Mobile laser scanning (MLS) is the latest approach towards fast and cost-e‰cient acquisition of 3-dimensional spatial data. Accurately evaluating the boresight alignment in MLS systems is an obvious necessity. However, recent systems available on the market may lack of suitable and e‰cient practical workflows on how to perform this calibration. This paper discusses an innovative method for accurately determining the boresight alignment of MLS systems by employing 3D laser scanners. Scanning objects using a 3D laser scanner operating in a 2D line-scan mode from various di¤erent runs and scan directions provides valuable scan data for determining the angular alignment between inertial measurement unit and laser scanner. Field data is presented demonstrating the final accuracy of the calibration and the high quality of the point cloud acquired during an MLS campaign.

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Within this work an integrated range finding single pixel sensor manufactured in a standard 90nm CMOS technology is presented. The sensor works on the time-of-flight principle obtaining the distance information out of the correlated sent and received signals. The implementation of a range-finding sensor in 90nm technology is using the most advanced process for a distance sensor up to now based on the bridge circuit. Background light suppression is inherently provided in the pixel sensor. The pixel facilitates a high fill factor accounting to 90% at an area of 50 × 64 µm² and has a power consumption of 2 µW. Measurement results show a standard deviation of 2 cm at 1.2 m covering the range from 0.2 to 3.2 m at 120 klx background illumination.

Real-time 3D imaging has reached a state of development where several fields of application are possible, such as factory automation, consumer electronics, security, and robotics. The first commercial products have already been launched, or will be available soon. Accuracies in the centimeter range or even below, low cost, and robustness to disturbances in realistic indoor and outdoor environments are the key performance demands for these sensors, which are mostly based on the time-of-flight (TOF) principle either in pulsed or continuouswave (CW) mode.Results with single-photon avalanche diodes (SPADs) and an array size of 128×128 pixels [1] permit a standard deviation of 1.4mm between two range maps after a measurement time of 1s with 0.25W solid-state laser pulses. Ambient light and/or temperature increase the dark-count rate of SPADs significantly, which dramatically reduces accuracy. The CW phase-correlation method is used in [2] and in PMD sensors [3], both based on opto-electronic mixer devices and realized in CCD-CMOS and CMOS technology, respectively. IR bandpass filters are used to attenuate undesired background light in order to guarantee functionality up to 50% of bright sunlight [2]. A filter attenuation factor of ~10 and burst-mode operation, which enhances the optical signal-to-noise ratio (SNR) by an additional factor of 5, make distance measurements feasible at conditions up to 726W/m² sunlight, which corresponds to about 90klx [3]. Similar techniques are applied to the 3D sensors in [4]. A triangulation-based VGA range imager [5] achieves up to 65fps with an error of 0.87mm at a distance of 1.2m utilizing a 0.3W laser scanning system, neglecting any ambient light considerations.We present a TOF-pixel circuit managing up to 120klx of ambient light without using any optical filter or burst-mode operation for optical SNR enhancement. The challenging task is to suppress the huge DC photocurrent I BGL due to ambient light that is decades larger in the worst case than the contribution of modulated light I MOD . Subtraction within one integration period might be the most obvious approach to solve this problem, by introducing the bridge-correlator concept [6]. Unfortunately, this topology suffers from insensitivity due to the parasitic capacitance of the photodiode. Figure 20.7.1 shows a pixel circuit based on a correlation principle. The received current I MOD due to modulated light, which is transmitted by an external light source and backscattered at a range object, is correlated with the on-chip clock at switches S 1 and S 2 . Capacitors C 1 and C 2 (C 1 = C 2 ) accumulate the received photocurrent I PH = I MOD + I BGL generated by photodiode D PIN . The modulation clock of the external light source is locked to the pixel modulation clock (at S 1 and S 2 ), and shifted by 2π/16 with every phase integration step, as outlined in the timing diagram of Fig. 20.7.1 for I MOD . In total, 16 phase steps are used to obtain the discrete triangle correlation function, out of which the distance information d is...