Get started quickly with 3D time-of-flight applications
Design complexity rises quickly as developers work to enhance the signal to noise ratio (SNR) and eliminate artifacts in ToF systems. Further compounding complexity, more advanced detection solutions will employ multiple transmitters and receivers to track multiple objects or support more sophisticated motion tracking algorithms. For example, mmWave systems will often employ multiple receivers to track the heading and velocity of multiple independent objects. (See, "Use Millimeter Wave Radar Kits for Fast Development of Precision Object Detection Designs ".) 3D optical ToF systems 3D optical ToF systems extend the idea of using more receivers by using imaging sensors typically based on an array of charge-coupled devices (CCDs). When a set of lenses focuses some region of interest onto the CCD array, each charge storage device in the CCD array is charged by the return illumination reflected from a corresponding point in that region of interest. Synchronized with pulsed or continuous wave illumination, reflected light reaching the CCD array is essentially captured in a sequence of windows or phases, respectively. This data is further processed to create a 3D depth map comprising voxels (VOlume
piXELs) whose value represents the distance to the corresponding point in the region of interest. Like frames in a video, individual depth maps can be captured in sequence to provide measurements with temporal resolution limited only by the frame rate of the image capture system and with spatial resolution limited only by the CCD array and optical system. With the availability of larger 320 x 240 CCD imagers, higher resolution 3D optical ToF systems find applications in broadly diverse segments including industrial automation, unmanned aerial vehicles (UAVs), and even gesture interfaces (Figure 2).
Unlike most camera-based methods, 3D ToF systems can provide accurate results despite shading or changing lighting conditions. These systems provide their own illumination, typically using lasers or high-power infrared LEDs such as Lumileds' Luxeon IR LEDs able to operate at the megahertz (MHz) switching rates used in these systems. Unlike methods such as stereoscopic cameras, 3D ToF systems provide a compact solution for generating detailed distance information.
Figure 2: With their high frame rate and spatial resolution, 3D optical ToF can provide gesture interface systems with detailed data such as a person's hand being raised toward the ToF camera as shown here. (Image source: ESPROS Photonics)
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