124 research outputs found
EMScore: Evaluating Video Captioning via Coarse-Grained and Fine-Grained Embedding Matching
Current metrics for video captioning are mostly based on the text-level
comparison between reference and candidate captions. However, they have some
insuperable drawbacks, e.g., they cannot handle videos without references, and
they may result in biased evaluation due to the one-to-many nature of
video-to-text and the neglect of visual relevance. From the human evaluator's
viewpoint, a high-quality caption should be consistent with the provided video,
but not necessarily be similar to the reference in literal or semantics.
Inspired by human evaluation, we propose EMScore (Embedding Matching-based
score), a novel reference-free metric for video captioning, which directly
measures similarity between video and candidate captions. Benefit from the
recent development of large-scale pre-training models, we exploit a well
pre-trained vision-language model to extract visual and linguistic embeddings
for computing EMScore. Specifically, EMScore combines matching scores of both
coarse-grained (video and caption) and fine-grained (frames and words) levels,
which takes the overall understanding and detailed characteristics of the video
into account. Furthermore, considering the potential information gain, EMScore
can be flexibly extended to the conditions where human-labeled references are
available. Last but not least, we collect VATEX-EVAL and ActivityNet-FOIl
datasets to systematically evaluate the existing metrics. VATEX-EVAL
experiments demonstrate that EMScore has higher human correlation and lower
reference dependency. ActivityNet-FOIL experiment verifies that EMScore can
effectively identify "hallucinating" captions. The datasets will be released to
facilitate the development of video captioning metrics. The code is available
at: https://github.com/ShiYaya/emscore.Comment: cvpr202
Observation of giant nonreciprocal charge transport from quantum Hall edge states of single surface in topological insulator
Symmetry breaking in quantum materials is of great importance and leads to
novel nonreciprocal charge transport. The topological insulator system provides
a unique platform to study nonreciprocal charge transport due to the exotic
surface state. But it is typically small in magnitude because the contributions
from the top and bottom surface of topological insulator are usually opposite.
Here, we report the observation of giant nonreciprocal charge transport
mediated by the quantum Hall state in intrinsic topological insulator
Sn-Bi1.1Sb0.9Te2S devices, which is attributed to the coexistence of quantum
Hall states and Dirac surface states. A giant nonreciprocal coefficient of up
to 2.26*10^5 A^-1 is found, because only a single surface of topological
insulator contributes to the nonreciprocal charge transport. Our work not only
reveals the intrinsic properties of nonreciprocal charge transport in
topological insulators, but also paves the way for future electronic devices
- …