One of the major challenges in video object detection is drastic scale changes of objects due to camera motion. In this paper, we propose a two-path Convolutional Long Short-Term Memory (convLSTM) pyramid network designed to extract and convey multi-scale temporal contextual information in order to handle object scale changes efficiently. The proposed two-path convLSTM pyramid consists of a stack of multi-input convLSTM modules. It is updated in top-down and bottom-up pathways so that the temporal contextual information for small-to-large and large-to-small scale changes is exploited. The proposed multi-input convLSTM module uses two input feature maps of different resolutions to store and exchange temporal contextual information of different scales between neighboring convLSTM modules. The outputs of the proposed convLSTM pyramid network constitute a feature pyramid where each feature map contains multi-scale temporal contextual information from earlier frames. The proposed convLSTM pyramid can be combined with various still-image object detectors to improve the performance of video object detection. Experimental results on ImageNet VID dataset show that the proposed method achieves state-of-the-art performance and can handle scale changes efficiently in video object detection.

Transformer-based semantic segmentation methods have achieved excellent performance in recent years. Mask2Former is one of the well-known transformer-based methods which unifies common image segmentation into a universal model. However, it performs relatively poorly in obtaining local features and segmenting small objects due to relying heavily on transformers. To this end, we propose a simple yet effective architecture that introduces auxiliary branches to Mask2Former during training to capture dense local features on the encoder side. The obtained features help improve the performance of learning local information and segmenting small objects. Since the proposed auxiliary convolution layers are required only for training and can be removed during inference, the performance gain can be obtained without additional computation at inference. Experimental results show that our model can achieve state-of-the-art performance (57.6% mIoU) on the ADE20K and (84.8% mIoU) on the Cityscapes datasets.