Stereo Tracking System Research Articles

Joint Deep and Depth for Object-Level Segmentation and Stereo Tracking in Crowds

Tracking multiple people in crowds is a fundamental and essential task in the multimedia field. It is often hindered by difficulties, such as dynamic occlusion between objects, cluttered background, and abrupt illumination changes. To respond to this need, in this paper, we combine deep and depth to build a stereo tracking system for crowds. The core of the system is the fusion of the advantages of deep learning and depth information, which is exploited to achieve object segmentation and improve the multiobject tracking performance in severe occlusion. More specifically, first, to obtain more accurate detection observations in the tracking system, we present a novel object-level segmentation method. This method combines the effective detection results of deep learning with depth information to obtain precise object segmentation results. Then, we integrate the segmentation results and three-dimensional (3-D) information to extract 2-D and 3-D characteristics to represent the target, and design three similarity models to realize a stereo tracking method through data association in crowds. Finally, we build a diverse stereo dataset including various challenging indoor and outdoor scenes. The comprehensive experiments verify the effective and robust tracking performance of our system in various scenarios, and the system has rich output results including segmentation results, target distance, and tracking results. Moreover, the qualitative and quantitative comparison results show that the proposed algorithm not only has good object segmentation performance but also improves the tracking performance of completely and partially occluded objects, which is superior to the tested state-of-the-art tracking approaches.

Aerodynamic Coefficients of Free-Flying Cubes in Hypersonic Flowfield

Aerodynamic coefficients of a cube depending on a broad-range attitude change have been measured using the free-flight technique in a hypersonic flowfield. Experiments were performed therefore in the hypersonic wind tunnel H2K at the German Aerospace Center (DLR) in Cologne. The free-flight technique in H2K has allowed achieving a continuous rotation of the cube without any sting interferences in a broad angular range of 90°. This motion of the model during the free flight has been acquired using a nonintrusive high-speed stereo tracking system. A marker-based tracking algorithm has been applied to reconstruct the three-dimensional flight trajectories and attitudes to determine the resulting forces and moments. By using high-speed schlieren photography, the unsteady flow structures have been recorded. Pitch-angle-dependent aerodynamic coefficients of rotating cubes have been observed.

Real-Time Monocular Three-Dimensional Motion Tracking Using a Multithread Active Vision System

In this study, we developed a monocular stereo tracking system to be used as a marker-based, three-dimensional (3-D) motion capture system. This system aims to localize dozens of markers on multiple moving objects in real time by switching five hundred different views in 1 s. The ultrafast mirror-drive active vision used in our catadioptric stereo tracking system can accelerate a series of operations for multithread gaze control with video shooting, computation, and actuation within 2 ms. By switching between five hundred different views in 1 s, with real-time video processing for marker extraction, our system can function asJvirtual left and right pan-tilt tracking cameras, operating at 250/Jfps to simultaneously capture and processJpairs of 512 × 512 stereo images with different views via the catadioptric mirror system. We conducted several real-time 3-D motion experiments to capture multiple fast-moving objects with markers. The results demonstrated the effectiveness of our monocular 3-D motion tracking system.

Monocular Stereo Measurement Using High-Speed Catadioptric Tracking.

This paper presents a novel concept of real-time catadioptric stereo tracking using a single ultrafast mirror-drive pan-tilt active vision system that can simultaneously switch between hundreds of different views in a second. By accelerating video-shooting, computation, and actuation at the millisecond-granularity level for time-division multithreaded processing in ultrafast gaze control, the active vision system can function virtually as two or more tracking cameras with different views. It enables a single active vision system to act as virtual left and right pan-tilt cameras that can simultaneously shoot a pair of stereo images for the same object to be observed at arbitrary viewpoints by switching the direction of the mirrors of the active vision system frame by frame. We developed a monocular galvano-mirror-based stereo tracking system that can switch between 500 different views in a second, and it functions as a catadioptric active stereo with left and right pan-tilt tracking cameras that can virtually capture 8-bit color images each operating at 250 fps to mechanically track a fast-moving object with a sufficient parallax for accurate 3D measurement. Several tracking experiments for moving objects in 3D space are described to demonstrate the performance of our monocular stereo tracking system.

Fusion of freehand SPECT and ultrasound: First experience in preoperative localization of sentinel lymph nodes.

Radioguided sentinel lymph node biopsy (SLNB) is the standard of care in breast cancer and melanoma. Additional preoperative Single-photon emission computed tomography (SPECT/CT) for improved anatomical co-registration of the SLNs causes additional radiation exposure and is time-consuming and expensive. The aim of this prospective study was to evaluate a novel approach involving real-time fusion of freehand SPECT (fhSPECT) and ultrasound (US) for anatomical co-registration of SLNs. From February 2015 to February 2016, 153 patients were included in this prospective study. All patients underwent lymphoscintigraphy according to practical guidelines and 151 (118 cases of breast cancer, 30 cutaneous malignancies, and three cases of vulvar cancer) of the 153 patients were additionally investigated with fhSPECT-US. FhSPECT connected to a hand-held gamma detector generates three-dimensional images of the radioactivity distribution in the scanned area. For co-registration and real-time fusion of fhSPECT and subsequently performed US, an infrared stereo tracking system was used. In all patients an SLN was found on lymphoscintigraphy, and the fhSPECT detected corresponding hotspots in all but one patient. In 72% of patients and 73% of lymph node basins, real-time anatomical co-registration with US was feasible. The rate of success in achieving good co-registration increased from 60 to 75% after training by a radiologist specialized in breast imaging. A higher co-registration rate (78%) was observed in patients with only one SLN than in those with two SLNs (68%) or three or more SLNs (0%). Real-time fusion of fhSPECT and US for preoperative anatomical co-registration of SLNs is feasible. However, before this approach can completely replace preoperative lymphatic imaging, further technical developments are needed.

PRECISE HEAD TRACKING IN HEARING APPLICATIONS

Abstract. The paper gives an overview about two research projects, both dealing with optical head tracking in hearing applications. As part of the project “Development of a real-time low-cost tracking system for medical and audiological problems (ELCoT)” a cost-effective single camera 3D tracking system has been developed which enables the detection of arm and head movements of human patients. Amongst others, the measuring system is designed for a new hearing test (based on the “Mainzer Kindertisch”), which analyzes the directional hearing capabilities of children in cooperation with the research project ERKI (Evaluation of acoustic sound source localization for children). As part of the research project framework “Hearing in everyday life (HALLO)” a stereo tracking system is being used for analyzing the head movement of human patients during complex acoustic events. Together with the consideration of biosignals like skin conductance the speech comprehension and listening effort of persons with reduced hearing ability, especially in situations with background noise, is evaluated. For both projects the system design, accuracy aspects and results of practical tests are discussed.

Real-time stereo object tracking system by using block matching algorithm and optical binary phase extraction joint transform correlator

In this paper, we proposed a new adaptive stereo object tracking system that can control the convergence angle and pan/tilt of cameras by using optical binary phase extraction joint transform correlator and can extract the tracking object from a complex background and foreground noises by using the block-based mean square error algorithm. From the experimental results, the proposed stereo tracking system is found to track the object adaptively under the complex circumstances and changing background noises and the possibility of real-time implementation of the proposed system by using the optical system is also suggested.