Many applications need fast measurement systems that capture their environment in three dimensions. Adequate
measurement sensors are required that provide fast, accurate, and reliable 3-D data. Automotive applications long for
real time and reliable data, not only for driving assistance systems but for safety, also. Until now, most solutions, like
multi image photogrammetry, radar sensors or laser scanners, lack in one of these aspects at least. With the upcoming
range imaging cameras, new sensors with a performance never seen before are to be taken into consideration. Range
imaging has already been proved as an emerging technology for automotive applications. These cameras provide a
distance measurement system in each pixel and therefore produce 3-D data with up to video frame rates with a single
sensor. But because of their new measurement concept classical calibration approaches cannot be used. This paper will
present results of research about the calibration of the SwissRangerTM, a range imaging camera introduced by CSEM
Switzerland. Special emphasis is given to the determination of the influence of the diverse parameters on the distance
measurement accuracy. These parameters are the temperature, the reflectivity and the distance itself, for example. The
influences are represented in functional dependencies in order to reach high accuracy of the system. Temperature
compensation by means of a specialized setup is addressed. A successful implementation of a temperature drift
compensation by means of a differential setup is presented.
Range Imaging (RIM) is a new suitable choice for measurement and modeling in many different applications. RIM is a fusion of two
different technologies. According to the terminology, it integrates distance measurement as well as imaging aspects. The distance
measurement principle is dominated by the time-of-flight principle while the imaging array (e.g. CMOS sensor) enables each pixel to
store also the distance towards the corresponding object point. Due to the technology's relatively new appearance on the market, with
a few different realizations, the knowledge of its capabilities is very low.
In this paper we present our investigations on the range imaging camera SwissRangerTM (realized by the Swiss Center for Electronics
and Microtechnology, CSEM). Different calibration procedures are performed, including a photogrammetric camera calibration and
a distance system calibration with respect to the reflectivity and the distance itself. Furthermore we report about measurement
applications in the field of surveillance and biometrics. In particular, range imaging data of moving people are analyzed, to identify
humans, detect their movements and recover 3D trajectories.
Many security & defense systems need to capture their environment in one, two or even three dimensions. Therefore adequate measurement sensors are required that provide fast, accurate and reliable 3D data. With the upcoming range imaging cameras, like the SwissRangerTM introduced by CSEM Switzerland, new cheap sensors with such ability and high performance are available on the market. Because of the measurement concept these sensors long for a special calibration approach. Due to the implementation of several thousand distance measurement systems as pixels, a standard photogrammetric camera calibration is not sufficient. This paper will present results of investigations on the accuracy of the range imaging camera SwissRanger. A systematic calibration method is presented which takes into consideration the different influencing parameters, like reflectivity, integration time, temperature and distance itself. The analyzed parameters with respect to their impact on the distance measuring pixels and their output data were determined. The investigations were mainly done on the high precision calibration track line in the calibration laboratory at ETH Zurich, which provides a relative accuracy of several microns. In this paper it will be shown, under which circumstances the goal accuracy of the sub centimeter level can be reached. The results of this work can be very helpful for users of range imaging systems to increase their accuracy and thus the reliability of their systems. As an example, the usefulness of a range imaging camera in security systems for room surveillance is presented.
In recent years, pervasive computing has become an important topic in automobile industry. Besides well-known driving assistant systems such as ABS, ASR and ESP several small tools that support driving activities were developed. The most important reason for integrating new technologies is to increase the safety of passengers as well as road users. The Centre Suisse d'Electronique et de Microtechnique SA (CSEM) Zurich presented the CMOS/CCD real-time range-imaging technology, a measurement principle with a wide field of applications in automobiles. The measuring system is based on the time-of-flight measurement principle using actively modulated radiation. Thereby, the radiation is emitted by the camera's illumination system, reflected by objects in the field of view and finally imaged on the CMOS/CCD sensor by the optics. From the acquired radiation, the phase delay and hence the target distance is derived within each individual pixel. From these distance measurements, three-dimensional coordinates can then be calculated. The imaging sensor acquires its environment data in a high-frequency mode and is therefore appropriate for real-time applications. The basis for decisions which contribute to the increased safety is thus available. In this contribution, first the operational principle of the sensor technology is outlined. Further, some implementations of the technology are presented. At the laboratories of the Institute of Geodesy and Photogrammetry (IGP) at ETH Zurich an implementation of the above mentioned measurement principle, the SwissRanger, was investigated in detail. Special attention was focused on the characteristics of this sensor and its calibration. Finally, sample applications within the automobile are introduced.
3D-coordinate producing systems have become very successful in the recent years. Aerial and terrestrial laser scanners are now ‘state-of-the-art’ to get information of the third and forth dimension and replace photogrammetric camera systems. Laser scanners typically have a very high point density, but because of their sequential mode of operation their shortcomings are both their speed of acquisition and their size.
The new range-imaging camera SwissRanger, developed by Centre Suisse d'Electronique et de Microtechnique SA (CSEM), is the first step to a follow-up generation of 3D-measurement systems and gets over the shortcomings and disadvantages of current photogrammetric systems and laser scanners. Because of its high-resolution with more than twenty thousand pixel, the created 3D-dataset even allows deducing geometrical information of the environment. The accuracy of the acquired distance is approximately 1 cm. Temporal resolution depends on various parameters like integration time, soft- and hardware. But five Hertz image sequences can be easily reached. Therefore, (near) real-time measurements are possible.
Several influencing parameters have been investigated in the calibration Lab of the Institute of Geodesy and Photogrammetry at the Swiss Federal Institute of Technology Zurich (Switzerland).
Besides first experiences and analysis of the data, acquired by the SwissRanger, a suitable approach for the calibration of such a system is to be considered and validated. First, a two-component calibration splits the sensor into a camera and a range measuring module. Both are calibrated separately with common known methods. The results of this calibration approach are compared to a newly developed single-step calibration. Hereby, the sensor is regarded as one single (black box) system. No assumption about the internal model is necessary. The results of the calibration are used for the improvement of the measurements.
Further, new applications for such a 3D-positioning system are presented. Besides the usefulness of the SwissRanger in car parking assistant systems, the applicability for an indoor positioning system is evaluated. The required accuracy and precision are focused.
Conference Committee Involvement (1)
Photonic Applications for Aerospace, Transportation, and Harsh Environment III
23 April 2012 | Baltimore, Maryland, United States