Towards Generating Personalized Volumetric Phantom from Patient’s Surface Geometry

2018 ◽  
pp. 171-179 ◽  
Author(s):  
Yifan Wu ◽  
Vivek Singh ◽  
Brian Teixeira ◽  
Kai Ma ◽  
Birgi Tamersoy ◽  
...  
Keyword(s):  
Surface Geometry

Perceived Glossiness: Beyond Surface Properties

2019 ◽  
Vol 2019 (1) ◽  
pp. 37-42
Author(s):  
Davit Gigilashvili ◽  
Jean-Baptiste Thomas ◽  
Marius Pedersen ◽  
Jon Yngve Hardeberg
Keyword(s):  
Surface Properties ◽  
Human Subjects ◽  
Surface Geometry ◽  
Surface Reflection ◽  
Different Color

Gloss is widely accepted as a surface- and illuminationbased property, both by definition and by means of metrology. However, mechanisms of gloss perception are yet to be fully understood. Potential cues generating gloss perception can be a product of phenomena other than surface reflection and can vary from person to person. While human observers are less likely to be capable of inverting optics, they might also fail predicting the origin of the cues. Therefore, we hypothesize that color and translucency could also impact perceived glossiness. In order to validate our hypothesis, we conducted series of psychophysical experiments asking observers to rank objects by their glossiness. The objects had the identical surface geometry and shape but different color and translucency. The experiments have demonstrated that people do not perceive objects with identical surface equally glossy. Human subjects are usually able to rank objects of identical surface by their glossiness. However, the strategy used for ranking varies across the groups of people.

scholarly journals Temporal coherency of mechanical stimuli modulates tactile form perception

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Masashi Nakatani ◽  
Yasuaki Kobayashi ◽  
Kota Ohno ◽  
Masaaki Uesaka ◽  
Sayako Mogami ◽  
...  
Keyword(s):  
Sensory Neuron ◽  
Sensory Neurons ◽  
Contact Surface ◽  
Relative Magnitude ◽  
Form Perception ◽  
Tangential Displacement ◽  
Surface Geometry ◽  
Tactile Stimuli ◽  
Surface Patterns ◽  
Temporal Coherency

AbstractThe human hand can detect both form and texture information of a contact surface. The detection of skin displacement (sustained stimulus) and changes in skin displacement (transient stimulus) are thought to be mediated in different tactile channels; however, tactile form perception may use both types of information. Here, we studied whether both the temporal frequency and the temporal coherency information of tactile stimuli encoded in sensory neurons could be used to recognize the form of contact surfaces. We used the fishbone tactile illusion (FTI), a known tactile phenomenon, as a probe for tactile form perception in humans. This illusion typically occurs with a surface geometry that has a smooth bar and coarse textures in its adjacent areas. When stroking the central bar back and forth with a fingertip, a human observer perceives a hollow surface geometry even though the bar is physically flat. We used a passive high-density pin matrix to extract only the vertical information of the contact surface, suppressing tangential displacement from surface rubbing. Participants in the psychological experiment reported indented surface geometry by tracing over the FTI textures with pin matrices of the different spatial densities (1.0 and 2.0 mm pin intervals). Human participants reported that the relative magnitude of perceived surface indentation steeply decreased when pins in the adjacent areas vibrated in synchrony. To address possible mechanisms for tactile form perception in the FTI, we developed a computational model of sensory neurons to estimate temporal patterns of action potentials from tactile receptive fields. Our computational data suggest that (1) the temporal asynchrony of sensory neuron responses is correlated with the relative magnitude of perceived surface indentation and (2) the spatiotemporal change of displacements in tactile stimuli are correlated with the asynchrony of simulated sensory neuron responses for the fishbone surface patterns. Based on these results, we propose that both the frequency and the asynchrony of temporal activity in sensory neurons could produce tactile form perception.

Comparing Convex Region-of-Interest Selection Techniques for Surface Geometry

2019 ◽  
Author(s):  
Bret Jackson ◽  
Kayla Beckham ◽  
Anael Kuperwajs Cohen ◽  
Brianna C. Heggeseth
Keyword(s):  
Region Of Interest ◽  
Convex Region ◽  
Surface Geometry

scholarly journals Arbitrary-order intrinsic virtual element method for elliptic equations on surfaces

CALCOLO ◽  
2021 ◽  
Vol 58 (3) ◽  
Author(s):  
Elena Bachini ◽  
Gianmarco Manzini ◽  
Mario Putti
Keyword(s):  
Arbitrary Order ◽  
Surface Geometry ◽  
Virtual Element Method ◽  
Anisotropic Character ◽  
Local Reference System ◽  
Local Reference ◽  
Local Parametrization ◽  
Manufactured Solution ◽  
Virtual Element ◽  
Element Method

AbstractWe develop a geometrically intrinsic formulation of the arbitrary-order Virtual Element Method (VEM) on polygonal cells for the numerical solution of elliptic surface partial differential equations (PDEs). The PDE is first written in covariant form using an appropriate local reference system. The knowledge of the local parametrization allows us to consider the two-dimensional VEM scheme, without any explicit approximation of the surface geometry. The theoretical properties of the classical VEM are extended to our framework by taking into consideration the highly anisotropic character of the final discretization. These properties are extensively tested on triangular and polygonal meshes using a manufactured solution. The limitations of the scheme are verified as functions of the regularity of the surface and its approximation.

The Atomic Geometry of the Reconstructed (001) Surface of the Rutile Phase of SnO2

1989 ◽  
Vol 159 ◽  
Author(s):  
Charles B. Duke ◽  
Michael R. Thompson
Keyword(s):  
Energy Barrier ◽  
Tight Binding ◽  
Rutile Phase ◽  
Tetrahedral Coordination ◽  
Surface Geometry ◽  
Coordinate Surface ◽  
Rutile Structure ◽  
Reconstructed Surface ◽  
Distorted Tetrahedral Coordination ◽  
Stable Structures

AbstractThe tight-binding total energy formalism developed for tetrahedrally coordinated compound semiconductors has been extended to rutile-structure oxides and applied to calculate the surface atomic geometry and electronic structure of SnO2 (001). Two stable structures, separated by an energy barrier, are found. The first consists of slightly relaxed surface geometry with the top layer oxygen atoms relaxed outward by approximately 0.12A, and cations inward by 0.25A. The second geometry is a more massively reconstructed surface in which the four-coordinate surface Sn atoms attain highly distorted tetrahedral coordination.

scholarly journals A Surface Geometry Model for LiDAR Depth Completion

2021 ◽  
pp. 1-1
Author(s):  
Yiming Zhao ◽  
Lin Bai ◽  
Ziming Zhang ◽  
Xinming Huang
Keyword(s):  
Surface Geometry ◽  
Geometry Model

scholarly journals Visualizing High-Order Surface Geometry

2009 ◽  
Vol 6 (2) ◽  
pp. 263-268
Author(s):  
Pushkar P. Joshi ◽  
Carlo H. Séquin
Keyword(s):  
High Order ◽  
Surface Geometry ◽  
Order Surface

Novel Electronics Enabled by Rare Earth Arsenides Buried in III-V Semiconductors

1993 ◽  
Vol 301 ◽  
Author(s):  
S. James Allen ◽  
Dan Brehmer ◽  
C.J. PalmstrØm
Keyword(s):  
Rare Earth ◽  
Epitaxial Layers ◽  
Hot Electron ◽  
Surface Geometry ◽  
Electron Effective Mass ◽  
Metal Base ◽  
Lattice Match ◽  
Linear Material ◽  
Shubnikov De Haas Oscillations ◽  
Electron Transistors

ABSTRACTHeterostructures consisting of III-V semiconductors and epitaxial layers of the rare earth monoarsenides can be grown by molecular beam epitaxy. By alloying ErAs with ScAs, lattice match can be achieved with (Al,Ga)As. Using magneto-transport measurements, we show that these layers are semi-metallic with equal electron and hole concentrations, 3.0 ×1020 cm−3. Shubnikov-de Haas oscillations are used to confirm the predicted Fermi surface geometry and measure the electron effective mass and the coupling to the 4f spin on the Er3+ ion. Remarkably, the material shows no transition from semimetal to semiconductor as the film thickness is reduced to three monolayers. Below three monolayers the films are not uniform and are believed to consist of islands three monolayers high.This system provides a unique opportunity to explore novel electronics based on controlled transport through semimetal/semiconductor heterostructures. Lateral transport through semimetal islands immersed in a δ-doped layer may provide a fast non-linear material for THz electronics. Vertical transport through thin epitaxial layers may enable resonant tunneling hot electron transistors with a semi-metal base. Preliminary experiments on transistor like test structures measure some transfer through a 10 monolayer thick semimetal base. They also identify overgrowth of the III-V semiconductor on the semimetal layer as the key materials issue.

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