The effects of viewpoint on the virtual space of pictures

Pictorial displays whose primary purpose is to convey accurate information about the 3-D spatial layout of an environment are discussed. How and how well, pictures can convey such information is discussed. It is suggested that picture perception is not best approached as a unitary, indivisible process. Rather, it is a complex process depending on multiple, partially redundant, interacting sources of visual information for both the real surface of the picture and the virtual space beyond. Each picture must be assessed for the particular information that it makes available. This will determine how accurately the virtual space represented by the picture is seen, as well as how it is distorted when seen from the wrong viewpoint

Does Perceived Angular Declination Contribute To Perceived Optical Slant On Level Ground?

When one looks at a spot on level ground, the local optical slant (i.e., surface orientation relative to the line of sight) is geometrically equivalent to the angular declination (i.e., sagittal visual direction relative to horizontal). In theory, angular declination provides an unbiased proximal source of information for estimating optical slant on level ground. Two experiments were conducted to investigate whether human visual systems take advantage of this information. An aspect ratio task was used as an implicit measure for assessing perceived optical slant. Participants gave verbal estimates of the perceived aspect ratio of an L-shaped arrangement, formed by three balls on level ground or on slanted surfaces (hills). Gaze direction was held horizontal when viewing the stimuli on hills. Experiment 1 examined two optical slants (22° to 35°) at relatively short viewing distances (3.1 to 11.5 m), while Experiment 2 tested a shallow optical slant (6°) at relatively long viewing distances (5.7 to 17.2 m). No significant difference in perceived aspect ratio was found between the level-ground and the hill conditions in either experiment. These findings suggest that angular declination does not contribute to perceived optical slant on level ground. It seems that the perception of optical slant and of gaze declination are independent, and this may be because the two variables are normally used jointly to determine a higher order perceptual variable—geographical slant

Nuevas evidencias sobre la anisotropía del espacio visual y la influencia del entorno en el rendimiento visual

Desde hace años se han realizado múltiples investigaciones que tratan sobre la fiabilidad de la percepción de las distancias en profundidad y la influencia del entorno. En ocasiones, las pistas presentes en el espacio visual entran en conflicto y/o su interpretación conduce a sesgos y errores, produciendo efectos ilusorios al no corresponder las medidas físicas con las percibidas. El objetivo global de esta tesis doctoral ha sido poner de manifiesto nuevas evidencias de la anisotropía del espacio visual y de la influencia del entorno en relación al juicio de distancias entre objetos. Para ello, se han diseñado y ejecutado tres grupos de experimentos cuyos objetivos parciales fueron: Analizar el rol de las disparidades verticales en tareas de juicio de distancias relativas entre objetos situados en diferentes planos de profundidad, en función de la orientación del estímulo. Determinar la influencia del fondo y de la orientación del estímulo en tareas de juicio de distancias relativas entre objetos, situados en un mismo plano frontoparalelo o en diferentes planos de profundidad. Verificar la naturaleza neural de la anisotropía del espacio visual desde un enfoque psicofísico no invasivo mediante el uso de SIRDS. Los resultados obtenidos en esta tesis contribuyen a la comprensión sobre la integración de claves en Visión Binocular y los sesgos visuales perceptivos en la percepción de distancias.Recent decades have witnessed multiple studies investigating the accuracy of our visual system in depth perception, as well as the influence of environmental factors during depth judgment tasks. It is not uncommon for Virtual Space cues to offer contradictory or conflicting information, thus leading to bias and error, which in turn originate illusory effects resulting from discrepancies between real and perceived dimensions. Our research in the integration of cues in Binocular Vision aimed at determining the influence of background characteristics (curved, flat, etc) on the perception of visual stimuli presented over it. Therefore, three different experimental settings were designed and conducted, with partial objectives defined as follows: To evaluate the influence of vertical disparities in depth judgment tasks when stimuli were located at different depth planes and presented different orientations. To determine the influence of background configuration and stimulus orientation on depth judgment tasks, both with stimuli at the same frontoparallel plane or at different depth planes. To evidence the neural origin of the Visual Space anisotropy from a non invasive psychophysical approach with the use of SIRDS. The findings of the present PhD thesis contribute to our understanding of the integration of cues in Binocular Vision, as well as of the nature of visual bias in depth perception

Spatial Displays and Spatial Instruments

The conference proceedings topics are divided into two main areas: (1) issues of spatial and picture perception raised by graphical electronic displays of spatial information; and (2) design questions raised by the practical experience of designers actually defining new spatial instruments for use in new aircraft and spacecraft. Each topic is considered from both a theoretical and an applied direction. Emphasis is placed on discussion of phenomena and determination of design principles