The current full-waveform data at a single wavelength can mainly retrieve the geometric attributes of targets along the light path by detecting waveform components, resulting in the lack of spectral or color attribute information. This kind of device relies on a digital camera for acquiring the color information, however, which is inevitably limited by the lighting conditions and geometric registration errors. With the development of multispectral light detection and ranging (LiDAR) or even hyperspectral LiDAR that often utilize a supercontinuum laser source covering the whole visible light band, including red, green and blue bands, the simultaneous acquisition of color and spatial information becomes possible and makes passive imaging data no longer necessary. In this study, we propose a color restoration method for a full-waveform multispectral LiDAR (FWMSL) system. Additionally, we develop a multispectral lognormal function to fit the tailing echoes measured by FWMSL further accurately. Experimental data from our FWMSL system are used to evaluate the performance of the proposed method. The relative standard deviation, correlation coefficient (R 2 ) and color difference (∆E) metrics suggest that the color restoration for the full-waveform multispectral data is feasible. (Figure 1b), the RGB bands, namely, 434.5-474.5, 517-537 and 612-644 nm, in the visible spectral portion were selected for the receiving channels of color information. In addition, the photo multiplier tube (PMT) selected as the detector should be more suitable for detecting laser echoes in visible bands than the avalanche photodiode especially in the relatively low-energy B band since PMT has higher quantum efficiency and gain. Moreover, both the transmitted pulse and receiving echo at RGB bands are full-waveform recorded so that the receiving echoes can be calibrated with the transmitted pulses to eliminate errors caused by laser output energy instability. The waveforms of the three receiving channels were digitized in a 12-bit analog to digital converter (SP Devices, ADQ412), with a 1.8 GHz sampling rate. The length of each active signal is set to 20 samples based on the laser pulse width of 2 ns and sampling rate, thus greatly reducing the amount of data. Remote Sens. 2019, 11, x FOR PEER REVIEW 3 of 19 photo multiplier tube (PMT) selected as the detector should be more suitable for detecting laser 96 echoes in visible bands than the avalanche photodiode especially in the relatively low-energy B band 97 since PMT has higher quantum efficiency and gain. Moreover, both the transmitted pulse and 98 receiving echo at RGB bands are full-waveform recorded so that the receiving echoes can be 99 calibrated with the transmitted pulses to eliminate errors caused by laser output energy instability.
100The waveforms of the three receiving channels were digitized in a 12-bit analog to digital converter 101 (SP Devices, ADQ412), with a 1.8 GHz sampling rate. The length of each active signal is set to 20 102 samples based on the laser pulse width of 2 ns a...