  3D single object tracking remains a challenging problem due to the sparsity
and incompleteness of the point clouds. Existing algorithms attempt to address
the challenges in two strategies. The first strategy is to learn dense
geometric features based on the captured sparse point cloud. Nevertheless, it
is quite a formidable task since the learned dense geometric features are with
high uncertainty for depicting the shape of the target object. The other
strategy is to aggregate the sparse geometric features of multiple templates to
enrich the shape information, which is a routine solution in 2D tracking.
However, aggregating the coarse shape representations can hardly yield a
precise shape representation. Different from 2D pixels, 3D points of different
frames can be directly fused by coordinate transform, i.e., shape completion.
Considering that, we propose to construct a synthetic target representation
composed of dense and complete point clouds depicting the target shape
precisely by shape completion for robust 3D tracking. Specifically, we design a
voxelized 3D tracking framework with shape completion, in which we propose a
quality-aware shape completion mechanism to alleviate the adverse effect of
noisy historical predictions. It enables us to effectively construct and
leverage the synthetic target representation. Besides, we also develop a
voxelized relation modeling module and box refinement module to improve
tracking performance. Favorable performance against state-of-the-art algorithms
on three benchmarks demonstrates the effectiveness and generalization ability
of our method.
