Canonical Viewpoints Research Articles

Viewpoint dependence and scene context effects generalize to depth rotated three-dimensional objects.

Viewpoint effects on object recognition interact with object-scene consistency effects. While recognition of objects seen from "noncanonical" viewpoints (e.g., a cup from below) is typically impeded compared to processing of objects seen from canonical viewpoints (e.g., the string-side of a guitar), this effect is reduced by meaningful scene context information. In the present study we investigated if these findings established by using photographic images, generalize to strongly noncanonical orientations of three-dimensional (3D) models of objects. Using 3D models allowed us to probe a broad range of viewpoints and empirically establish viewpoints with very strong noncanonical and canonical orientations. In Experiment 1, we presented 3D models of objects from six different viewpoints (0°, 60°, 120°, 180° 240°, 300°) in color (1a) and grayscaled (1b) in a sequential matching task. Viewpoint had a significant effect on accuracy and response times. Based on the viewpoint effect in Experiments 1a and 1b, we could empirically determine the most canonical and noncanonical viewpoints from our set of viewpoints to use in Experiment 2. In Experiment 2, participants again performed a sequential matching task, however now the objects were paired with scene backgrounds which could be either consistent (e.g., a cup in the kitchen) or inconsistent (e.g., a guitar in the bathroom) to the object. Viewpoint interacted significantly with scene consistency in that object recognition was less affected by viewpoint when consistent scene information was provided, compared to inconsistent information. Our results show that scene context supports object recognition even when using extremely noncanonical orientations of depth rotated 3D objects. This supports the important role object-scene processing plays for object constancy especially under conditions of high uncertainty.

Typical viewpoints of objects are better detected than atypical ones.

Previous work has claimed that canonical viewpoints of objects are more readily perceived than noncanonical viewpoints. However, all of these studies required participants to identify the object, a late perceptual process at best and arguably a cognitive process (Pylyshyn, 1999). Here, we extend this work to early vision by removing the explicit need to identify the objects. In particular, we asked participants to make an intact/scrambled discrimination of briefly presented objects that were viewed from either typical or atypical viewpoints. Notably, participants did not have to identify the object; only discriminate it from noise (scrambled). Participants were more sensitive in discriminating objects presented in typically encountered orientations than when objects were presented in atypical depth rotations (Experiment 1). However, the same effect for objects presented in atypical picture plane rotations (as opposed to typical ones) did not reach statistical significance (Experiments 2 and 3), suggesting that particular informative views may play a critical role in this effect. We interpret this enhanced perceptibility, for both these items and good exemplars and probable scenes, as deriving from their high real-world statistical regularity.

Tactile line drawings for improved shape understanding in blind and visually impaired users

Members of the blind and visually impaired community rely heavily on tactile illustrations - raised line graphics on paper that are felt by hand - to understand geometric ideas in school textbooks, depict a story in children's books, or conceptualize exhibits in museums. However, these illustrations often fail to achieve their goals, in large part due to the lack of understanding in how 3D shapes can be represented in 2D projections. This paper describes a new technique to design tactile illustrations considering the needs of blind individuals. Successful illustration design of 3D objects presupposes identification and combination of important information in topology and geometry. We propose a twofold approach to improve shape understanding. First, we introduce a part-based multi-projection rendering strategy to display geometric information of 3D shapes, making use of canonical viewpoints and removing reliance on traditional perspective projections. Second, curvature information is extracted from cross sections and embedded as textures in our illustrations.

Similarity Voting based Viewpoint Selection for Volumes

AbstractPrevious viewpoint selection methods in volume visualization are generally based on some deterministic measures of viewpoint quality. However, they may not express the familiarity and aesthetic sense of users for features of interest. In this paper, we propose an image‐based viewpoint selection model to learn how visualization experts choose representative viewpoints for volumes with similar features. For a given volume, we first collect images with similar features, and these images reflect the viewpoint preferences of the experts when visualizing these features. Each collected image tallies votes to the viewpoints with the best matching based on an image similarity measure, which evaluates the spatial shape and appearance similarity between the collected image and the rendered image from the viewpoint. The optimal viewpoint is the one with the most votes from the collected images, that is, the viewpoint chosen by most visualization experts for similar features. We performed experiments on various volumes available in volume visualization, and made comparisons with traditional viewpoint selection methods. The results demonstrate that our model can select more canonical viewpoints, which are consistent with human perception.

Canonical Viewpoints for Videos of Assembly Tasks

Canonical Viewpoints for Videos of Assembly Tasks

Engaging the Image of Art, Culture, and Philosophy: Particular Perspectives on Ethiopian Modernity and Modernism

As the editors of Callaloo said in the February 2010 Ethiopia issue, “Appraising the literature, life, and culture of Ethiopia is a daunting undertaking. Like its history, Ethiopia’s literary and cultural traditions are so vast, and so rich, that they exceed the grasp of a single volume.”1 Indeed, many volumes of critical texts of Ethiopia’s influential history are needed to illustrate the range of images that conjure up Ethiopia. The specific complexities of Ethiopian modernity and modernism are often circumscribed by canonical viewpoints and often confused by scholars with conventional preconceptions of processes of modernization, complicit in projects of nation and empire. Existing scholarship frequently neglects to construct the processes of modernity within the discursive space of its multiplicity and cultural specificity. This issue is yet another investigation that can possibly shed light to the nation’s untapped body of knowledge and discursive practices from scholars across academic disciplines. These essays, from various

Canonical views of dynamic scenes.

The visual recognition of dynamic scenes was examined. The authors hypothesized that the notion of canonical views, which has received strong empirical support for static objects, also holds for dynamic scenes. In Experiment 1, viewpoints orthogonal to the main axis of movement in the scene were preferred over other viewpoints, whereas viewpoints in line with the main axis were least preferred. Experiment 2 provided no empirical evidence for a recognition advantage of canonical viewpoints when presented during the initial learning phase, but Experiment 3 showed a cognitive advantage for canonical viewpoints if they were presented as test stimuli during the recognition test. Overall, the findings suggest that on a phenomenological level, viewers are consciously aware of such viewpoints, and, on a cognitive level, viewers benefit from canonical viewpoints in terms of recognition accuracy.

Memory for objects in canonical and noncanonical viewpoints

This article investigates how the perspective from which we see an object affects memory. Object identification can be affected by the orientation of the object. Palmer, Rosch, and Chase (1981) coined the term canonical to describe perspectives in which identification performance is best. We present two experiments that tested the effects of object perspective on memory. Our results revealed a double dissociation between task (recognition and recall) and type of object perspective. In recognition, items studied in the noncanonical viewpoint produced higher proportions of "old" responses than did items studied in the canonical viewpoint, whereas new objects presented from a noncanonical viewpoint produced fewer "old" responses than did new objects presented from the canonical viewpoint. In free recall, conversely, objects studied from the noncanonical viewpoint produced lower recall rates than did objects studied from the canonical viewpoint. These results, which reveal a pattern similar to word frequency effects, support the psychological reality of canonical viewpoints and the frequency-of-exposure-based accounts of canonical viewpoint effects.

Is recognition of visual sequences better if canonical viewpoints are used?

Is recognition of visual sequences better if canonical viewpoints are used?

Age Degradation in Top-Down Processing: Identifying Objects from Canonical and Noncanonical Viewpoints

Twenty-four young (mean age 21.8 years) and 24 old (mean age 65.2years) participants were asked to determine whether spoken words correctly named pictures of objects. Half of the objects were portrayed from noncanonical (unusual) viewpoints, and half were portrayed from canon ical viewpoints. The older participants required more time and made more errors when they evaluated the noncanonical pictures (relative to the canonical pictures) than the younger participants. This finding is consistent with previous evidence that frontal lobe function degrades with aging and with results from a positron emission tomography study (S.M. Kosslyn et al., 1994) that showed that the frontal lobes (among other areas) are activated more in the noncanonical condition than in the canonical condition.

Generalized Hamiltonian theory: Central coordinates

The basis of a generalized formalism of Hamilton-Lagrange mechanics for elementary (i.e., individual) open systems was introduced in a previous work. In the present paper a covariance theory is constructed for the proposed generalization. The result is an extended transformation theory, or geometry, for phase space, in which the behavior of generalized Hamiltonian equations under time-dependent general coordinate transformations is determined. The proposed mechanics subsumes the ordinary mechanics in a natural way. New features include generalization of "pictures" (coordinate-system classes for fixed values of the Hamiltonian) to "viewpoints," which are characterized by values of a phase-space "vorticity" tensor, that always vanishes in ordinary mechanics: analogous to extremes of Heisenberg and Schr\"odinger pictures are those of canonical and Hamiltonian viewpoints. The Liouville theorem receives a novel generalization, and the scheme possesses a (viewpoint) covariant time derivative with analogies to the covariant derivative in a Riemannian space. Viewpoint covariance in the new formalism is the natural extension of canonical covariance in the old. The role of dynamical gauge invariance, investigated in a second previous paper, is elaborated, and the example of the undriven damped oscillator worked out to illustrate the operation of the formalism, including that of a generalized Hamilton-Jacobi theory. A line-element-space (Finslerian) interpretation is given for the new scheme, and a corresponding generalization is proposed for nonlinear self-interacting systems.