SPAD LiDAR multi-echo point clouds

In our pixel-scanning Light Detection And Ranging (LiDAR), the field of view (FOV) of a single-photon avalanche diode (SPAD) is larger than the pixel size to avoid miss-detection of small objects. Therefore, the echoes in a single pixel contain the depth information from immediate neighboring pixels, and it can be exploited for enhancing image resolution. When generating high-resolution depth images, existing methods operate on single-echo data and may lead to incorrect displays of depth information. In this letter, by utilizing multi-echo data, we aim to generate accurate depth images and enhance their resolution by four times. In the up-sampling operation, the overlapping characteristics of the FOV are exploited to develop a simple yet effective algorithm to improve depth-image quality. A quantitative metric is also developed to measure the depth accuracy of up-sampled depth images. Experimental results demonstrate that the proposed method improves the accuracy in depth information and enhances the visual effect of delineating objects in complicated scenes.