scholarly journals An Augmented Reality System Using Improved-Iterative Closest Point Algorithm for On-Patient Medical Image Visualization

Sensors ◽  
2018 ◽  
Vol 18 (8) ◽  
pp. 2505 ◽  
Author(s):  
Ming-Long Wu ◽  
Jong-Chih Chien ◽  
Chieh-Tsai Wu ◽  
Jiann-Der Lee
Keyword(s):  
Augmented Reality ◽  
Perturbation Technique ◽  
Optimal Solution ◽  
Reference Points ◽  
Iterative Closest Point ◽  
Alignment Algorithm ◽  
Alignment Method ◽  
Surface Information ◽  
Head Mounted Display ◽  
Head Surface

In many surgery assistance systems, cumbersome equipment or complicated algorithms are often introduced to build the whole system. To build a system without cumbersome equipment or complicated algorithms, and to provide physicians the ability to observe the location of the lesion in the course of surgery, an augmented reality approach using an improved alignment method to image-guided surgery (IGS) is proposed. The system uses RGB-Depth sensor in conjunction with the Point Cloud Library (PCL) to build and establish the patient’s head surface information, and, through the use of the improved alignment algorithm proposed in this study, the preoperative medical imaging information obtained can be placed in the same world-coordinates system as the patient’s head surface information. The traditional alignment method, Iterative Closest Point (ICP), has the disadvantage that an ill-chosen starting position will result only in a locally optimal solution. The proposed improved para-alignment algorithm, named improved-ICP (I-ICP), uses a stochastic perturbation technique to escape from locally optimal solutions and reach the globally optimal solution. After the alignment, the results will be merged and displayed using Microsoft’s HoloLens Head-Mounted Display (HMD), and allows the surgeon to view the patient’s head at the same time as the patient’s medical images. In this study, experiments were performed using spatial reference points with known positions. The experimental results show that the proposed improved alignment algorithm has errors bounded within 3 mm, which is highly accurate.

scholarly journals Improving a Rapid Alignment Method of Tomography Projections by a Parallel Approach

2021 ◽  
Vol 11 (16) ◽  
pp. 7598
Author(s):  
Francesco Guzzi ◽  
George Kourousias ◽  
Alessandra Gianoncelli ◽  
Lorella Pascolo ◽  
Andrea Sorrentino ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
High Resolution ◽  
Real World ◽  
Reference Points ◽  
Alignment Algorithm ◽  
High Contrast ◽  
Alignment Method ◽  
Automatic Methods ◽  
The Cost ◽  
Resolution Dataset

The high resolution of synchrotron cryo-nano tomography can be easily undermined by setup instabilities and sample stage deficiencies such as runout or backlash. At the cost of limiting the sample visibility, especially in the case of bio-specimens, high contrast nano-beads are often added to the solution to provide a set of landmarks for a manual alignment. However, the spatial distribution of these reference points within the sample is difficult to control, resulting in many datasets without a sufficient amount of such critical features for tracking. Fast automatic methods based on tomography consistency are thus desirable, especially for biological samples, where regular, high contrast features can be scarce. Current off-the-shelf implementations of such classes of algorithms are slow if used on a real-world high-resolution dataset. In this paper, we present a fast implementation of a consistency-based alignment algorithm especially tailored to a multi-GPU system. Our implementation is released as open-source.

Augmented Reality Procedure Assistance System for Operator Training and Simulation

2020 ◽  
Vol 64 (1) ◽  
pp. 1176-1180
Author(s):  
Eugene Hayden ◽  
Kang Wang ◽  
Chengjie Wu ◽  
Shi Cao
Keyword(s):  
Augmented Reality ◽  
Situation Awareness ◽  
Mental Workload ◽  
Field Of View ◽  
Task Completion ◽  
Operator Training ◽  
Head Mounted Display ◽  
Subject Design ◽  
Procedural Tasks ◽  
Speed Accuracy

This study explores the design, implementation, and evaluation of an Augmented Reality (AR) prototype that assists novice operators in performing procedural tasks in simulator environments. The prototype uses an optical see-through head-mounted display (OST HMD) in conjunction with a simulator display to supplement sequences of interactive visual and attention-guiding cues to the operator’s field of view. We used a 2x2 within-subject design to test two conditions: with/without AR-cues, each condition had a voice assistant and two procedural tasks (preflight and landing). An experiment examined twenty-six novice operators. The results demonstrated that augmented reality had benefits in terms of improved situation awareness and accuracy, however, it yielded longer task completion time by creating a speed-accuracy trade-off effect in favour of accuracy. No significant effect on mental workload is found. The results suggest that augmented reality systems have the potential to be used by a wider audience of operators.

scholarly journals Fooling the size–weight illusion—Using augmented reality to eliminate the effect of size on perceptions of heaviness and sensorimotor prediction

2021 ◽  
Author(s):  
Nina Rohrbach ◽  
Joachim Hermsdörfer ◽  
Lisa-Marie Huber ◽  
Annika Thierfelder ◽  
Gavin Buckingham
Keyword(s):  
Augmented Reality ◽  
Visual Cues ◽  
Equal Mass ◽  
Small Object ◽  
Verbal Reports ◽  
Fully Integrated ◽  
Head Mounted Display ◽  
Lift Off ◽  
Cognitive Knowledge ◽  
Weight Illusion

AbstractAugmented reality, whereby computer-generated images are overlaid onto the physical environment, is becoming significant part of the world of education and training. Little is known, however, about how these external images are treated by the sensorimotor system of the user – are they fully integrated into the external environmental cues, or largely ignored by low-level perceptual and motor processes? Here, we examined this question in the context of the size–weight illusion (SWI). Thirty-two participants repeatedly lifted and reported the heaviness of two cubes of unequal volume but equal mass in alternation. Half of the participants saw semi-transparent equally sized holographic cubes superimposed onto the physical cubes through a head-mounted display. Fingertip force rates were measured prior to lift-off to determine how the holograms influenced sensorimotor prediction, while verbal reports of heaviness after each lift indicated how the holographic size cues influenced the SWI. As expected, participants who lifted without augmented visual cues lifted the large object at a higher rate of force than the small object on early lifts and experienced a robust SWI across all trials. In contrast, participants who lifted the (apparently equal-sized) augmented cubes used similar force rates for each object. Furthermore, they experienced no SWI during the first lifts of the objects, with a SWI developing over repeated trials. These results indicate that holographic cues initially dominate physical cues and cognitive knowledge, but are dismissed when conflicting with cues from other senses.

An Improved Initial Alignment Method of Strap-Down Inertial Navigation System on a Swaying Base

2013 ◽  
Vol 415 ◽  
pp. 143-148
Author(s):  
Li Hua Zhu ◽  
Xiang Hong Cheng
Keyword(s):  
Navigation System ◽  
Inertial Navigation System ◽  
Alignment Algorithm ◽  
Alignment Method ◽  
Initial Alignment ◽  
Vehicle Simulation ◽  
Robust Property ◽  
Simulation Results ◽  
Lever Arm Effect ◽  
The Impact

The design of an improved alignment method of SINS on a swaying base is presented in this paper. FIR filter is taken to decrease the impact caused by the lever arm effect. And the system also encompasses the online estimation of gyroscopes’ drift with Kalman filter in order to do the compensation, and the inertial freezing alignment algorithm which helps to resolve the attitude matrix with respect to its fast and robust property to provide the mathematical platform for the vehicle. Simulation results show that the proposed method is efficient for the initial alignment of the swaying base navigation system.

Visual Coherence in Mixed Reality: A Systematic Enquiry

2017 ◽  
Vol 26 (1) ◽  
pp. 16-41 ◽  
Author(s):  
Jonny Collins ◽  
Holger Regenbrecht ◽  
Tobias Langlotz
Keyword(s):  
Augmented Reality ◽  
Mixed Reality ◽  
Focus Of Attention ◽  
User Experiences ◽  
Head Mounted Display ◽  
Virtual And Augmented Reality

Virtual and augmented reality, and other forms of mixed reality (MR), have become a focus of attention for companies and researchers. Before they can become successful in the market and in society, those MR systems must be able to deliver a convincing, novel experience for the users. By definition, the experience of mixed reality relies on the perceptually successful blending of reality and virtuality. Any MR system has to provide a sensory, in particular visually coherent, set of stimuli. Therefore, issues with visual coherence, that is, a discontinued experience of a MR environment, must be avoided. While it is very easy for a user to detect issues with visual coherence, it is very difficult to design and implement a system for coherence. This article presents a framework and exemplary implementation of a systematic enquiry into issues with visual coherence and possible solutions to address those issues. The focus is set on head-mounted display-based systems, notwithstanding its applicability to other types of MR systems. Our framework, together with a systematic discussion of tangible issues and solutions for visual coherence, aims at guiding developers of mixed reality systems for better and more effective user experiences.

scholarly journals Percutaneous placement of lumbar pedicle screws via intraoperative CT image–based augmented reality–guided technology

2020 ◽  
Vol 32 (4) ◽  
pp. 542-547 ◽  
Author(s):  
Huan Liu ◽  
Junlong Wu ◽  
Yu Tang ◽  
Haiyin Li ◽  
Wenkai Wang ◽  
...  
Keyword(s):  
Augmented Reality ◽  
Pedicle Screw ◽  
Pedicle Screws ◽  
Clinical Situation ◽  
Ct Image ◽  
Alignment Method ◽  
Intraoperative Ct ◽  
Screw Perforation ◽  
Automatic Alignment ◽  
Lumbar Pedicle

OBJECTIVEThe authors aimed to assess, in a bone-agar experimental setting, the feasibility and accuracy of percutaneous lumbar pedicle screw placements using an intraoperative CT image–based augmented reality (AR)–guided method compared to placements using a radiograph-guided method. They also compared two AR hologram alignment methods.METHODSTwelve lumbar spine sawbones were completely embedded in hardened opaque agar, and a cubic marker was fixed on each phantom. After intraoperative CT, a 3D model of each phantom was generated, and a specialized application was deployed into an AR headset (Microsoft HoloLens). One hundred twenty pedicle screws, simulated by Kirschner wires (K-wires), were placed by two experienced surgeons, who each placed a total of 60 screws: 20 placed with a radiograph-guided technique, 20 with an AR technique in which the hologram was manually aligned, and 20 with an AR technique in which the hologram was automatically aligned. For each K-wire, the insertion path was expanded to a 6.5-mm diameter to simulate a lumbar pedicle screw. CT imaging of each phantom was performed after all K-wire placements, and the operative time required for each K-wire placement was recorded. An independent radiologist rated all images of K-wire placements. Outcomes were classified as grade I (no pedicle perforation), grade II (screw perforation of the cortex by up to 2 mm), or grade III (screw perforation of the cortex by > 2 mm). In a clinical situation, placements scored as grade I or II would be acceptable and safe for patients.RESULTSAmong all screw placements, 75 (94%) of 80 AR-guided placements and 40 (100%) of 40 radiograph-guided placements were acceptable (i.e., grade I or II; p = 0.106). Radiograph-guided placements had more grade I outcomes than the AR-guided method (p < 0.0001). The accuracy of the two AR alignment methods (p = 0.526) was not statistically significantly different, and neither was it different between the AR and radiograph groups (p < 0.0001). AR-guided placements required less time than the radiograph-guided placements (mean ± standard deviation, 131.76 ± 24.57 vs 181.43 ± 15.82 seconds, p < 0.0001). Placements performed using the automatic-alignment method required less time than those using the manual-alignment method (124.20 ± 23.80 vs 139.33 ± 23.21 seconds, p = 0.0081).CONCLUSIONSIn bone-agar experimental settings, AR-guided percutaneous lumbar pedicle screw placements were acceptable and more efficient than radiograph-guided placements. In a comparison of the two AR-guided placements, the automatic-alignment method was as accurate as the manual method but more efficient. Because of some limitations, the AR-guided system cannot be recommended in a clinical setting until there is significant improvement of this technology.

scholarly journals OUTDOOR AR-APPLICATION FOR THE DIGITAL MAP TABLE

2020 ◽  
Vol XLIV-3/W1-2020 ◽  
pp. 93-98
Author(s):  
S. Maier ◽  
T. Gostner ◽  
F. van de Camp ◽  
A. H. Hoppe
Keyword(s):  
Augmented Reality ◽  
Geographical Location ◽  
Satellite System ◽  
Reference Points ◽  
Sensor Data ◽  
Measurement Unit ◽  
Positional Accuracy ◽  
Digital Map ◽  
The World ◽  
Global Navigation Satellite

Abstract. In many fields today, it is necessary that a team has to do operational planning for a precise geographical location. Examples for this are staff work, the preparation of surveillance tasks at major events or state visits and sensor deployment planning for military and civil reconnaissance. For these purposes, Fraunhofer IOSB is developing the Digital Map Table (DigLT). When making important decisions, it is often helpful or even necessary to assess a situation on site. An augmented reality (AR) solution could be useful for this assessment. For the visualization of markers at specific geographical coordinates in augmented reality, a smartphone has to be aware of its position relative to the world. It is using the sensor data of the camera and inertial measurement unit (IMU) for AR while determining its absolute location and direction with the Global Navigation Satellite System (GNSS) and its magnetic compass. To validate the positional accuracy of AR markers, we investigated the current state of the art and existing solutions. A prototype application has been developed and connected to the DigLT. With this application, it is possible to place markers at geographical coordinates that will show up at the correct location in augmented reality at anyplace in the world. Additionally, a function was implemented that lets the user select a point from the environment in augmented reality, whose geographical coordinates are sent to the DigLT. The accuracy and practicality of the placement of markers were examined using geodetic reference points. As a result, we can conclude that it is possible to mark larger objects like a car or a house, but the accuracy mainly depends on the internal compass, which causes a rotational error that increases with the distance to the target.

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