Improved Motion Blur in Computer Animated Film and Special Effects
Submitting InstitutionBournemouth University
Unit of AssessmentArt and Design: History, Practice and Theory
Summary Impact TypeTechnological
Research Subject Area(s)
Information and Computing Sciences: Artificial Intelligence and Image Processing
Medical and Health Sciences: Neurosciences
Summary of the impact
Motion blur is the effect that occurs when objects are filmed at speed.
Researchers at Bournemouth University's (BU) National Centre for Computer
Animation (NCCA) developed a new approach to more accurately model this
effect in 3D image production. This produces aesthetically superior images
without any penalty in rendering time. The technique was implemented by
Pixar in their own films and in the commercial PRMan software they supply
to other animation and effects studios in New Zealand, Canada, the USA and
the UK, among others. As well as contributing significantly to Pixar's
revenue, the technique improves the viewing experience and has been used
on virtually every major feature film produced since 2008. This
contributes to the global animation industry worth $207 US billion (2012,
In 2011 the NCCA won the Queen's Anniversary Prize for Higher and Further
Education in recognition of its contribution to world-leading excellence
and pioneering development in computer animation.
A clear example of this industry-shaping work is the research by
Stephenson (BU 1998 to present) who has focused on developing new
techniques to produce and render higher quality 3D images for feature film
production. The techniques were collectively published in P1, made up of
presentations at academic and commercial forums and journal publications
The main techniques emerging from the research are as follows:
- Anti-aliased noise to reduce artefacts when rendering rough or organic
- Vector texturing to allow vector artwork to be directly used within the
3D rendering process (P5).
- File compression techniques to significantly reduce file size without
compromising quality (P6).
- Use of volumetric point clouds (P7) for rendering volumetric effects
such as smoke.
- Motion blur (P2&P3).
The improved technique for producing motion blur was first presented in
2005 at the SIGGRAPH conference (P3).
It was later published in more detail in the Journal of Graphics Tools
(P2). The research improved computer graphic representations of objects
moving at speed.
A real camera records an image over a period of time, which leads to a
blurring. Previously, software rendering systems captured a scene at a
single instant and the lack of blurring appeared unnatural. Early motion
blur techniques reflected the camera capturing light over a period of
time, but failed to account for the fact that the shutter itself is a
physical device which takes time to open and close. This approach was used
without significant modification for over 20 years.
The publication of Stephenson's techniques in 2005 and 2007 marked a
profound shift in practice for the industry. By incorporating the "slow"
physical movement of a real shutter into computer graphics rendering
software, Stephenson produced images that were much more closely matched
to those of a real camera. In addition to being more physically faithful
to a real camera the new technique produces better images. The approach is
aesthetically better and improvements can be clearly seen in the images.
Mathematical analysis of the approach using sampling theory also shows the
results are theoretically better.
Traditional motion blur methods check the position of each moving object
at regular time intervals while the shutter is open. The new technique can
easily be integrated into existing software by adjusting the times at
which the object's position is tested. According to a specific mapping,
the effect of a low efficiency shutter can be simulated. This re-mapping
of sample times can be done very quickly, in comparison to the time taken
to actually test an object's position. This means there are no measurable
effects on render times. The technique is simple to implement, with
increased creative control and image quality.
References to the research
P1. Stephenson, I. (ed.) (2003). Production Rendering, Design
and Implementation. Springer. ISBN: 978-185-233821-3
P2. Stephenson, I. (2007). Improving Motion Blur: Shutter
Efficiency and Temporal Sampling. Journal of Graphic Tools, 12(1),
9-15. DOI: 10.1080/2151237X.2007.10129235.
SIGGRAPH originally stood for Special Interest Group on Computer Graphics
and Interactive Techniques when it was first established 40 years ago. It
has now progressed significantly from a `group' to an annual conference
attracting between 20,000 and 30,000 technical and creative professionals
from around the world. SIGGRAPH is widely recognized as the most
prestigious forum for the publication of computer graphics research and is
the most significant route for knowledge transfer between academia and the
computer graphics profession.
P3. Stephenson, I. (2005). Shutter efficiency and temporal
sampling. In: International Conference on Computer Graphics and
Interactive Techniques. ACM SIGGRAPH 2005 Sketches. SESSION:
Cinematography, 31 July-4 August 2005, Los Angeles, California. Article
101. DOI: 10.1145/1187112.1187234.
Available from: http://dl.acm.org/citation.cfm?doid=1187112.1187234
[accessed 21 November 2013].
P5. Haddon, J. and Stephenson, I. (2001). Vector Texturing. In: International
Conference on Computer Graphics and Interactive Techniques. ACM SIGGRAPH
Pixar User Group
This is an annual event organized by Pixar to coincide with the SIGGRAPH
conference, attended by RenderMan users from major effects and animation
studios. Users are invited to submit novel techniques and a small number
are invited to present each year.
Details of the impact
Stephenson's work has had a range of impacts on the industry. The
publicly released source code for the anti-aliased noise research has been
used at a number of studios and led to commercial rendering systems
introducing their own variants (P3); vector texturing techniques allowed
2D vector artwork to be directly applied to 3D surfaces, which was
implemented by Pixar in 2011 (P4); file compression techniques were used
at Core Studios, Toronto to significantly reduce their disk space usage
The most significant impact though is that of Stephenson's motion blur
research. The NCCA made the full implementation details publically
available in an `open source' format, with the intention that the approach
could be widely adopted.
Following the SIGGRAPH 2005 presentation, Stephenson entered discussions
with Pixar about his new techniques for motion blur. The Vice President of
PRMan Products and a number of software developers were present. In 2007,
Pixar implemented "Slow Shutter Opening/Timing" in their Photorealistic
RenderMan (PRMan) Softwarewith the first films to use the technique
emerging in 2008. The shutter opening controls were announced as a "Major
New Feature" of PRMan 13 (R2).
In an email to BU, dated 27/07/2011, the Business Director for PRMan at
Pixar said: "The Shutter Opening feature in Pixar's RenderMan software
derived significant inspiration from the SIGGRAPH 2005 Sketch and JGT [Journal
of Graphic Tools] 07 paper on Motion Blur authored by Ian Stephenson
of Bournemouth University." He concludes: "The influence of this work on
the development of the Shutter Opening Feature is fully acknowledged by
Pixar Animation Studios'' (R3).
PRMan is used to produce all of Pixar's films as well as being
commercially sold to other animation and digital effects production
companies. Though motion blur is only one aspect of the highly complex
techniques used for rendering, attention to detail at this level is what
distinguishes high end commercial systems such as PRMan. Pixar's
promotional material for their PRMan software specifically highlights the
improved Motion Blur as one of its key features, describing shutter timing
as "an innovative creative control for artistically sculpting the fall-off
of blur" (R4&R5).
The first Pixar animation to make use of Shutter Opening was in
production of the short film, Presto, released in 2008. Director, Doug
Sweetland considered that appropriate motion blur was essential for the
story and was very specific about the type of effect he wanted. Shutter
opening was the feature that made the film possible. He describes the new
approach as "critical [for creating the] specific look", providing
"creative control [and allowing the] creative vision to be realised" (R4).
Presto was used in the opening for the animated film Wall-E in 3,992
theatres in the US alone. Wall-E's worldwide gross was in the region of
$521,311,860 (R6). Presto itself was nominated for an Academy Award and an
Annie for Best Short film. In Internet Movie Database's (IMDb) list of
best short films of all time, Presto received the highest rating (R7).
Following the success of the technique in Presto, Pixar began producing
Cars 2, which was released in 2011. Motion Blur was used extensively in
the film, which was more dependent on high speed action than any previous
Pixar film. Cars 2 has a worldwide gross of $559,852,396 (R8).
Pixar are an important software developer within the film industry (R4)
and their software has been used by 49 out of the last 53 nominees for
Visual Effects Academy Award. They sell their PRMan rendering software to
most of the major digital effects studios. The extensive reach of the
software is evident through their international clients, which include
Digital Domain, USA; Weta Digital, New Zealand; Moving Picture Company
(MPC), USA and Canada; Industrial Light and Magic (ILM) UK; Framestore (UK
and USA), Cinesite, UK and Double Negative, UK among others. PRman
currently costs $2000 per copy, plus $600 annual maintenance. Studios such
as these require thousands of copies each; generating significant revenue
Through its inclusion within PRMan, the Shutter Timing technique is now
part of the software used on virtually every major feature film production
including (in 2012 alone): The Avengers, Bourne Legacy, Brave, The Dark
Night, The Hobbit, Jon Carter, Life of Pi, Men in Black 3, Prometheus,
Ted, Total Recall and Skyfall (R9).
Though motion blur is a tiny part of these projects, the films alone
generated billions of dollars in revenue and were viewed by hundreds of
millions of people. Artists working on them recognise the importance of
small details and, although the average audience member may not be able to
explicitly identify them, they contribute significantly to the viewing
experience. This in turn contributes to the global animation industry
worth $207 US billion.
Sources to corroborate the impact
R1. Global Animation Industry: Strategies, Trends and
Opportunities Report 2013. Research and markets value of animation
industry in 2012. Available from
R2. PhotoRealistic RenderMan 13.0 release notes. Available from:
R3. Email from Business Director of RenderMan, Pixar Animation
Studios, 27 July 2011. Available on request.
R4. Renderman product information (available on request).
R5. RenderMan motion blur and depth of field: http://renderman.pixar.com/view/motion-blur-and-depth-of-field.
R6. Financial information from Wall-E, Box Office Mojo. Available
R7. IMDb (2011) Best Short Films Ever. Available from: http://www.imdb.com/list/hobeL74d0rM/.
R8. Financial information from Cars 2, Box Office Mojo. Available
R9. RenderMan, The Industry Standard: http://renderman.pixar.com/view/movies-and-awards.