Fig. 1. Representative HSL architectures. (a) Pre-emission spectral division; (b) post-reception spectral division

Fig. 2. Schematic and photographs of current HSL systems developed by different research institutions. (a) FGI’s portable 8-channel HSL^[21]; (b) CAS’s HSL based on liquid crystal tunable filter (LCTF)^[30]; (c) CAS’s ground-based 32-channel HSL^[31]; (d) Wuhan University’s ground-based 32-channel HSL^[32]; (e) Wuhan University’s airborne 56-channel HSL^[28]; (f) Heriot-Watt University’s multi-spectral lidar based on acousto-optic tunable filter (AOTF)^[33]; (g) Anhui University of Architecture’s 101-channel HSL^[1]

Fig. 3. Multichannel waveforms of HSL and technical route of hyperspectral waveform decomposition. (a) Multichannel waveforms of HSL^[41]; (b) technical route of hyperspectral waveform decomposition

Fig. 4. Three single-wavelength waveform decomposition methods. (a) Direct decomposition^[48]; (b) deconvolution waveform decomposition^[49]; (c) RJMCMC^[33]

Fig. 5. Comparison of prevailing multi/hyperspectral waveform decomposition methods with single-wavelength waveform decomposition methods. (a) Multi waveform decomposition^[50]; (b) hyperspectral waveform decomposition^[28]

Fig. 6. Impact and correction of distance effect^[27]. (a) Distance effect; (b) distance effect correction

Fig. 7. Impact and correction of incident angle effect^[31]. (a) Incident angle effect; (b) incident angle effect correction

Fig. 8. Impact and correction of sub-footprint effect. (a) Sub-footprint effect mechanism^[68]; (b)‒(c) sub-footprint effect correction^[70]

Fig. 9. HSL point cloud imaging technology. (a) Color restoration^[74]; (b) imaging of ancient architecture^[8]; (c) eliminating ‘highlight’ effect^[75]

Fig. 10. Application of HSL point cloud classification. (a) Wood, leaf, and fruit separation^[1]; (b) multi-target classification^[80]; (c) land cover classification^[5]

Fig. 11. Various applications of spectral information from HSL. (a) Detection of plant nitrogen and chlorophyll content distribution^[89-90]; (b) pest and disease detection^[20]; (c) coal and rock identification and classification^[9,91]