Refine
Document Type
- Conference Proceeding (6)
- Article (reviewed) (3)
- Doctoral Thesis (1)
Conference Type
- Konferenzartikel (5)
- Konferenz-Poster (1)
Is part of the Bibliography
- yes (10)
Keywords
- Erweitere Realität (1)
- Kalibrieren (1)
- Kalibrierung (1)
- Kamera (1)
- Open Source (1)
- Optik (1)
- TinyOS (1)
- Tk (1)
- Wireless M-Bus (1)
- model driven design (1)
Open Access
- Closed Access (6)
- Bronze (1)
- Closed (1)
- Open Access (1)
This work describes a camera-based method for the calibration of optical See-Through Glasses (STGs). A new calibration technique is introduced for calibrating every single display pixel of the STGs in order to overcome the disadvantages of a parametric model. A non-parametric model compared to the parametric one has the advantage that it can also map arbitrary distortions. The new generation of STGs using waveguide-based displays [5] will have higher arbitrary distortions due to the characteristics of their optics. First tests show better accuracies than in previous works. By using cameras which are placed behind the displays of the STGs, no error prone user interaction is necessary. It is shown that a high accuracy tracking device is not necessary for a good calibration. A camera mounted rigidly on the STGs is used to find the relations between the system components. Furthermore, this work elaborates on the necessity of a second subsequent calibration step which adapts the STGs to a specific user. First tests prove the theory that this subsequent step is necessary.
This work describes a non-parametric camera-based method for the calibration of Optical See-Through Glasses (OSTG). Existing works model the optical system through perspective projection and parametric functions. In the border areas of the displays such models are often inadequate. Moreover, rigid calibration patterns, that produce only a small amount of non-equidistant point correspondences, are used. In order to overcome these disadvantages every single display pixel is calibrated individually. The error prone user interaction is avoided by using cameras placed behind the displays of the OSTG. The displays show a shifting pattern that is used to calculate the pixels' locations. A camera mounted rigidly on the OSTG is used to find the relations between the system components. The obtained results show better accuracies than in previous works and prove that a second calibration step for user adaptation is necessary for high accuracy applications.
Die Verwendung von Kameras als Messmittel für medizinische Anwendungen setzt deren präzise Kalibrierung voraus. Gängige Verfahren modellieren die Abbildungseigenschaften einer Kamera mittels perspektivischer Projektion und parametrisierter Funktionen zur Beschreibung von Linsenverzerrung. In den Randbereichen des Kamerabildes sind diese Modelle oft unzureichend. Außerdem bedingt die Verwendung starrer Kalibriermuster eine in der Regel kleine Anzahl an nicht gleichmäßig verteilten Punktkorrespondenzen zur Bestimmung der Modellparameter. In der vorliegenden Arbeit wird ein vollkommen neues und nicht auf Modellen basierendes Kalibrierverfahren vorgestellt, bei dem jedes Kamerapixel unabhängig von jedem anderen kalibriert wird.
In the field of smart metering it can be observed that standardized protocol, like Wireless M-Bus or ZigBee, enjoy a rapidly increasing popularity. For the protocol implementations, however, up to now, mostly legacy engineering processes and technologies are used, and modern approaches such as model driven design processes or open software platform are disregarded. Therefore, within the WiMBex project, it shall be demonstrated that it is possible to develop a commercial class Wireless M-Bus implementation following state-of-the art design process and using TinyOS as an open source platform. This contribution describes the overall approach of the project, as well as the state and the first experiences of the current work in progress.
MITK-OpenIGTLink for combining open-source toolkits in real-time computer-assisted interventions
(2016)
PURPOSE:
Due to rapid developments in the research areas of medical imaging, medical image processing and robotics, computer-assisted interventions (CAI) are becoming an integral part of modern patient care. From a software engineering point of view, these systems are highly complex and research can benefit greatly from reusing software components. This is supported by a number of open-source toolkits for medical imaging and CAI such as the medical imaging interaction toolkit (MITK), the public software library for ultrasound imaging research (PLUS) and 3D Slicer. An independent inter-toolkit communication such as the open image-guided therapy link (OpenIGTLink) can be used to combine the advantages of these toolkits and enable an easier realization of a clinical CAI workflow.
METHODS:
MITK-OpenIGTLink is presented as a network interface within MITK that allows easy to use, asynchronous two-way messaging between MITK and clinical devices or other toolkits. Performance and interoperability tests with MITK-OpenIGTLink were carried out considering the whole CAI workflow from data acquisition over processing to visualization.
RESULTS:
We present how MITK-OpenIGTLink can be applied in different usage scenarios. In performance tests, tracking data were transmitted with a frame rate of up to 1000 Hz and a latency of 2.81 ms. Transmission of images with typical ultrasound (US) and greyscale high-definition (HD) resolutions of [Formula: see text] and [Formula: see text] is possible at up to 512 and 128 Hz, respectively.
CONCLUSION:
With the integration of OpenIGTLink into MITK, this protocol is now supported by all established open-source toolkits in the field. This eases interoperability between MITK and toolkits such as PLUS or 3D Slicer and facilitates cross-toolkit research collaborations. MITK and its submodule MITK-OpenIGTLink are provided open source under a BSD-style licence ( http://mitk.org )
Machine-to-machine communication is continuously extending to new application fields. Especially smart metering has the potential to become the first really large-scale M2M application. Although in the future distributed meter devices will be mainly connected via dedicated primary communication protocols, like ZigBee, Wireless
M-Bus or alike, a major percentage of all meters will be connected via point to point communication using GPRS or UMTS platforms. Thus, such meter devices have to be extremely cost and energy efficient, especially if the devices are battery based and powered several years by a single battery. This paper presents the development of an automated measurement unit for power and time, thus energy characteristics can be recorded. The measurement unit includes a hardware platform for the device
under test (DUT) and a database based software environment for a smooth execution and analysis of the measurements.
Flexible Three-dimensional Camera-based Reconstruction and Calibration of Tracked Instruments
(2016)
Navigated instruments commonly include applied parts, e.g. burrs or saw blades, that need to be calibrated with respect to the attached or integrated tracker. Since this calibration has to be very precise, it is often performed by the manufacturer. However, due to the great variety of instruments and the option to exchange the applied parts (e.g. burrs) there is a definite demand for flexible and generic calibration techniques. Furthermore, if we look into the medical field, there is also a need for calibrating sterile instruments. We propose a new and flexible camera-based calibration technique that addresses these demands by working contactlessly, precisely, and generically for a large variety of tracked instruments. This is realized using one or more tracked cameras which are calibrated with respect to an attached or integrated tracker. The tracked instrument is rotated in front of the camera(s) and its 3D geometry and surface are reconstructed from the 2D images in the coordinate system of the attached or integrated tracker. The 3D geometry of the navigated instrument was reconstructed with an accuracy of under 0.2 mm. The radius of a sphere-shaped instrument was reconstructed with an RMS deviation of 0.015mm.
Nowadays, robotic systems are an integral part of many orthopedic interventions. Stationary robots improve the accuracy but also require adapted surgical workflows. Handheld robotic devices (HHRDs), however, are easily integrated into existing workflows and represent a more economical solution. Their limited range of motion is compensated by the dexterity of the surgeon. This work presents control algorithms for HHRDs with multiple degrees of freedom (DOF). These algorithms protect pre- or intraoperatively defined regions from being penetrated by the end effector (e.g., a burr) by controlling the joints as well as the device’s power. Accuracy tests on a stationary prototype with three DOF show that the presented control algorithms produce results similar to those of stationary robots and much better results than conventional techniques. This work presents novel and innovative algorithms, which work robustly, accurately, and open up new opportunities for orthopedic interventions.