lastname@example.org.
Stereo-analysis project description
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