  The performance of video saliency estimation techniques has achieved
significant advances along with the rapid development of Convolutional Neural
Networks (CNNs). However, devices like cameras and drones may have limited
computational capability and storage space so that the direct deployment of
complex deep saliency models becomes infeasible. To address this problem, this
paper proposes a dynamic saliency estimation approach for aerial videos via
spatiotemporal knowledge distillation. In this approach, five components are
involved, including two teachers, two students and the desired spatiotemporal
model. The knowledge of spatial and temporal saliency is first separately
transferred from the two complex and redundant teachers to their simple and
compact students, and the input scenes are also degraded from high-resolution
to low-resolution to remove the probable data redundancy so as to greatly speed
up the feature extraction process. After that, the desired spatiotemporal model
is further trained by distilling and encoding the spatial and temporal saliency
knowledge of two students into a unified network. In this manner, the
inter-model redundancy can be further removed for the effective estimation of
dynamic saliency on aerial videos. Experimental results show that the proposed
approach outperforms ten state-of-the-art models in estimating visual saliency
on aerial videos, while its speed reaches up to 28,738 FPS on the GPU platform.
