scholarly journals A Novel Real-Time Match-Moving Method with HoloLens

2019 ◽  
Vol 9 (14) ◽  
pp. 2889 ◽  
Author(s):  
Jaehyun Lee ◽  
Jahanzeb Hafeez ◽  
Kwangjib Kim ◽  
Seunghyun Lee ◽  
Soonchul Kwon
Keyword(s):  
New Media ◽  
Focal Length ◽  
Image Synthesis ◽  
Motion Blur ◽  
Real Image ◽  
Virtual Camera ◽  
Spatial Understanding ◽  
Conventional Methods ◽  
Microsoft Hololens ◽  
Video Compositing

With the advancement of media and computing technologies, video compositing techniques have improved to a great extent. These techniques have been used not only in the entertainment industry but also in advertisement and new media. Match-moving is a cinematic technology in virtual-real image synthesis that allows the insertion of computer graphics (virtual objects) into real world scenes. To make a realistic virtual-real image synthesis, it is important to obtain internal parameters (such as focal length) and external parameters (position and rotation) from an Red-Green-Blue(RGB) camera. Conventional methods recover these parameters by extracting feature points from recorded video frames to guide the virtual camera. These methods fail when there is occlusion or motion blur in the recorded scene. In this paper, we propose a novel method (system) for pre-visualization and virtual-real image synthesis that overcomes the limitations of conventional methods. This system uses the spatial understanding principle of Microsoft HoloLens to perform the match-moving of virtual-real video scenes. Experimental results demonstrate that our system is much more accurate and efficient than existing systems for video compositing.

scholarly journals 3D Holographic Visualization for Pre-procedural Planning of Spatially Complex Brain Aneurysm Treatment

2020 ◽  
Author(s):  
Crew Joseph Weunski ◽  
Aydan Hanlon ◽  
Sara Al-Nimer ◽  
Jeffrey Yanof ◽  
Shazam Hussain
Keyword(s):  
Surgical Planning ◽  
Three Dimensional ◽  
Imaging Data ◽  
Brain Aneurysm ◽  
Volumetric Imaging ◽  
Planning Decisions ◽  
Spatial Understanding ◽  
Complex Anatomy ◽  
Procedural Planning ◽  
Microsoft Hololens

Abstract The purpose of this study was to develop and demonstrate a novel imaging platform that post-processes volumetric imaging data (e.g. Computed Tomography (CT) or Magnetic Resonance angiography) to provide holographic visualization for pre-procedural treatment planning of a morphologically complex brain aneurysm. Digital CT images were segmented, using the Materialise Mimics software, into three-dimensional digital models that were imported into a prototype application for the Microsoft HoloLens. Feedback from testing the prototype indicated potential for augmented reality to assist an interventionalist in spatial understanding and depth perception of spatially complex anatomy and could increase confidence in pre-procedural planning. Future studies will be conducted with additional cases to further validate the utility of the platform in surgical planning decisions and to expand the platform for patient/resident education, telemedicine, and intra-operative use.

scholarly journals CALCULATION OF THE ACHROMATIC DIFFRACTION SYSTEM WITH CORRECTED SPHERICAL ABERRATION (part 2)

2020 ◽  
Vol 8 (1) ◽  
pp. 127-133
Author(s):  
Yury Ts. Batomunkuev ◽  
Alexandra A. Pechenkina
Keyword(s):  
Spherical Aberration ◽  
Focal Length ◽  
Optical Element ◽  
Diffraction Order ◽  
Image Plane ◽  
Chromatic Aberration ◽  
Real Image ◽  
Optical Elements ◽  
A Value ◽  
Analytical Expressions

Achromatization of a three-component diffraction system consisting of one thick and two thin hologram optical elements is considered in the work. Analytical expressions are obtained for correcting the chromatic aberration of the position of a thick focusing hologram optical element by two scattering thin hologram optical elements in a given spectrum range. It is shown that achromatization is achieved for such a three-component system using two thin hologram elements located symmetrically on both sides of the thick element and having a value of the working diffraction order greater than the ratio of the focal length to the distance from the thin element to the image plane (at a given wavelength). The proposed three-component holographic system can be used to convert both an imaginary image into a real image and a real into an imaginary image in predetermined spectral regions of the visible, ultraviolet or infrared ranges of the spectrum.

scholarly journals Focus-Adjustable Head Mounted Display with Off-Axis System

2020 ◽  
Vol 10 (21) ◽  
pp. 7931
Author(s):  
So Hyun Seo ◽  
Jae Myung Ryu ◽  
Hojong Choi
Keyword(s):  
Optical System ◽  
Optical Axis ◽  
Focal Length ◽  
Normal Vector ◽  
Effective Focal Length ◽  
Head Mounted Display ◽  
Conventional Methods ◽  
Angle Of Reflection

An off-axis system refers to an optical system in which the optical axis and the normal vector at the vertex of each surface do not match. An off-axis optical system can be applied in order to construct a thin and light optical system. In particular, the optical system used for a see-through head-mounted display (HMD) must be designed asymmetrically, with respect to the optical axis. Because the vision of a human is different for each individual, HMD requires focus adjustment. The effective focal length (EFL) of the optical system must be calculated to obtain the focus adjustment. However, the off-axis optical system cannot be calculated by conventional methods. In this study, the EFL was calculated by rotating the coordinates of the rays near the optical axis by the angle of reflection or refraction at the intersection of each surface, with the rays coinciding with the optical axis. The magnitude of movement of the micro-display for focus adjustment was obtained from the calculated EFL, for a see-through type HMD.

scholarly journals Tracking Individual Targets for high Density Crowd Scenes Analysis

2020 ◽  
Author(s):  
Jack Norris ◽  
Wesley Creveling ◽  
Ernest Porter ◽  
Emory Vassel
Keyword(s):  
3D Model ◽  
Moving Objects ◽  
Focal Length ◽  
High Density ◽  
Block Matching ◽  
High Definition ◽  
Virtual Camera ◽  
Model Match ◽  
Block Motion ◽  
Spatio Temporal

In this paper we present a number of methods (manual, semi-automatic and automatic) for tracking individual targets in high density crowd scenes where thousand of people are gathered. The necessary data about the motion of individuals and a lot of other physical information can be extracted from consecutive image sequences in different ways, including optical flow and block motion estimation. One of the famous methods for tracking moving objects is the block matching method. This way to estimate subject motion requires the specification of a comparison window which determines the scale of the estimate.In this work we present a real-time method for pedestrian recognition and tracking in sequences of high resolution images obtained by a stationary (high definition) camera located in different places on the Haram mosque in Mecca. The objective is to estimate pedestrian velocities as a function of the local density.The resulting data of tracking moving pedestrians based on video sequences are presented in the following section. Through the evaluated system the spatio-temporal coordinates of each pedestrian during the Tawaf ritual are established. The pilgrim velocities as function of the local densities in the Mataf area (Haram Mosque Mecca) are illustrated and very precisely documented. Tracking in such places where pedestrian density reaches 7 to 8 Persons/m$^2$ is extremely challenging due to the small numberof pixels on the target, appearance ambiguity resulting from the dense packing, and severe inter-object occlusions. The tracking method which is outlined in this paper overcomes these challenges by using a virtual camera which is matched in position, rotation and focal length to the original camera in such a way that the features of the 3D-model match the feature position of the filmed mosque. In this model an individual feature has to be identified by eye, where contrast is a criterion. We do know that the pilgrims walk on a plane, and after matching the camera we also have the height of the plane in 3D-space from our 3D-model. A point object is placed at the position of a selected pedestrian. During the animation we set multiple animation-keys (approximately every 25 to 50 frames which equals 1 to 2 seconds) for the position, such that the position of the point and the pedestrian overlay nearly at every time.By combining all these variables with the available appearance information, we are able to track individual targets in high density crowds.

Resolution Attainable With the Present Day STEM

1973 ◽  
Vol 31 ◽  
pp. 230-231 ◽  
Author(s):  
J. S. Wall ◽  
J. P. Langmore ◽  
H. Isaacson ◽  
A. V. Crewe
Keyword(s):  
Spherical Aberration ◽  
Focal Length ◽  
Incident Beam ◽  
Scanning Transmission Electron Microscope ◽  
Aperture Size ◽  
Magnetic Lens ◽  
Peak Intensity ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Half Angle

The scanning transmission electron microscope (STEM) constructed by the authors employs a field emission gun and a 1.15 mm focal length magnetic lens to produce a probe on the specimen. The aperture size is chosen to allow one wavelength of spherical aberration at the edge of the objective aperture. Under these conditions the profile of the focused spot is expected to be similar to an Airy intensity distribution with the first zero at the same point but with a peak intensity 80 per cent of that which would be obtained If the lens had no aberration. This condition is attained when the half angle that the incident beam subtends at the specimen, 𝛂 = (4𝛌/Cs)¼

The Reduction of Chromatic Aberrations Due to Instrumental Instabilities

1971 ◽  
Vol 29 ◽  
pp. 14-15
Author(s):  
J. S. Lally ◽  
R. Evans
Keyword(s):  
Electron Microscope ◽  
High Voltage ◽  
Focal Length ◽  
Chromatic Aberration ◽  
Objective Lens ◽  
Usual Practice ◽  
Voltage Electron ◽  
Short Focal Length ◽  
Chromatic Aberrations ◽  
Electron Microscopes

One of the instrumental factors often limiting the resolution of the electron microscope is image defocussing due to changes in accelerating voltage or objective lens current. This factor is particularly important in high voltage electron microscopes both because of the higher voltages and lens currents required but also because of the inherently longer focal lengths, i.e. 6 mm in contrast to 1.5-2.2 mm for modern short focal length objectives.The usual practice in commercial electron microscopes is to design separately stabilized accelerating voltage and lens supplies. In this case chromatic aberration in the image is caused by the random and independent fluctuations of both the high voltage and objective lens current.

A Superconducting Microscope

1971 ◽  
Vol 29 ◽  
pp. 10-11 ◽  
Author(s):  
R. E. Worsham ◽  
J. E. Mann ◽  
E. G. Richardson
Keyword(s):  
Liquid Helium ◽  
Focal Length ◽  
Vacuum System ◽  
Objective Lens ◽  
Electrical Instability ◽  
Radiation Shields ◽  
And Control ◽  
Thermal Oscillations ◽  
Flux Pump

This superconducting microscope, Figure 1, was first operated in May, 1970. The column, which started life as a Siemens Elmiskop I, was modified by removing the objective and intermediate lenses, the specimen chamber, and the complete vacuum system. The large cryostat contains the objective lens and stage. They are attached to the bottom of the 7-liter helium vessel and are surrounded by two vapor-cooled radiation shields.In the initial operational period 5-mm and 2-mm focal length objective lens pole pieces were used giving magnification up to 45000X. Without a stigmator and precision ground pole pieces, a resolution of about 50-100Å was achieved. The boil-off rate of the liquid helium was reduced to 0.2-0.3ℓ/hour after elimination of thermal oscillations in the cryostat. The calculated boil-off was 0.2ℓ/hour. No effect caused by mechanical or electrical instability was found. Both 4.2°K and 1.7-1.9°K operation were routine. Flux pump excitation and control of the lens were quite smooth, simple, and, apparently highly stable. Alignment of the objective lens proved quite awkward, however, with the long-thin epoxy glass posts used for supporting the lens.

Improvements in the electron probe forming capabilities and x-ray hole counts in the Philips TEM

1983 ◽  
Vol 41 ◽  
pp. 376-377
Author(s):  
Richard L. McConville
Keyword(s):  
Field Strength ◽  
Electron Probe ◽  
Spherical Aberration ◽  
Focal Length ◽  
Objective Lens ◽  
Parallel Beam ◽  
Tilt Axis ◽  
X Ray ◽  
Small Probe ◽  
Specimen Height

A second generation twin lens has been developed. This symmetrical lens with a wider bore, yet superior values of chromatic and spherical aberration for a given focal length, retains both eucentric ± 60° tilt movement and 20°x ray detector take-off angle at 90° to the tilt axis. Adjust able tilt axis height, as well as specimen height, now ensures almost invariant objective lens strengths for both TEM (parallel beam conditions) and STEM or nano probe (focused small probe) modes.These modes are selected through use of an auxiliary lens situ ated above the objective. When this lens is on the specimen is illuminated with a parallel beam of electrons, and when it is off the specimen is illuminated with a focused probe of dimensions governed by the excitation of the condenser 1 lens. Thus TEM/STEM operation is controlled by a lens which is independent of the objective lens field strength.

Comparison of Deterministic and Linear Cosine Spatial Filtering of Transmission Electron Micrographs

1972 ◽  
Vol 30 ◽  
pp. 596-597
Author(s):  
David A. Ansley
Keyword(s):  
Spherical Aberration ◽  
Focal Length ◽  
Chromatic Aberration ◽  
Spatial Filter ◽  
Operating Conditions ◽  
Objective Lens ◽  
List Type ◽  
Spatial Filters ◽  
Transmission Electron ◽  
Wide Range

The coherence of the electron flux of a transmission electron microscope (TEM) limits the direct application of deconvolution techniques which have been used successfully on unmanned spacecraft programs. The theory assumes noncoherent illumination. Deconvolution of a TEM micrograph will, therefore, in general produce spurious detail rather than improved resolution.A primary goal of our research is to study the performance of several types of linear spatial filters as a function of specimen contrast, phase, and coherence. We have, therefore, developed a one-dimensional analysis and plotting program to simulate a wide 'range of operating conditions of the TEM, including adjustment of the:(1) Specimen amplitude, phase, and separation(2) Illumination wavelength, half-angle, and tilt(3) Objective lens focal length and aperture width(4) Spherical aberration, defocus, and chromatic aberration focus shift(5) Detector gamma, additive, and multiplicative noise constants(6) Type of spatial filter: linear cosine, linear sine, or deterministic

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