We study weakly-supervised video object grounding: given a video segment and a corresponding descriptive sentence, the goal is to localize objects that are mentioned in the sentence in the video. During training, no object bounding boxes are available, but the set of possible objects to be grounded is known beforehand. Existing approaches in the image domain use Multiple Instance Learning (MIL) to ground objects by enforcing matches between visual and semantic features. A naive extension of this approach to the video domain is to treat the entire segment as a bag of spatial object proposals. However, an object existing sparsely across multiple frames might not be detected completely since successfully spotting it from one single frame would trigger a satisfactory match. To this end, we propagate the weak supervisory signal from the segment level to frames that likely contain the target object. For frames that are unlikely to contain the target objects, we use an alternative penalty loss. We also leverage the interactions among objects as a textual guide for the grounding. We evaluate our model on the newly-collected benchmark YouCook2-BoundingBox and show improvements over competitive baselines.

本文研究弱监督视频对象定位问题，并探讨了在图像域中使用的多实例学习方法在视频域中的扩展性。作者提出了一种将弱监督信号从视频层面传递到帧层面的方法，并将对象之间的交互作为定位的文本指导。在新收集的基准测试YouCook2-BoundingBox上，该模型取得了竞争基线方法无法匹敌的表现。

基于损失加权和对象交互的文本弱监督视频对象定位