KEYWORDS: Cameras, 3D image processing, Cinematography, 3D displays, 3D acquisition, Light sources and illumination, Virtual reality, Image resolution, Stereoscopy, Visualization
While there have been numerous studies concerning human perception in stereoscopic environments, rules of
thumb for cinematography in stereoscopy have not yet been well-established. To that aim, we present experiments
and results of subject testing in a stereoscopic environment, similar to that of a theater (i.e. large flat
screen without head-tracking). In particular we wish to empirically identify thresholds at which different types
of backgrounds, referred to in the computer animation industry as matte paintings, can be used while still maintaining
the illusion of seamless perspective and depth for a particular scene and camera shot. In monoscopic
synthetic imagery, any type of matte painting that maintains proper perspective lines, depth cues, and coherent
lighting and textures saves in production costs while still maintaining the illusion of an alternate cinematic reality.
However, in stereoscopic synthetic imagery, a 2D matte painting that worked in monoscopy may fail to provide
the intended illusion of depth because the viewer has added depth information provided by stereopsis. We intend
to observe two stereoscopic perceptual thresholds in this study which will provide practical guidelines indicating
when to use each of three types of matte paintings. We ran subject tests in two virtual testing environments,
each with varying conditions. Data were collected showing how the choices of the users matched the correct
response, and the resulting perceptual threshold patterns are discussed below.
The wheel effect (also called the Wagon-wheel effect) is a well-known rotation illusion in which a rotating wheel, when
displayed as individual frames, appears to rotate differently from its true rotation due to temporal aliasing. In this paper,
we propose several approaches to solve this problem for synthetic imagery in computer animation. First, we develop an
algorithm to compute the frame number at which our visual perception starts to incorrectly interpret the wheel rotation.
By making this critical frame number available, we can correct the wheel rotation by manipulating its geometry while
viewers are unaware of the change. Our second approach is developed based on the Nyquist sampling theorem. We can
increase the sample rate to capture the essential deviation that correctly depicts the wheel rotation to take care of the
under-sampling issue. Our third approach is based on the traditional view that texture is often used to aid our motion
perception. We further identity certain rules that can be applied to the textures to distinguish the real motion from the
illusion. For each approach, we analyze both the advantages and disadvantages and suggest the potential applications.
In this paper we present experiments and results pertaining to the perception of depth in stereoscopic viewing
of synthetic imagery. In computer animation, typical synthetic imagery is highly textured and uses stylized
illumination of abstracted material models by abstracted light source models. While there have been numerous
studies concerning stereoscopic capabilities, conventions for staging and cinematography in stereoscopic movies
have not yet been well-established. Our long-term goal is to measure the effectiveness of various cinematography
techniques on the human visual system in a theatrical viewing environment. We would like to identify the
elements of stereoscopic cinema that are important in terms of enhancing the viewer's understanding of a scene
as well as providing guidelines for the cinematographer relating to storytelling.
In these experiments we isolated stereoscopic effects by eliminating as many other visual cues as is reasonable.
In particular, we aim to empirically determine what types of movement in synthetic imagery affect the perceptual
depth sensing capabilities of our viewers. Using synthetic imagery, we created several viewing scenarios in which
the viewer is asked to locate a target object's depth in a simple environment. The scenarios were specifically
designed to compare the effectiveness of stereo viewing, camera movement, and object motion in aiding depth
perception. Data were collected showing the error between the choice of the user and the actual depth value, and
patterns were identified that relate the test variables to the viewer's perceptual depth accuracy in our theatrical
viewing environment.
In any surveillance or remote monitoring system, the location and configuration/orientation of directed optical
sensors is critical for efficient resource utilization as well as correct system behavior. In this paper we introduce a
method to determine the set of configurations (pan-tilt-zoom) for a system of cameras in a given a 3D environment
with well-characterized human activity. The mainstay of our method is a metric that measures the ground plane
coverage by a sensor. Our goal is to seek configurations that provide maximal coverage of areas in a scene that
have been deemed important or have intense human activity. Our method was deployed on a portion large urban
campus covering a region with multiple buildings, sidewalks, trees and other occluding objects. We built a 3D
CAD model of the environment and tested our method on a system of six pan-tilt-zoom cameras. We used
activity information gathered from surveillance of the environment to determine the coverage requirements. The
resulting sensor configurations satisfied the real-world security and surveillance concerns of the environment.
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