Paper ID | ARS-8.4 | ||
Paper Title | PUNet: Temporal Action Proposal Generation with Positive Unlabeled Learning using Key Frame Annotations | ||
Authors | Noor ul Sehr Zia, Osman Semih Kayhan, Jan C. van Gemert, Delft University of Technology, Netherlands | ||
Session | ARS-8: Image and Video Mid-Level Analysis | ||
Location | Area I | ||
Session Time: | Monday, 20 September, 13:30 - 15:00 | ||
Presentation Time: | Monday, 20 September, 13:30 - 15:00 | ||
Presentation | Poster | ||
Topic | Image and Video Analysis, Synthesis, and Retrieval: Image & Video Mid-Level Analysis | ||
IEEE Xplore Open Preview | Click here to view in IEEE Xplore | ||
Abstract | Popular approaches to classifying action segments in long, realistic, untrimmed videos start with high quality action proposals. Current action proposal methods based on deep learning are trained on labeled video segments. Obtaining annotated segments for untrimmed videos is time consuming, expensive and error-prone as annotated temporal action boundaries are imprecise, subjective and inconsistent. By embracing this uncertainty we explore to significantly speed up temporal annotations by using just a single key frame label for each action instance instead of the inherently imprecise start and end frames. To tackle the class imbalance by using only a single frame, we evaluate an extremely simple Positive-Unlabeled algorithm (PU-learning). We demonstrate on THUMOS'14 and ActivityNet that using a single key frame label give good results while being significantly faster to annotate. In addition, we show that our simple method, PUNet, is data-efficient which further reduces the need for expensive annotations. |