A low-complexity yet accurate calibration method for automotive augmented reality head-up displays

2021 ◽  
Author(s):  
Xiang Gao ◽  
Marc Necker ◽  
Wilhelm Stork
Keyword(s):  
Augmented Reality ◽  
Calibration Method ◽  
Low Complexity

Augmented Reality Overlay System for Computer-guided Needle Procedures

1969 ◽  
Author(s):  
Zachary Baum
Keyword(s):  
Augmented Reality ◽  
Real Time ◽  
Region Of Interest ◽  
Calibration Method ◽  
Position Error ◽  
Ct Image ◽  
Entire System ◽  
Projected Image ◽  
Needle Interventions

Purpose: Augmented reality overlay systems can be used to project a CT image directly onto a patient during procedures. They have been actively trialed for computer-guided procedures, however they have not become commonplace in practice due to restrictions of previous systems. Previous systems have not been handheld, and have had complicated calibration procedures. We put forward a handheld tablet-based system for assisting with needle interventions. Methods: The system consists of a tablet display and a 3-D printed reusable and customizable frame. A simple and accurate calibration method was designed to align the patient to the projected image. The entire system is tracked via camera, with respect to the patient, and the projected image is updated in real time as the system is moved around the region of interest. Results: The resulting system allowed for 0.99mm mean position error in the plane of the image, and a mean position error of 0.61mm out of the plane of the image. This accuracy was thought to be clinically acceptable for tool using computer-guidance in several procedures that involve musculoskeletal needle placements. Conclusion: Our calibration method was developed and tested using the designed handheld system. Our results illustrate the potential for the use of augmented reality handheld systems in computer-guided needle procedures. 

scholarly journals A low complexity digital frequency calibration with high jitter immunity for ultra-low-power oscillators

2019 ◽  
Vol 17 ◽  
pp. 145-150
Author(s):  
Markus Scholl ◽  
Ralf Wunderlich ◽  
Stefan Heinen
Keyword(s):  
Low Power ◽  
Communication Systems ◽  
Calibration Method ◽  
Low Complexity ◽  
Frequency Stability ◽  
Wireless Communication Systems ◽  
Ultra Low Power ◽  
Wireless Transceiver ◽  
Digital Frequency ◽  
Frequency Calibration

Abstract. This paper presents a highly efficient digital frequency calibration method for ultra-low-power oscillators in wireless communication systems. This calibration method locks the ultra-low-power oscillator's output frequency to the reference clock of the wireless transceiver during its send- and receive-state to achieve frequency stability over process variation and temperature drifts. The introduced calibration scheme offers high jitter immunity and short locking periods overcoming frequency calibration errors for typical ultra-low-power oscillator's by utilizing non-linear segmented feedback levels. In measurements the proposed calibration method improves the frequency stability of an ultra-low-power 32 kHz oscillator from 53 to 10 ppm ∘C−1 over a wide temperature range for temperature drifts of less than 1 ∘C s−1 with an estimated power consumption of 185 nW while coping with relocking periods of 7 ms.

A Low-Complexity Eyewear System for Direction-based Augmented Reality Applications

2017 ◽  
Author(s):  
Gabriele Miorandi ◽  
Davide Quaglia ◽  
Federico Fraccaroli ◽  
Walter Vendraminetto ◽  
Enrico Giordano ◽  
...  
Keyword(s):  
Augmented Reality ◽  
Low Complexity

A Low-Complexity I/Q Imbalance Calibration Method for Quadrature Modulator

2020 ◽  
Author(s):  
Jusung Kim ◽  
Han-Shin Jo ◽  
Kyoung-Jae Lee ◽  
Dong-Ho Lee ◽  
Dae-Hyun Choi ◽  
...  
Keyword(s):  
Calibration Method ◽  
Low Complexity ◽  
Quadrature Modulator

A hand-eye calibration method for augmented reality applied to computer-assisted orthopedic surgery

2018 ◽  
Vol 15 (2) ◽  
pp. e1969 ◽  
Author(s):  
Marcelo E. de Oliveira ◽  
Henrique G. Debarba ◽  
Alexandre Lädermann ◽  
Sylvain Chagué ◽  
Caecilia Charbonnier
Keyword(s):  
Augmented Reality ◽  
Orthopedic Surgery ◽  
Calibration Method ◽  
Computer Assisted ◽  
Computer Assisted Orthopedic Surgery

scholarly journals An Automatic Marker–Object Offset Calibration Method for Precise 3D Augmented Reality Registration in Industrial Applications

2019 ◽  
Vol 9 (20) ◽  
pp. 4464 ◽  
Author(s):  
Xuyue Yin ◽  
Xiumin Fan ◽  
Xu Yang ◽  
Shiguang Qiu ◽  
Zhinan Zhang
Keyword(s):  
Augmented Reality ◽  
Calibration Method ◽  
Industrial Applications ◽  
Target Object ◽  
Initial Position ◽  
Normal Direction ◽  
3D Image ◽  
3D Tracking ◽  
Registration Method ◽  
Calibration Tool

Industrial augmented reality (AR) applications demand high on the visual consistency of virtual-real registration. To present, the marker-based registration method is most popular because it is fast, robust, and convenient to obtain the registration matrix. In practice, the registration matrix should multiply an offset matrix that describes the transformation between the attaching position and the initial position of the marker relative to the object. However, the offset matrix is usually measured, calculated, and set manually, which is not accurate and convenient. This paper proposes an accurate and automatic marker–object offset matrix calibration method. First, the normal direction of the target object is obtained by searching and matching the top surface of the CAD model. Then, the spatial translation is estimated by aligning the projected and the imaged top surface. Finally, all six parameters of the offset matrix are iteratively optimized using a 3D image alignment framework. Experiments were performed on the publicity monocular rigid 3D tracking dataset and an automobile gearbox. The average translation and rotation errors of the optimized offset matrix are 2.10 mm and 1.56 degree respectively. The results validate that the proposed method is accurate and automatic, which contributes to a universal offset matrix calibration tool for marker-based industrial AR applications.

scholarly journals Generic precise augmented reality guiding system and its calibration method based on 3D virtual model

2016 ◽  
Vol 24 (11) ◽  
pp. 12026 ◽  
Author(s):  
Miao Liu ◽  
Shourui Yang ◽  
Zhangying Wang ◽  
Shujun Huang ◽  
Yue Liu ◽  
...  
Keyword(s):  
Augmented Reality ◽  
Calibration Method ◽  
Virtual Model ◽  
Guiding System

Single-Point Active Alignment Method (SPAAM) for Optical See-Through HMD Calibration for Augmented Reality

2002 ◽  
Vol 11 (3) ◽  
pp. 259-276 ◽  
Author(s):  
Mihran Tuceryan ◽  
Yakup Genc ◽  
Nassir Navab
Keyword(s):  
Augmented Reality ◽  
Single Point ◽  
User Interaction ◽  
Image Data ◽  
Calibration Method ◽  
Direct Access ◽  
Target Point ◽  
Additional Information ◽  
Single Target ◽  
The World

Augmented reality (AR) is a technology in which a user's view of the real world is enhanced or augmented with additional information generated from a computer model. To have a working AR system, the see-through display system must be calibrated so that the graphics are properly rendered. The optical see-through systems present an additional challenge because, unlike the video see-through systems, we do not have direct access to the image data to be used in various calibration procedures. This paper reports on a calibration method we developed for optical see-through headmounted displays. We first introduce a method for calibrating monocular optical seethrough displays (that is, a display for one eye only) and then extend it to stereo optical see-through displays in which the displays for both eyes are calibrated in a single procedure. The method integrates the measurements for the camera and a six-degrees-offreedom tracker that is attached to the camera to do the calibration. We have used both an off-the-shelf magnetic tracker as well as a vision-based infrared tracker we have built. In the monocular case, the calibration is based on the alignment of image points with a single 3D point in the world coordinate system from various viewpoints. In this method, the user interaction to perform the calibration is extremely easy compared to prior methods, and there is no requirement for keeping the head immobile while performing the calibration. In the stereo calibration case, the user aligns a stereoscopically fused 2D marker, which is perceived in depth, with a single target point in the world whose coordinates are known. As in the monocular case, there is no requirement that the user keep his or her head fixed.

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