The contactless estimation of vital signs based on conventional color cameras and ambient light can be affected by motions of patients and changes in ambient light. In this work, a multimodal 3D imaging system with an irritation-free controlled illumination was developed in order to mitigate these both problems. In the developed system the real-time high-precision 3D imaging is combined with VIS-NIR multispectral imaging and thermal imaging. Based on 3D data and color images, an approach was proposed for the efficient compensation of head motions, and novel approaches based on 3D regions of interest were developed for the estimation of heart rate, oxygen saturation, respiration rate, and body temperature from NIR multispectral video data and thermal video data. A proof-of-concept for the developed imaging system and algorithms can be delivered with first experimental results.
KEYWORDS: Cameras, 3D metrology, Temperature metrology, Long wavelength infrared, Sensors, Calibration, 3D image processing, Infrared cameras, Thermography, 3D acquisition
For the measurement of three-dimensional (3D) shapes, active optical measurement systems based on pattern projection are widely used. These sensors work without contact and are non-destructive. Between one camera and the projector or between two cameras, the 3D reconstruction is performed by detection and triangulation of corresponding image points. Recently, we developed a 3D stereo sensor working in the visible range of light (VIS). It consists of two highspeed cameras and a GOBO projection-based high-speed pattern projector. Our system allows us to successfully reconstruct 3D point clouds of fast processes such as athletes in motion or even crash tests. Simultaneously measuring the surface temperature would be of great benefit as fast processes usually exhibit local temperature changes. In order to include thermal data into the evaluation, we have extended our existing high-speed 3D sensor by including an additional high-speed long-wave infrared (LWIR) camera. The thermal camera detects radiation in the spectral range between 7.5 and 12 μm. We map the measured temperatures as texture onto the reconstructed 3D points. In this contribution, we present the design of this novel 5D (three spatial coordinates, temperature, and time) sensor. The simultaneous calibration process of the VIS cameras and the LWIR camera in a common coordinate system is described. First promising measurements of an inflating airbag, a basketball player, and the crushing of a metal tube performed at a frame rate of 1 kHz are shown. Keywords: high-speed visible (VIS) and infrared (IR) cameras, 3D shape measurement, multimodal sensor, GOBO projection, aperiodic sinusoidal patterns, temperature mapping
KEYWORDS: Cameras, 3D metrology, Long wavelength infrared, Temperature metrology, Thermography, Calibration, 3D image processing, Sensors, High speed cameras, Imaging systems
Pattern projection-based three-dimensional (3D) measurement systems are widely used for contactless, nondestructive, and full-field optical 3D shape measurements. 3D reconstruction is performed between one camera and the projector or between two cameras by detection and triangulation of corresponding image points. In order to record fast processes, such as people in motion or even explosions and crashes, we have recently developed a 3D stereo sensor consisting of two high-speed cameras and a GOBO projection-based high-speed pattern projector. The system, which works in the visible wavelength range (VIS), enables us to successfully reconstruct 3D point clouds of athletes in action, crash tests, or airbag inflations. However, as such processes usually exhibit local temperature changes, simultaneously measuring the surface temperature would be of great benefit. Therefore, we have extended our existing high-speed 3D sensor by including an additional high-speed longwave infrared (LWIR) camera, which detects radiation in the spectral range between 7.5 and 12 μm. The setup allows us to map the recorded temperature data onto the reconstructed 3D points. We present the design of this novel 5D (three spatial coordinates, temperature, and time) sensor and the process of simultaneously calibrating the VIS cameras and the LWIR camera in a common coordinate system. Moreover, we show first promising measurements of an inflating airbag and a basketball player conducted at a frame rate of 1 kHz.
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