Detection Rate Of Markers Research Articles

An Adaptive Radon-Transform-Based Marker Detection and Localization Method for Displacement Measurements Using Unmanned Aerial Vehicles.

UAVs have been widely used in deformation monitoring because of their high availability and flexibility. However, the quality of UAV images is affected by changing attitude and surveying environments, resulting in a low monitoring accuracy. Cross-shaped markers are used to improve the accuracy of UAV monitoring due to their distinct center contrast and absence of eccentricity. However, existing methods cannot rapidly and precisely detect these markers in UAV images. To address these problems, this paper proposes an adaptive Radon-transform-based marker detection and localization method for UAV displacement measurements, focusing on two critical detection parameters, namely, the radius of marker information acquisition and the edge width of the cross-shaped scoring template. The experimental results show that the marker detection rate is 97.2% under different combinations of flight altitudes, radius ratios of marker information acquisition, and marker sizes. Furthermore, the root mean square error of detection and localization is 0.57 pixels, significantly surpassing the performance and accuracy of other methods. We also derive the critical detection radius and appropriate parameter combinations for different heights to further improve the practicality of the method.

Performance Evaluation of Fiducial Marker-Based Pose Estimation for Relative Localization of Agricultural Tractor and Implement

Highlights 3D pose estimation using a typical webcam and a fiducial marker could be implemented to accurately localize the relative pose of an agricultural implement with respect to a tractor at a short camera-marker distance of around 1 m. The marker-based localization could aid in the positioning of a proper hitching pose for autonomous implement hitching. Camera exposure needs to be tuned for the detection of a marker with both light and dark on the marker plane. Abstract. Computer vision using a typical webcam and a fiducial marker was established for localizing an implement with respect to a tractor in the context of an autonomous hitching operation. Bench tests and the tractor-implement hitching tests were conducted with different camera-marker center offsets, camera exposures, and outdoor lighting conditions to estimate the marker pose in the camera frame and compare it to the ground truth of the corresponding offsets. The results of the bench tests demonstrated that the computer vision robustly detected the marker at 1m camera-marker distance, achieving a 100% marker detection rate. It also accurately estimated both translations and rotations of the marker pose with RMSE less than 6 mm and 1°, respectively. Furthermore, the marker-based positioning provided accurate implement localization with an average absolute error of 6.4 mm and 0.6° under all tested lighting conditions and could be used to aid in the localization of proper implement hitching poses. Keywords: 3D pose estimation, Accuracy, Detection rate, Fiducial marker, Typical webcam.

Possibilities of a biobank for serological monitoring of infectious morbidity

Currently, monitoring infectious morbidity, control and forecasting the epidemic process is a topical health problem.Aim. To analyze the capabilities of the biobank for serological monitoring of infectious diseases using the Epstein- Barr virus (EBV), which is associated with infectious mononucleosis, as well as somatic pathology, including cancer.Material and methods. Using the quantitative enzyme- linked immunosorbent assay for specific antibodies to various EBV proteins, we studied blood serum samples from healthy individuals (2010, 2016, 2019, 2020, 2021 and 2022) from the collection of the N. F. Gamaleya National Center of Epidemiology and Microbiology.Results. For the first time, the intensity of EBV epidemic process among apparently healthy adult residents of the capital was assessed using samples of biological material and a biobank information database. At the time of examination, 0,8% of individuals were not infected with EBV, and 9,4% suffered reactivation of a chronic infection. There were no significant changes in detection rate of markers over the years.Conclusion. Certified collections of blood sera can be effectively used to study population immunity, the prevalence of individual infections, population protection nationwide, etc.

Application of ultrasound-guided placement of markers for locating axillary lymph nodes of breast cancer.

With the continuous improvement of pathological complete response (pCR) rate after neoadjuvant therapy (NAT), it is necessary to locate the tumor bed and axillary lymph nodes (ALNs) for subsequent surgery. Therefore, breast tissue markers emerge. This study aims to evaluate the feasibility and accuracy of ultrasound (US)-guided placement of markers for locating ALNs of breast cancer. A total of 285 patients who received US-guided placement of markers for locating ALNs in our hospital were selected. Among these patients, 87 patients were in the early breast cancer (EBC) group with negative ALNs and 198 ones were in the NAT group with positive ALNs. Data including the basic information of patients, position and size of ALN, process of US-guided marker placement, placement success rate, complications, detection rate of marker by imaging, and shift rate were recorded. All patients were successfully undergone US-guided marker placement. And the average operation time was 2 minutes with no adverse reactions. All the patients underwent surgery successfully. US, computer tomography (CT) and magnetic resonance imaging (MRI) were used to detect the marker. The detection rate of markers by US and CT/MRI were 100% (87/87) in EBC group, and 98.5% (195/198) and 100% (198/198) by US and CT/MRI, respectively, in NAT group. The postoperative marker shift rate was 2.1% (6/285), including 3.4% (3/87) marker shift rate in EBC group and 1.5% (3/198) in NAT group, with no statistically significant difference between them. US-guided marker placement in ALNs of breast cancer is simple and safe, with firm positioning and low shift rate, which is convenient for clinical promotion.

Aerial Imaging by Retro-Reflection for Mid-Air Image Display and Camera Viewpoint Transfer

Previously, a telepresence system, called Levitar, was proposed to allow communication through computer-graphics (CG) avatars in real space. Levitar employs micro-mirror array plates (MMAPs) to display mid-air images and optically transfer the camera viewpoint to the mid-air image-display position optically. This system captures the first-person view of a mid-air image avatar; however, it has a limitation that the stray light caused by MMAPs reduces its range. Therefore, in this study, we propose an optical system to capture a wider range of mid-air viewpoints. The proposed optical system uses aerial imaging by retro-reflection (AIRR) instead of MMAPs for mid-air image display and camera viewpoint transfer. AIRR is a mid-air imaging system that includes a beam splitter and retro-reflector. However, in contrast to MMAPs, it does not generate stray light. The optical transfer of the camera viewpoint by AIRR enables the capture of a large area. To evaluate the range of the capturing area when using cameras with MMAPs and AIRR, we conducted experiments under different camera gaze directions and effective angle of view. The results indicate that AIRR maintains a constant resolution up to 40° of the camera gaze direction, whereas MMAPs have a lower resolution above 30°, and the area of the marker detection rate of over 80% is approximately 54% larger for AIRR than for MMAPs. This implies that AIRR achieved a wider imaging range than MMAPs for mid-air telepresence systems.

Marker-Based Structural Displacement Measurement Models with Camera Movement Error Correction Using Image Matching and Anomaly Detection.

To prevent collapse accidents at construction sites, the marker-based displacement measurement method was developed. However, it has difficulty in obtaining accurate measurements at long distances (>50 m) in an outdoor environment because of camera movements. To overcome this problem, marker-based structural displacement measurement models using image matching and anomaly detection were designed in this study. Then, the performance of each model in terms of camera movement error correction was verified through comparison with that of a conventional model. The results show that the systematic errors due to camera movements (<1.7°) were corrected. The detection rate of markers with displacement reached 95%, and the probability that the error size would be less than 10 mm was ≥ 95% with a 95% confidence interval at a distance of more than 100 m. Moreover, the normalized mean square error was less than 0.1. The models developed in this study can measure the pure displacement of an object without the systematic errors caused by camera movements. Furthermore, these models can be used to measure the displacements of distant structures using closed-circuit television cameras and markers in an outdoor environment with high accuracy.

Impact of current approaches to laboratory screening of donated blood and its components on hepatitis B virus infection in patients with blood system diseases

To evaluate the detection rate of markers for hepatitis B virus (HBV) in the blood samples taken from patients with blood system diseases, by applying the current approaches to examining donated blood and its components for markers of viral infections. The investigation included blood samples from patients with blood system diseases (n=364) and donors (n=5,011). The results of laboratory screening of donated blood samples (n=13,081) were retrospectively analyzed. Commercial kits of reagents were used for immunochemical assay and polymerase chain reaction. Patients with blood system diseases were recorded to have markers of active HBV infection in 12.6% of cases, anti-HBc in 31.3%, and anti-HBs in 37.6%. A retrospective analysis of the results of screening donated blood samples showed the presence of markers for active HBV infection in 0.28% of cases. A prospective examination of blood donors revealed markers of HBV infection in 4.83% of cases, including those of active forms in 0.54% and anti-HBc in 4.79%. The markers of active HBV infection in donors were only anti-HBc IgM in 0.42% of cases. The blood samples from donors with an anti-HBs titer of >200 mIU/ml contained anti-HBc IgM in 10.5%. In the last 5-7 years, the detection rate of markers of HBV infection in the blood samples of patients with blood system diseases have remained at a high level. Screening for decreed markers fails to identify people with inapparent infections among the donors. Even high anti-HBs concentrations in the donated blood may be a risk for HBV transmission by transfusion to a recipient.

An In Vitro Study of a New Device: Evaluation of Novel Wide-Angle Lens Flexible Cystoscope Using Phantom Bladder Model.

The features and usefulness of a novel wide-angle lens flexible cystoscope were assessed with a view to its practical application. A phantom bladder model, on which a total of 12 markers that resemble lesions were arranged, was created for this study. Twenty-six urologists at three institutions observed this phantom bladder model using a conventional flexible cystoscope and a novel wide-angle lens flexible cystoscope, and they compared the observation time, marker detection rate, number of misidentified marker locations, overlooked locations, and misidentified location sites of both devices. Specific observation procedures that make use of the features of a wide-angle lens flexible cystoscope were also investigated. The observation time tended to be shorter with the wide-angle lens cystoscope than with a conventional cystoscope (104.9 seconds vs 113.6 seconds, p = 0.123). The marker detection rate was higher with the wide-angle lens cystoscope (90.2% vs 85.1%, p = 0.005). The number of marker location misidentifications did not differ between the two devices. Using a specifically designed observation procedure with the wide-angle lens cystoscope tended to further improve the marker detection rate (91.4% vs 88.1%, p = 0.157). Compared with a conventional cystoscope, a wide-angle lens cystoscope improved the lesion detection rate and has the potential to reduce observation time. The novel wide-angle lens flexible cystoscope is regarded as a useful device that offers advantages not available with a conventional cystoscope.