3D flash lidar has no moving part and can provide high-resolution depth information, so they are attracting attention in development of solid-state lidar system. However, the limited detecting range is key challenge because a single diffused laser source has to cover the whole target area while satisfying the laser-safety requirements. In this paper, we propose a semi-flash lidar system to increase the detecting range while providing high-resolution and wide field-of-view. To increase the peak power of the individual lasers under laser-safety constraint, we design a customized VCSEL array that forming a sparse 2D laser array. We also propose a depth upsampling method to recover the empty pixels in a SPAD detector array which are caused by sparsely distributed laser beam. For robust depth reconstruction, a joint trilateral filter that exploits the ambient light information and structural information of the VCSEL array are presented. Using a hardware prototype, we show the degree of the range enhancement and fidelity of the depth upsampling results under a various environment.
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