=Paper=
{{Paper
|id=None
|storemode=property
|title=Replicating Two TelePresence Camera Depth-of-Field Settings in One User Experience Study
|pdfUrl=https://ceur-ws.org/Vol-976/spaper6.pdf
|volume=Vol-976
|dblpUrl=https://dblp.org/rec/conf/chi/CarlsonPM13
}}
==Replicating Two TelePresence Camera Depth-of-Field Settings in One User Experience Study==
https://ceur-ws.org/Vol-976/spaper6.pdf
Replicating Two TelePresence Camera
Depth-of-Field Settings in One User
Experience Study
Jennifer Lee Carlson Abstract ACM Classification Keywords
Sr. User Experience Researcher This paper describes an H.4.3. Information Systems: INFORMATION SYSTEMS
Cisco Systems, Inc. experience study to APPLICATIONS: Communications Applications
170 W Tasman Drive understand the user
San Jose, CA 95134 USA perceptions on two General Terms
jennicar@cisco.com camera focus settings Human Factors, Experimentation, Design
in a TelePresence
Mike Paget room: limited- and Introduction
Sr. Technical Marketing Manager infinite-Depth-of-Field. Depth-of-Field is a description of the focal
Cisco Systems, Inc. The results influence characteristics within a captured image. It describes the
170 W Tasman Drive future TelePresence sharpness of the image from the foremost to farthest
San Jose, CA 95134 USA experience design. areas on the z-axis within the cameras field of view.
mpaget@cisco.com The cameras Depth-of-Field is determined by four key
Author Keywords factors which were related to works in this study:
Tim McCollum User experience; 1. The proximity of the two lenses to the camera
Sr. Design Manager comparative study; sensor and the cameras overall proximity to the
Cisco Systems, Inc. TelePresence; Depth- subject, otherwise known as focal length.
170 W Tasman Drive of-Field; video
San Jose, CA 95134 USA 2. The amount of light that is allowed to reach the
conferencing codec;
tmccollu@cisco.com sensor controlled by the aperture setting.
macroblocks; network
bandwidth 3. The duration at which light is allowed to pass
through the aperture, which is called shutter speed.
4. Camera gain setting, which can increase perceived
Presented at RepliCHI2013. Copyright © 2013 for the individual papers
brightness in the image.
by the papers’ authors. Copying permitted only for private and academic
purposes. This volume is published and copyrighted by its editors.
2 -2-
Two very common approaches to image capture additional processing power and bandwidth
produce very different resulting images under the same requirements but it doesn’t require the same tedious
environmental conditions. The approach of limited attention to detail of the environmental conditions or
Depth-of-Field is to limit the amount of focal area the camera settings. Therefore this approach offers a
within the image to achieve controlled focal points. more flexible deployment model for a wider range of
Generally this is an artistic decision for a particular conditions. In the case of the systems that utilized the
aesthetic style. This has also been used in video Precision HD camera, such as the Cisco TelePresence 3-
applications such as cinema for the same artistic series (T3) system, they shared the same camera for
purpose. However, in video applications such as both dedicated and multipurpose room systems.
conferencing, the same image characteristics have Therefore use of an infinite Depth-of-Field configuration
been used for a completely different purpose [1]. was preferable to allow greatest amount of flexibility.
Current video codecs used in conferencing systems
apply an algorithm that defines what information is The two depth-of-field applications were largely based
sent based on changed events rather than sending the on technical and business reasons. What are the user
entire image. The algorithm groups areas of experience impacts, if any, from the two camera
information together in macroblocks and sends these settings in a TelePresence room? Our usability study
chunked updates when an area of the macroblock has was to answer the following questions:
changed. This approach requires tedious preparation of 1. Are users aware of the difference in the two
the environmental conditions and the camera settings. camera focus approaches? If so, how do they differ?
In the case of the Cisco TelePresence System 3000-
2. Which approach feels more life-like to users? What
series (CTS-3xxx) system designs, they were purposely
made it more life-like?
built for a dedicated room that was optimized for very
high quality at a low network bandwidth. Therefore 3. Which approach do users prefer and why? Are
they followed the model of camera settings that there other considerations besides being life-like?
provided limited Depth-of-Field.
Methodology
On the other hand, the approach of infinite Depth-of- In August 2011 the Cisco TelePresence User Experience
Field, where a controlled focal point is not established, team conducted a formal usability study in an
is also common in both still image and video image immersive TelePresence room (see Figure 1).
capture. This approach captures more detail within the
resulting image and requires the viewer (or end user) The study replicated the two camera settings in the
to determine their own focal points as they view and same TelePresence room to evaluate the user
process the image. In a conferencing system this experience in the context of a meeting. During the
approach will capture objects within the camera’s field session, users focused on the moderator, no documents
of view, as they exist without the need to adjust the were shared, and the room had sufficient depth and
amount of sharpness. Such a system could require background to identify the moderator’s unique location.
3 -3-
We conducted a total of 27 within-subject comparative critical to make the other aspects of the images as
usability study [2] sessions, with each session lasting similar as possible, such as the field of view and the
approximately 15 minutes. All participants have subject matter within the frame. The two cameras
experience with TelePresence. (used for the CTS-3xxx and T3 systems) for which we
wanted to test had very different physical
characteristics. But it was important that users couldn’t
tell the different cameras by their physical appearances
from the room. It was not possible to house both types
of cameras within the same system. Therefore, one
camera type was selected that fit the appropriate
physical characteristics as well as possessed settings
that could achieve both a limited depth-of-field and
infinite depth-of-field.
Replicating the Depth-of-Field technique is relatively
easy in some areas and difficult in others. The lighting
and camera settings (hard and soft) can be replicated
easily with this controlled environment. The actual focal
Figure 1. Cisco TelePresence CTS-3000 System settings are more challenging because we didn't
actually measure the depth of field with any equipment.
Participants entered the TelePresence room containing It was assumed based on camera and light settings,
three side-by-side HD screens. The middle screen was and by looking at the two set-ups subjectively.
turned off during the entire study. The participant was However, if we were to focus more effort on measuring
seated in the middle of the room so that the left and the depth of field as to define the distance and amount
right screens were the same distance from their seat. of sharpness or blurriness, it could be more easily
The left screen displayed an infinite Depth-of-Field, replicated. The other area that was challenging to
where both moderator and background were in focus. replicate are the objects in the background. We setup
The right screen displayed a limited Depth-of-Field, similar background based on props we had available.
where the moderator was in focus but the background We could define more parameters on those props to
was blurred at a noticeable level. After the second day better replicate the testing.
of sessions (completed 15 participants) the background
objects were switched completely to counter-balance Procedures
any effects due to the background objects. Participants were told they would have a conversation
with a moderator via TelePresence to discuss their
In this study, in order to evaluate the user experience experience with TelePresence, provide feedback and
impact from the two depth-of-field settings, it was rate their experience. Participants were not informed of
4 -4-
the difference in camera approaches until after they moderator explained the differences between the
had separately provided feedback and rated both infinite and limited Depth-of-Field camera approaches.
views. They looked at one view at a time until the very With this knowledge, participants then rated how
end of the session when they compared the views side appealing each view was, which view they preferred
by side. and why.
The study itself was comprised of three separate A 7-point scale rating scale was used for all rating
elements: questions, where 1 represented the ‘worst’ rating and 7
Camera Setting 1 represented the ‘best’ rating.
Participants were first presented with a view (segment)
of the moderator on either the right or left screen (the Findings
order was reversed for every other participant to avoid The study has identified the following key findings
potential order effects). After answering TelePresence- based on participant behavior, feedback and preference
related questions for several minutes, participants were ratings:
asked to rate the TelePresence session in terms of 1. Approximately 93% (25 of 27) participants were
video quality and how lifelike it appeared. unable to distinguish the camera focus approaches on
Camera Setting 2 their own without viewing the images side by side.
Then the view was switched to the opposite side of the Even after viewing the images side by side, only 37%
room and the moderator moved to the displayed view (10 of 27) of participants were able to discern the
to interact with the participant. After several minutes difference in background clarity between the two views.
of additional conversation, the participants were again 2. Between the two camera focus approaches, on
asked to rate the video quality and lifelike appearance average there were very minimal perceived differences
of the view. in terms of being lifelike (5.93 for infinite Depth-of-
Comparisons Field vs. 5.86 for limited Depth-of-Field) and video
Participants were asked if they could tell any quality (6.32 for infinite Depth-of-Field vs. 6.29 for
differences between the two views they just looked at. limited Depth-of-Field.)
If there were any differences, how the two views 3. After understanding the camera focus difference:
appeared differently. Then they were shown both views More participants (11 of 27 or 40%) preferred the
- one at a time - and asked if they noticed any infinite Depth-of-Field approach. Fewer participants (8
difference, or if they have noticed any other of 27 or 30%) preferred the limited Depth-of-Field
differences. At the end, participants were shown both approach. Almost one-third (8 of 27 or 30%)
views simultaneously so that they could make direct participants did not have a preference between the two
comparisons. Participants were asked to describe any approaches. On average the infinite Depth-of-Field view
differences they observed. If the participant could not was rated slightly more appealing (5.93 for infinite
discern a difference in background clarity, the Depth-of-Field vs. 5.52 for limited Depth-of-Field).
5 -5-
Conclusion Acknowledgements
Camera’s Depth-of-Field setting is not a significant The authors thank all participants in Cisco Systems who
experience differentiator for an immersive TelePresence participated in the study described here. We also thank
room. Infinite Depth-of-Field could potentially provide a Laura Borns of Cambridge Consultants for her note-
more lifelike experience and perceived as better taking and analysis assistance for the study; Kevin
quality. Nguyen and Rick AtKisson of Cisco Systems for their
support in TelePresence room set-up for the study, and
Potential Future Work Chris Dunn of Cisco Systems, who initiated this
This study was meant to be the first of a series of research study and reviewed this submission.
studies. We want to find out what degree of camera
focus difference will be perceivable by most users. We References
also want to study and analyze how user’s preferences [1] O'hara, K., Kjeldskov, J., Paay, J., Blended
for camera focus relate to the different types of interaction spaces for distributed team collaboration. In
ACM Transactions on Computer-Human Interaction
meetings: such as an interactive brainstorming session,
(TOCHI) TOCHI Homepage archive, Volume 18 Issue 1,
a round-table team meeting, a single-speaker April 2011, Article No. 3.
presentation, or other types of meetings.
[2] Sauro, J., Lewis, J.R. Quantifying the User
Experience: Practical Statistics for User Research
One hypothesis was that users who are more technical (2012, ISBN-10: 0123849683 | ISBN-13: 978-
or goal oriented might show a stronger preference for 0123849687), 10-11.
limited Depth-of-Field because they might focus more
on the people than their environment; users who are
more artistic or context sensitive might show a stronger
preference for infinite Depth-of-Field because they care
more about the surroundings of whom they meet with.
There wasn’t any analysis on how the Depth-of-Field
preferences relate to participants’ job roles or
personalities.