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Tools used to evaluate the accuracy of spatial alignment of medical information: (a) plastic dummy head, (b) MicroScribe G2X digitizer, and (c) triangular prism for coordinate system calibration.
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Conventionally, the camera localization for augmented reality (AR) relies on detecting a known pattern within the captured images. In this study, a markerless AR scheme has been designed based on a Stereo Video See-Through Head-Mounted Display (HMD) device. The proposed markerless AR scheme can be utilized for medical applications such as training,...
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Citations
... Some authors decide not to use features and perform a direct evaluation of intensity changes between subsequent frames of the video [6][7][8]29]. Benefits of stereo cameras were explored in works of Park et al. [24] or Hsieh et al. [13]. SLAM algorithms based only on the visual data are prone to blurred images, caused especially by large rotational movements of the cameras. ...
Augmented reality applications provide new ways of presenting cultural heritage assets thanks to the recent advancement in the field of smart devices. Unfortunately, the construction of the hardware and lower computational power of mobile processors limit the potential of these applications. Namely, almost all current visual-inertial odometry libraries employed in smartphones require the real tracked objects to be close and contain distinguishable features, which is an issue when observing large virtual structures outdoors like historical buildings or objects on plain walls of halls or museums. This paper exploits the possibility of using the face cameras available in mobile devices for augmented reality tracking. It designs a prototype composed of iPhone and iPad devices and evaluates its contribution in two scenarios that current systems cannot handle. The results reveal the clear benefit of this approach for the cultural heritage, allowing it to operate in situations when users look up in the sky to see the roof of virtual buildings, or when they move closer to a white wall to perceive details of a virtual painting. In the end, the paper discusses the system’s limitations and proposes solutions to them.
... The OST display can be realized by using freeform optics [13,14], waveguide scheme [15][16][17], microstructure [18,19] and holographic optical element [20][21][22]. The other type of AR display is a video see-through (VST) display [23][24][25]. The VST display can digitally visualize computergenerated virtual information and pre-recorded real-world scenes by using a camera and it can be used for handheld and mobile devices. ...
We propose a high-performance reflection-type augmented reality (AR) 3D display by using a reflective polarizer (RP). The RP functions as a reflective imaging device as well as an image combiner that combines the real scenes and the 3D images reconstructed by the integral imaging display unit. Benefiting from the flawless imaging of the RP, the proposed reflection-type AR system can achieve high-definition 3D display. A prototype based on the proposed reflection-type AR structure is developed, and it presents good 3D display effects and reflection-type AR performances. The developed prototype is very compact, as thin as 3.4 mm, which makes it be a potential candidate in stomatology and vehicle AR display.
... Nonetheless, a higher average registration error was expected given that the face detection algorithm introduces an artificial noise, because it is based on a heuristic approach. In addition, lower average errors are registered when the study is compared with the marker-less video see-through AR system [57]; this could be due to the introduction of the integrated spatial understanding capabilities in the HoloLens display, which avoid the necessity to synchronize the display with a third device, an ad hoc synchronization that can lead to a higher overall measurement error. Further work is to be addressed in this direction, as the newer API provides simultaneous access to both RGB and depth images. ...
As of common routine in tumor resections, surgeons rely on local examinations of the removed tissues and on the swiftly made microscopy findings of the pathologist, which are based on intraoperatively taken tissue probes. This approach may imply an extended duration of the operation, increased effort for the medical staff, and longer occupancy of the operating room (OR). Mixed reality technologies, and particularly augmented reality, have already been applied in surgical scenarios with positive initial outcomes. Nonetheless, these methods have used manual or marker-based registration. In this work, we design an application for a marker-less registration of PET-CT information for a patient. The algorithm combines facial landmarks extracted from an RGB video stream, and the so-called Spatial-Mapping API provided by the HMD Microsoft HoloLens. The accuracy of the system is compared with a marker-based approach, and the opinions of field specialists have been collected during a demonstration. A survey based on the standard ISO-9241/110 has been designed for this purpose. The measurements show an average positioning error along the three axes of (x, y, z) = (3.3 ± 2.3, − 4.5 ± 2.9, − 9.3 ± 6.1) mm. Compared with the marker-based approach, this shows an increment of the positioning error of approx. 3 mm along two dimensions (x, y), which might be due to the absence of explicit markers. The application has been positively evaluated by the specialists; they have shown interest in continued further work and contributed to the development process with constructive criticism.
... There are two approaches to merge real world scenes with virtual images in an AR display. One is a video see-through AR display, which captures real world scenes using a camera and displays them together with computer-generated virtual images on a display device [3,4]. The other is an optical see-through AR display, which permits observers to directly perceive the physical real world through a transparent image combiner [5][6][7][8][9]. ...
An augmented reality (AR) three-dimensional (3D) display based on one-dimensional integral imaging (1DII), by using a lenticular lens array holographic optical element (LLA-HOE), is proposed. The 3D image of the 1DII has higher vertical resolution compared with the image of conventional integral imaging whose resolution is sharply reduced for providing quasi-continuous viewpoints in both the horizontal and vertical directions. The proposed 3D display consists of a projector and an LLA-HOE and is compact. As an image combiner, the LLA-HOE can diffract Bragg-matched light rays that have the same wavelength and incident angle as the original reference wave; it can also function as a lenticular lens array to reconstruct a 3D image but transmit other light rays emitted from the surroundings. In the experiment, an LLA-HOE of 80 mm × 80 mm size is recorded, and a combination of a high-resolution 3D virtual image and a real 3D object is presented by the proposed AR 3D display.
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The article describes the comparison and analysis of five 3D models of the hunting tool from the Ljubljanica River found near Sinja Gorica. The 40,000 years old Palaeolithic point, discovered by underwater archaeologists during a preventive archeological survey, was made out of yew wood. Five 3D models of the point were taken over the period of ten years, two before and three after the conservation process. The comparison of the 3D models serves two purposes. The primary goal is to evaluate the changes of the artifact that occurred during this period and, specifically, to compare its shape before and after the
treatment. Conservation of waterlogged wood is still a delicate and somewhat uncertain process in regards to the long term survivability of such artifacts. The second goal is to asses which software tools are currently available for such comparison, what
are technical problems that need to be addressed, and how to effectively present or visualize the sometimes small but critical changes of shape.
... These methods usually involve marker-based (external fiducial markers), featurebased (internal anatomical landmarks) or intensity-based methods that find a geometric transformation that brings the projection of a 3D image into the best possible spatial correspondence with the 2D images by optimizing a registration criterion. [75] Veins Localization Optical Vuzix STAR 1200XL(modified) Manually Aligned Chang et al (2015) [76] Remote Surgical Assistance Video VUNIX iWear VR920 Optical Tracker + KLT * Hsieh et al (2015) [77] Head CT Visulization Video Vuzix Wrap 1200DXAR KLT + ICP ** Wang et al (2015) [78] Screw Placement Navigation Optical NVIS nVisor ST60 Optical Tracker Vigh et al (2014) [79] Oral Implantology Video NVIS nVisor SX60 Optical Tracker Hu et al (2013) [80] Surgery Guidance Video eMagin Z800 3D Visor Marker Abe et al (2013) [81] Percutaneous Vertebroplasty Video HMD by Epson (Model Unknow) Marker Azimi et al (2012) [82] Navigation in Neurosurgery Optical Goggles by Juxtopia Marker Blum et al (2012) [83] Anatomy Visulization Video Not Mentioned Gaze-tracker Toshiaki (2010) [84] Cognitive Poststroke-Patient Rehabilitation Video VUNIX iWear VR920 Marker * Kanade-Lucas-Tomasi algorithm [88]. ** Iterative Closest Point algorithm [89]. ...
Mixed Reality (MR) is of increasing interest within technology-driven modern medicine but is not yet used in everyday practice. This situation is changing rapidly, however, and this paper explores the emergence of MR technology and the importance of its utility within medical applications. A classification of medical MR has been obtained by applying an unbiased text mining method to a database of 1,403 relevant research papers published over the last two decades. The classification results reveal a taxonomy for the development of medical MR research during this period as well as suggesting future trends. We then use the classification to analyse the technology and applications developed in the last five years. Our objective is to aid researchers to focus on the areas where technology advancements in medical MR are most needed, as well as providing medical practitioners with a useful source of reference.
GaN-based Micro-LED has become a research hotspot as a novel display technology due to its numerous unique advantages. Especially in augmented reality and smart glasses applications, Micro-LED display chip with high transparency possesses unparalleled opportunities. In this work, GaN-based transparent single-color Micro-LED display chip based on double-side polished sapphire substrate was designed with a single pixel size of
$20\,\,\mu \text{m}\times 20\,\,\mu \text{m}$
, and a resolution of 254 pixel per inch (PPI). The transparency reaches 80% among the whole display area ~ 0.18 inch, and the luminance of display chip can reach up to 25000 nits. It demonstrates a broad application prospects in augmented reality, smart glasses, and etc., providing promising vista for the development of “Metaverse” in the future.
In this paper, we propose an augmented reality (AR) autostereoscopic three-dimensional (3D) display based on sparse reflection array (SRA). The proposed display consists of a transparent light-emitting diode (LED) display panel and a periodic SRA. Benefiting from the advantages that most areas of the LED display panel are transparent and the arrangement of the SRA is periodic, the proposed display can realize a good fusion of real 3D objects and virtual 3D images. In addition, the proposed display has a higher light transmittance of the real-world object than the traditional parallax barrier based autostereoscopic 3D display and has a thinner thickness than the traditional lenticular lens barrier based autostereoscopic 3D display. An optical experiment of the proposed display is developed, and the experimental results show that the proposed display has a better display performance compared with the conventional AR autostereoscopic 3D display. Moreover, the proposed display is simple, which is more conducive to achieving practical applications in large-scene AR exhibition systems, glass curtain walls, and outdoor advertisements.
