Self-Aligning Depth-Regularized Radiance Fields for Asynchronous RGB-D Sequences

It has been shown that learning radiance fields with depth rendering and depth supervision can effectively promote the quality and convergence of view synthesis. However, this paradigm requires input RGB-D sequences to be synchronized. In the UAV city modeling scenario, there exists asynchrony between RGB images and depth images due to the different frequencies of the solid-state LiDAR and RGB sensors. To synthesize high-quality views in such a scenario, we propose a novel time-pose function, which is an implicit network that maps timestamps to SE(3) elements. To train this function, we also design a joint optimization scheme to jointly learn the large-scale depth-regularized radiance fields and the time-pose function. Furthermore, we propose a large synthetic dataset with diverse controlled mismatches and ground truth to evaluate this new problem setting systematically. The proposed approach has been evaluated on both datasets and in a real drone. To evaluate the impact of view density, each algorithm was test on three different trajectories with different view densities. Compared to state-of-the-art baseline methods, the proposed approach reduces reconstruction error by 35.26% in city modeling scenarios. Our code is available at github.com/saythe17/AsyncNeRF.