Diffuse reflection model and noise stabilization for tangential image tomographic reconstruction (TITR) code

2009 ◽  
Vol 49 (7) ◽  
pp. 075032 ◽  
Author(s):  
Santanu Banerjee ◽  
P. Vasu
Keyword(s):  
Diffuse Reflection ◽  
Tomographic Reconstruction ◽  
Reflection Model

scholarly journals A New Method of Measuring Retinal Vessel Diameters from Fundus Photographs Based on Retinal Structure and Light Reflection

2021 ◽  
Author(s):  
Satoshi Wakebe ◽  
Kotaro Yamasue ◽  
Hidetoshi Itoh
Keyword(s):  
Blood Vessel ◽  
Diffuse Reflection ◽  
Repeated Measurement ◽  
New Method ◽  
Dimensional Structure ◽  
Cylindrical Shape ◽  
Reflection Model ◽  
Luminance Profile ◽  
Fundus Photographs ◽  
Minimum Points

<p>We propose a new method and software for measuring blood vessel diameters from fundus photographs. In this method the edge of the blood vessel is the two minimum points in the luminance profile and diameter is distance between minimum points. We noticed the relation between W-shape of luminance profile at blood vessel transversal line and cylindrical shape, and analyzed the validity of this method using the diffuse reflection model of a cylinder shape based on the optics. The simulation image by the diffuse reflection model of the cylinder was similar to that of the blood vessel images. A newly developed software using the minimum points can measure repeated measurement in a series of photographs at the same point of the same person. The data of the repeated measurement of each person showed stability, and the coefficient of variation showed no affection of different diameter and arteriovenous distinction. Hence, we believe that the minimum points are valid as blood vessel edges. The software that measures these blood vessel edges has an extremely simple measurement procedure, possesses few errors, and is easy to automate. This method is relevant because the central reflex, which has not been utilized previously, optically represents the cylindrical three-dimensional structure of blood vessels.</p><div><div> </div> </div>

scholarly journals A New Method of Measuring Retinal Vessel Diameters from Fundus Photographs Based on Retinal Structure and Light Reflection

2021 ◽  
Author(s):  
Satoshi Wakebe ◽  
Kotaro Yamasue ◽  
Hidetoshi Itoh
Keyword(s):  
Blood Vessel ◽  
Diffuse Reflection ◽  
Repeated Measurement ◽  
New Method ◽  
Dimensional Structure ◽  
Cylindrical Shape ◽  
Reflection Model ◽  
Luminance Profile ◽  
Fundus Photographs ◽  
Minimum Points

<p>We propose a new method and software for measuring blood vessel diameters from fundus photographs. In this method the edge of the blood vessel is the two minimum points in the luminance profile and diameter is distance between minimum points. We noticed the relation between W-shape of luminance profile at blood vessel transversal line and cylindrical shape, and analyzed the validity of this method using the diffuse reflection model of a cylinder shape based on the optics. The simulation image by the diffuse reflection model of the cylinder was similar to that of the blood vessel images. A newly developed software using the minimum points can measure repeated measurement in a series of photographs at the same point of the same person. The data of the repeated measurement of each person showed stability, and the coefficient of variation showed no affection of different diameter and arteriovenous distinction. Hence, we believe that the minimum points are valid as blood vessel edges. The software that measures these blood vessel edges has an extremely simple measurement procedure, possesses few errors, and is easy to automate. This method is relevant because the central reflex, which has not been utilized previously, optically represents the cylindrical three-dimensional structure of blood vessels.</p><div><div> </div> </div>

Development of a System to Measure the Optical Properties of Facial Skin using a 3D Camera and Projector

2021 ◽  
Author(s):  
Kumiko Kikuchi ◽  
Shoji Tominaga ◽  
Jon Y. Hardeberg
Keyword(s):  
Optical Properties ◽  
Diffuse Reflection ◽  
Specular Reflection ◽  
Three Dimensional ◽  
Depth Image ◽  
Facial Skin ◽  
Subsurface Scattering ◽  
Surface Reflection ◽  
Reflection Model ◽  
Reflection Component

We have developed a system to measure both the optical properties of facial skin and the three-dimensional shape of the face. To measure the three-dimensional facial shape, our system uses a light-field camera to provide a focused image and a depth image simultaneously. The light source uses a projector that produces a high-frequency binary illumination pattern to separate the subsurface scattering and surface reflections from the facial skin. Using a dichromatic reflection model, the surface reflection image of the skin can be separated further into a specular reflection component and a diffuse reflection component. Verification using physically controlled objects showed that the separation of the optical properties by the system correlated with the subsurface scattering, specular reflection, or diffuse reflection characteristics of each object. The method presented here opens new possibilities in cosmetology and skin pharmacology for measurement of the skin’s gloss and absorption kinetics and the pharmacodynamics of various external agents.

scholarly journals A collocation method for the Williams equation with Chebyshev polynomials

2021 ◽  
Vol 2056 (1) ◽  
pp. 012005
Author(s):  
O V Germider ◽  
V N Popov
Keyword(s):  
Collocation Method ◽  
Chebyshev Polynomials ◽  
Basic Equation ◽  
Gas Flow ◽  
Diffuse Reflection ◽  
Constant Pressure ◽  
Plane Channel ◽  
Reflection Model ◽  
Linearized Problem ◽  
The Given

Abstract The linearized problem of gas flow in plane channel with infinite walls has been solved in the kinetic approximation. The flow in the channel is caused by a constant pressure gradient parallel to the walls of the channel. The Williams equation has been used as a basic equation, and the boundary condition has been set in terms of the diffuse reflection model. The collocation method for Chebyshev polynomials has been applied to construct the solution of the equation of Williams with the given boundary conditions. The mass flux of the gas in the channel has been calculated.

scholarly journals Analytical solution to the problem of diffusion of the light component of the binary gas mixture in a plane channel

2021 ◽  
Vol 2056 (1) ◽  
pp. 012004
Author(s):  
V N Popov ◽  
I V Popov
Keyword(s):  
Analytical Solution ◽  
Flow Rate ◽  
Diffuse Reflection ◽  
Plane Channel ◽  
Boltzmann Kinetic Equation ◽  
Heavy Component ◽  
Light Component ◽  
Reflection Model ◽  
Binary Gas Mixture ◽  
Gas Component

Abstract Within the framework of the kinetic approach, an analytical solution to the problem of diffusion of the light component of a binary mixture in a flat channel with infinite parallel walls is constructed. It is assumed that the mass of light component molecules and their concentration is much less than the mass of molecules and the concentration of heavy components. The flow rate of the heavy component is assumed to be zero. The change in the state of a light gas component is described on the basis of the BGK (Bhatnagar, Gross, Kruk) model of the Boltzmann kinetic equation. The diffuse reflection model is used as a boundary condition on the channel walls. The mass velocity profile of the light gas component is constructed. The flow rate of the light gas component per unit channel width is calculated. A comparison with similar results presented in open sources was done.

scholarly journals Неизотермическое течение газа в эллиптическом канале с внутренним круговым цилиндрическим элементом в свободномолекулярном режиме

2019 ◽  
Vol 89 (1) ◽  
pp. 27
Author(s):  
О.В. Гермидер ◽  
В.Н. Попов
Keyword(s):  
Mass Flow ◽  
Basic Equation ◽  
Gas Flow ◽  
Diffuse Reflection ◽  
Boltzmann Kinetic Equation ◽  
Molecular Gas ◽  
Pressure Drops ◽  
Reflection Model ◽  
Linearized Problem ◽  
Temperature And Pressure

AbstractThe linearized problem of free-molecular gas flow in a long elliptic channel with a circular cylindrical element inside has been solved in the kinetic approximation. The flow in the channel is caused by temperature and pressure drops between its ends. The Boltzmann kinetic equation for collisionless gas has been used as a basic equation, and the boundary condition has been set in terms of the diffuse reflection model. The distribution of the mass velocity of the gas over the cross section of the channel has been obtained. The mass flow rate of the gas in the channel versus the temperature and pressure drops between its ends has been calculated. It has been found that the mass flow of the gas substantially depends on the radius of the inner cylinder.

Application of the Multi-Particle Collision Dynamics Method to a Suspension of Magnetic Spherical Particles

2017 ◽  
Author(s):  
Akira Satoh
Keyword(s):  
Brownian Motion ◽  
Magnetic Particles ◽  
Magnetic Particle ◽  
Diffuse Reflection ◽  
Spherical Particles ◽  
Particle Collision ◽  
Collision Dynamics ◽  
Reflection Model ◽  
Aggregate Structures ◽  
Rotational Brownian Motion

In order to apply the multi-particle collision dynamics (MPCD) method to a magnetic particle suspension, we have elucidated the dependence of the translational and rotational Brownian motion of magnetic particles on the MPCD parameters that characterize the MPCD simulation method. We here consider a two-dimensional system composed of magnetic spherical particles in thermodynamic equilibrium. The diffuse reflection model has been employed for treating the interactions between fluid and magnetic particles. In the diffuse reflection model, the interactions between fluid and magnetic particles are transferred into the translational motion more strongly than into the rotational motion of magnetic particles. The employment of relatively small simulation time steps gives rise to a satisfactory level of the translational Brownian motion. The activation level of the Brownian motion is almost independent of both the size of the unit collision cell and the number of fluid particles per cell. Larger values of the maximum rotation angle induce stronger translational and rotational Brownian motion, but in the present magnetic particle suspension the range between around π/4 and π/2 seems to be reasonable. We may conclude that the MPCD method with the simple diffuse reflection model is a feasible simulation technique as the first approximation for analyzing the behavior of magnetic particles in a suspension. If more accurate solutions regarding the aggregate structures of magnetic particles are required, the introduction of the scaling coefficient regarding the interactions between fluid and magnetic particles can yield more accurate and physically reasonable aggregate structures in both a qualitative and quantitative meanings.

Design and calibration of an IVEM for general 3-dimensional imaging of non-diffracting materials

1992 ◽  
Vol 50 (2) ◽  
pp. 1040-1041
Author(s):  
Neil Rowlands ◽  
Jeff Price ◽  
Michael Kersker ◽  
Seichi Suzuki ◽  
Steve Young ◽  
...  
Keyword(s):  
3D Imaging ◽  
Tomographic Reconstruction ◽  
Three Dimensional ◽  
3 Dimensional ◽  
3D Microstructure ◽  
Image Translation ◽  
Digital Correlation ◽  
On Line ◽  
Mechanical Stage ◽  
Projection Angle

Three-dimensional (3D) microstructure visualization on the electron microscope requires that the sample be tilted to different positions to collect a series of projections. This tilting should be performed rapidly for on-line stereo viewing and precisely for off-line tomographic reconstruction. Usually a projection series is collected using mechanical stage tilt alone. The stereo pairs must be viewed off-line and the 60 to 120 tomographic projections must be aligned with fiduciary markers or digital correlation methods. The delay in viewing stereo pairs and the alignment problems in tomographic reconstruction could be eliminated or improved by tilting the beam if such tilt could be accomplished without image translation.A microscope capable of beam tilt with simultaneous image shift to eliminate tilt-induced translation has been investigated for 3D imaging of thick (1 μm) biologic specimens. By tilting the beam above and through the specimen and bringing it back below the specimen, a brightfield image with a projection angle corresponding to the beam tilt angle can be recorded (Fig. 1a).

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