This paper presents an efficient computational method to identify a local symmetry axis in 3-dimensional viral structures obtained using electron cryomicroscopy. Local symmetry is frequently observed in viral structures. Many virus structures have various types of local symmetry such as 2-fold, 3-fold and 6-fold that exist in certain limited regions on the 3-dimensional structure. Locations of ...

Symmetry detection is an interesting probe of pattern processing because it requires the matching of novel patterns without the benefit of prior recognition. However, there is evidence that prior knowledge of the axis location plays an important role in symmetry detection. We investigated how the prior information about the symmetry axis affects symmetry detection under noise-masking conditions...

In this paper, we investigate the exact method of searching an axis of binary image symmetry, based on brute-force search among all potential symmetry axes. As a measure of symmetry, we use the set-theoretic Jaccard similarity applied to two subsets of pixels of the image which is divided by some axis. Brute-force search algorithm definitely finds the axis of approximate symmetry which could be...

The role of color in the visual perception of mirror-symmetry is controversial. Some reports support the existence of color-selective mirror-symmetry channels, others that mirror-symmetry perception is merely sensitive to color-correlations across the symmetry axis. Here we test between the two ideas. Stimuli consisted of colored Gaussian-blobs arranged either mirror-symmetrically or quasi-rand...

S U M M A R Y We derive the explicit expressions for the phase velocities and polarizations of quasi-shear waves propagating in a transversely isotropic medium. The normal to the plane defined by the phase normal and the symmetry axis gives the exact polarization of S1, while the polarization of S2 also depends on the elastic parameters of the medium and is thus more complicated. Therefore, we ...

or perhaps with the face of our mother or father. We quickly learn to identify the axis of symmetry and know intuitively that an object is symmetric if it “the same” on both sides of this axis. In mathematics symmetry is abundant and takes many forms. Symmetry like that of the butterfly or a face is referred to as reflexive symmetry. Any line in the plane determines a unique symmetry which refl...

We investigated whether three-dimensional (3D) information in a scene can affect symmetry detection. The stimuli were random dot patterns with 15% dot density. We measured the coherence threshold, or the proportion of dots that were the mirror reflection of the other dots in the other half of the image about a central vertical axis, at 75% accuracy with a 2AFC paradigm under various 3D configur...

For each n ≥ 4 we show how to construct simple Venn diagrams of n curves embedded on the sphere with the following sets of isometries: (a) a 4-fold rotational symmetry about the polar axis, together with an additional involutional symmetry about an axis through the equator, and (b) an involutional symmetry about the polar axis together with two reflectional symmetries about orthogonal planes th...

This paper examines the role of spatial frequency and orientation tuned channels in the perception of visual symmetry. Subjects discriminated between band-pass filtered, white noise textures that either did or did not contain vertical bilateral symmetry (VBS, i.e., around a vertical midline) as a function of the spatial phase disruption imposed on the images. Resistance to phase noise is largel...