Exploiting Temporal–Spatial Feature Correlations for Sequential Spacecraft Depth Completion

Abstract

The recently proposed spacecraft three-dimensional (3D) structure recovery method based on optical images and LIDAR has enhanced the working distance of a spacecraft’s 3D perception system. However, the existing methods ignore the richness of temporal features and fail to capture the temporal coherence of consecutive frames. This paper proposes a sequential spacecraft depth completion network (S2DCNet) for generating accurate and temporally consistent depth prediction results, and it can fully exploit temporal–spatial coherence in sequential frames. Specifically, two parallel convolution neural network (CNN) branches were first adopted to extract the features latent in different inputs. The gray image features and the depth features were hierarchically encapsulated into unified feature representations through fusion modules. In the decoding stage, the convolutional long short-term memory (ConvLSTM) networks were embedded with the multi-scale scheme to capture the feature spatial–temporal distribution variation, which could reflect the past state and generate more accurate and temporally consistent depth maps. In addition, a large-scale dataset was constructed, and the experiments revealed the outstanding performance of the proposed S2DCNet, achieving a mean absolute error of 0.192 m within the region of interest.