Stereoscopic displays are increasingly used for computer-aided design. The aim is to make virtual prototypes
to avoid building real ones, so that time, money and raw materials are saved. But do we really know whether
virtual displays render the objects in a realistic way to potential users?
In this study, we have performed several experiments in which we compare two virtual shapes to their
equivalent in the real world, each of these aiming at a specific issue by a comparison:
First, we performed some perception tests to evaluate the importance of head tracking to evaluate if it is
better to concentrate our efforts on stereoscopic vision;
Second, we have studied the effects of interpupillary distance;
Third, we studied the effects of the position of the main object in comparison with the screen.
Two different tests are used, the first one using a well-known shape (a sphere) and the second one using an
irregular shape but with almost the same colour and dimension. These two tests allow us to determine if
symmetry is important in their perception.
We show that head tracking has a more important effect on shape perception than stereoscopic vision,
especially on depth perception because the subject is able to move around the scene. The study also shows that
an object between the subject and the screen is perceived better than an object which is on the screen, even if
the latter is better for the eye strain.
KEYWORDS: 3D modeling, Photography, Visualization, Anisotropic filtering, Light sources and illumination, 3D image processing, Calibration, Digital photography, Visual process modeling, 3D image reconstruction
Lots of techniques exist to generate a 3D model given a limited set of photographs. Extracting depth information using stereoscopic correspondences generally outputs a large number of depth maps to be merged. Generating a dense representation of the object (shape-from-shading, level-set minimization) can be time-consuming. Shape-from-silhouettes and hybrid techniques, carving an approximate model given consistency constraints, suffer from a lack of scalability.
In the context of the GANTOM project, we developed a system based on an automatic turntable, high-resolution digital cameras (up to 4Mpixels) and accurate encoders to acquire the data. This allows us to perform a very fine calibration of the acquisition process, i.e. less than 0.5mm. In this paper, we present the GANTOM software system that can be subdivided into the following elements:
- Depth map extraction using stereoscopic correspondence. Different search spaces are compared.
- Depth map fusion using a voxel-based algorithm, called shape-from-depth, which is a generalization of shape-from-silhouettes.
- Conversion from a volumetric model to a polyhedral model.
- Texture extraction using the polyhedral model and the photographs as inputs.
As the scope of virtual reality applications including stereoscopic imaging becomes wider, it is quite clear that not every designer of a VR application thinks of its constraints in order to make a correct use of stereo. Stereoscopic imagery though not required can be a useful tool for depth perception. It is possible to limit the depth of field as shown by Perrin who has also undertaken research on the link between the ability of fusing stereoscopic images (stereopsis) and local disparity and spatial frequency content. We will show how we can extend and enhance this work especially on the computational complexity point of view. The wavelet theory allows us to define a local spatial frequency and then a local measure of stereoscopic comfort. This measure is based on local spatial frequency and disparity as well as on the observations made by Woepking. Local comfort estimation allows us to propose several filtering methods to enhance this comfort. The idea to modify the images such as they check a “stereoscopic comfort condition” defined as a threshold for the stereoscopic comfort condition. More technically, we seek to limit high spatial frequency content when disparity is high thanks to the use of fast algorithms.
In the car manufacturing industry the trend is to drastically reduce the time-to-market by increasing the use of the Digital Mock-up instead of physical prototypes. Design review and ergonomic studies are specific tasks because they involve qualitative or even subjective judgements. In this paper, we present IMAVE (IMmersion Adapted to a VEhicle) designed for immersive styling review, gaps visualization and simple ergonomic studies. We show that stereoscopic displays are necessary and must fulfill several constraints due to the proximity and size of the car dashboard. The duration fo the work sessions forces us to eliminate all vertical parallax, and 1:1 scale is obviously required for a valid immersion. Two demonstrators were realized allowing us to have a large set of testers (over 100). More than 80% of the testers saw an immediate use of the IMAVE system. We discuss the good and bad marks awarded to the system. Future work include being able to use several rear-projected stereo screens for doors and central console visualization, but without the parallax presently visible in some CAVE-like environments.
Conference Committee Involvement (3)
The Engineering Reality of Virtual Reality 2006
19 January 2006 | San Jose, California, United States
The Engineering Reality of Virtual Reality 2005
20 January 2005 | San Jose, California, United States
The Engineering Reality of Virtual Reality 2004
22 January 2004 | San Jose, California, United States
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