  We present iSDF, a continual learning system for real-time signed distance
field (SDF) reconstruction. Given a stream of posed depth images from a moving
camera, it trains a randomly initialised neural network to map input 3D
coordinate to approximate signed distance. The model is self-supervised by
minimising a loss that bounds the predicted signed distance using the distance
to the closest sampled point in a batch of query points that are actively
sampled. In contrast to prior work based on voxel grids, our neural method is
able to provide adaptive levels of detail with plausible filling in of
partially observed regions and denoising of observations, all while having a
more compact representation. In evaluations against alternative methods on real
and synthetic datasets of indoor environments, we find that iSDF produces more
accurate reconstructions, and better approximations of collision costs and
gradients useful for downstream planners in domains from navigation to
manipulation. Code and video results can be found at our project page:
https://joeaortiz.github.io/iSDF/ .
