Marja Salmimaa

Optical characterization of autostereoscopic 3-D displays

— Display-measurement methods different from conventional 2-D display measurements are needed for verifying the optical characteristics of autostereoscopic (3-D) displays and for comparing different 3-D display technologies. Industry is lacking standardized measurement methods, and the reported results can not always be compared. The selected set of characteristics discussed in this paper and partly defining the quality of the 3-D experience are crosstalk, viewing freedom, and optimum viewing distance. Also, more conventional display characteristics such as luminance are discussed, since the definitions for these characteristics in 3-D mode usually differ from those used for the 2D displays. We have investigated how these chosen 3-D display characteristics can be objectively measured from transmissive two-view and multiview 3-D displays. The scope of this article is to generally define those basic characteristics as well as the different measurement methods. Most of the 3-D characteristics can be derived from the luminance and colors versus the viewing angle. Either a conoscopic or a goniometric measurement system can be used, as long as the angular and stray-light properties are suitable and known. The characteristics and methods are currently discussed in the display-quality standardization forums.

MEX: a distributed software architecture for wearable computers

A new dynamic software architecture for wearable computers is proposed. Key properties of this MEX architecture are examined and compared to some other existing software architecture. One application utilizing MEX, called WalkMap, is presented. The aim of the applications currently under development is to enhance the communication and cooperation of the users utilizing wearable computers in their daily lives. Based on that, the software components needed to access context information anywhere and the hardware requirements arising from constant usage are considered. The hardware platform for the software architecture developed is briefly described.

3-D crosstalk and luminance uniformity from angular luminance profiles of multiview autostereoscopic 3-D displays

Abstract— Autostereoscopic 3-D display technologies enable a more immersive media experience by adding real depth to the visual content. However, the method used for the creation of a sensation of depth or stereo illusion contains several display design and content-related issues that need to be carefully considered to maintain sufficient image quality. Conventionally, methods used for 3-D image-quality evaluations have been based on subjective testing. Optical measurements, in addition to subjective testing, can be used as an efficient tool for 3-D display characterization. Objective characterization methods for autostereoscopic displays have been developed. How parameters affecting stereo image quality can be defined and measured, and how their effect on the stereo image quality can be evaluated have been investigated. Developed characterization methods are based on empirically gathered data. In this paper, previously presented methodology for two-view displays is extended to cover autostereoscopic multiview displays. A distinction between displays where the change in content occurs in clear steps when the user moves in front of the display, and displays where the apparent movement of the objects is more continuous as a function of the head movement is made. Definitions for 3-D luminance and luminance uniformity, which are equally important, as well as 3-D crosstalk, which is the dominant factor in the evaluations of the perceived 3-D image quality, is focused upon.

Subjective measures of presence and discomfort in viewers of color‐separation‐based stereoscopic cinema

— The experience of various people related to a real 3-D cinema visit has been studied, and the results will be discussed. This study has two distinct parts, which includes the comfort of the viewers and their sense of presence. Eighty-four viewers filled out questionnaires about comfort and visual strain. Forty-one subjects described their presence experience during the movie presentation. A majority of the people felt comfortable after the movie viewing; they experienced only mild-eyestrain-related symptoms. People evaluated the movie world as highly realistic, but they did not feel that they were actors in the virtual-movie world. Most of the participants would recommend 3-D cinema to friends because it was a very entertaining experience.

Evaluating depth illusion as method of adding emphasis in autostereoscopic mobile displays

In this paper we evaluate the possibilities of autostereo-scopic three-dimensional displays in aiding the user in a selection task on a mobile touch-screen user interface. We describe a user study which measures the effectiveness of realistic depth illusion as an emphasizing method in a conventional mobile user interface concept. In our experiment, 35 people completed simple thumbnail visual search tasks, where horizontal disparity, color shading, and their combination were used as the emphasizing method. The results indicate that using disparity alone as a visual indicator does not provide enough support in find-and-select tasks to improve the user performance or perceived comfort with the task. However, when combined with other visual cues, disparity can significantly improve performance and satisfaction.

Effect of ambient illumination level on perceived autostereoscopic display quality and depth perception

Twenty participants viewed real-world videos and still images with a small hand-held autostereoscopic device in three ambient illuminations with three display luminance levels. Perceived depth, naturalness, overall image quality, and viewing discomfort were evaluated. The results show that illumination and luminance levels influence perceived quality parameters, but perceived depth is less sensitive to changes in ambient illumination than other viewing quality parameters associated with 3D viewing. Viewing 3D scenes lasting up to 40 min may cause some mild eyestrain symptoms, but symptoms of visually induced motion sickness are rare. The use of autostereoscopic hand-held devices therefore seems feasible in different contexts with different display luminance levels, and the overall viewing experience is relatively comfortable for most of the adult viewers.

Mobile 3D Video Using MVC and N800 Internet Tablet

The recent advances in capture, display and content representation technologies allow 3D video services to come to reality. In this paper, we present a prototype device that implements the emerging MVC standard on a portable device and achieves real-time 3D video operation. The developed prototype is based on Nokia N800 Internet Tablet and it is able to decode and display stereoscopic video simultaneously. To achieve this, an H.264/AVC decoder is first ported on the N800 environment with various optimizations and architectural changes, so that real-time decoding operation of two views is possible. The decoded pictures from different views are then interleaved and rendered on a screen with a parallax barrier. This way, the user is able to enjoy 3D video real-time on a mobile device. It is believed that this implementation is a realistic demonstration of the potential of upcoming mobile 3D video services, such as mobile 3DTV, mobile 3D video conferencing, etc.

Determining limits to avoid double vision in an autostereoscopic display: Disparity and image element width

— The purpose of this study was to investigate the diplopia limits for three-dimensional stereoscopic content and to determine the main methodological issues when the limits are studied with an autostereoscopic display. One of the main issues regarding stereoscopic content is the structural features that enable the user to see stereo image as a single image. If the depth of the content is not within certain limits, the perceiver cannot see the images three dimensionally and the viewing is uncomfortable. On the other hand, if these limits are followed, the user can stereoscopically fuse the images and see the resulting three-dimensional image correctly. Some of these limits were tested and guidelines for proper depth values for stereoscopic images will be presented.

Exploring the interaction design space for interactive glasses

In this paper, we explore the interaction design space for interactive glasses. We discuss general issues with interactive glasses (i.e., optics, technology, social, form factors), and then concentrate on the topic of the nature of interaction with glasses and its implications to provide a delightful user experience with the NotifEye.

Reading experience with curved hand‐held displays

— The aim of this study was to measure reading experiences on curved paper-like displays. The experimental materials were mockups that consisted of printed paper attached to a curved plastic surface. The experiment participants held the mockups in their hands and evaluated the reading experience with them. Twelve font sizes, two curvature magnitudes, and two curvature directions were used in the experiment. The results showed that reading text on a curved surface was easier when the curvature direction is perpendicular to the text direction. It was also found that concave surfaces were regarded as better in cases where the text direction was the same as the curvature direction.