Temporal Sentence Grounding in Video (TSGV) is troubled by dataset bias issue, which is caused by the uneven temporal distribution of the target moments for samples with similar semantic components in input videos or query texts. Existing methods resort to utilizing prior knowledge about bias to artificially break this uneven distribution, which only removes a limited amount of significant language biases. In this work, we propose the bias-conflict sample synthesis and adversarial removal debias strategy (BSSARD), which dynamically generates bias-conflict samples by explicitly leveraging potentially spurious correlations between single-modality features and the temporal position of the target moments. Through adversarial training, its bias generators continuously introduce biases and generate bias-conflict samples to deceive its grounding model. Meanwhile, the grounding model continuously eliminates the introduced biases, which requires it to model multi-modality alignment information. BSSARD will cover most kinds of coupling relationships and disrupt language and visual biases simultaneously. Extensive experiments on Charades-CD and ActivityNet-CD demonstrate the promising debiasing capability of BSSARD. Source codes are available at https://github.com/qzhb/BSSARD.

Video activity anticipation aims to predict what will happen in the future, embracing a broad application prospect ranging from robot vision and autonomous driving. Despite the recent progress, the data uncertainty issue, reflected as the content evolution process and dynamic correlation in event labels, has been somehow ignored. This reduces the model generalization ability and deep understanding on video content, leading to serious error accumulation and degraded performance. In this paper, we address the uncertainty learning problem and propose an uncertainty-boosted robust video activity anticipation framework, which generates uncertainty values to indicate the credibility of the anticipation results. The uncertainty value is used to derive a temperature parameter in the softmax function to modulate the predicted target activity distribution. To guarantee the distribution adjustment, we construct a reasonable target activity label representation by incorporating the activity evolution from the temporal class correlation and the semantic relationship. Moreover, we quantify the uncertainty into relative values by comparing the uncertainty among sample pairs and their temporal-lengths. This relative strategy provides a more accessible way in uncertainty modeling than quantifying the absolute uncertainty values on the whole dataset. Experiments on multiple backbones and benchmarks show our framework achieves promising performance and better robustness/interpretability.

Temporal sentence grounding in video has witnessed significant advancements, but suffers from substantial dataset bias, which undermines its generalization ability. Existing debias approaches primarily concentrate on well-known distribution and linguistic biases, while overlooking the relationship among different biases, limiting their debias capability. In this work, we delve into the existence of visual bias and combinatorial bias in the widely used datasets, and introduce a collaborative debias structure that can be seamlessly integrated into present methods. It encompasses four low-capacity models, a re-label module, and a main model. Each biased model deliberately leverages bias as shortcut information to accurately perform grounding, achieved by customizing the appropriate model structure and input data format to align with the bias characteristics. During the training phase, the gradient descent direction for optimizing the main model should align with the negative gradient descent direction of the biased model that is optimized by utilizing ground truth labels. Subsequently, the re-label module introduces a gradient aggregation function, consolidating the gradient descent direction from these biased models and constructing new labels to compel the main model to effectively capture multi-modality alignment features instead of relying on shortcut contents for grounding. Finally, we design two debias structures, P-Debias and C-Debias, to exploit the independence and inclusion relationships between different types of biases. Extensive experiments on multiple span-based models over Charades-CD and ActivityNet-CD demonstrate the exceptional debias capability of our strategy.

Integrating LiDAR and camera data is crucial for precise 3D object detection. Existing methods resort to augmenting virtual points from 2D image space in a random manner to complete the appearance of 3D objects with sparse points. However, these augmented virtual points have unreasonable 3D positions and representations, which brings serious negative effects on accurate detection. To this end, we introduce a general 3D object detection framework called Virtual Point Augmenting (VPA) to enrich the 3D point cloud by controllably generating virtual points with accurate depth and position information as well as domain-gap-eliminated multi-modal representations from image and point cloud spaces. VPA contains two core designs, namely Hybrid Sampling Method (HSM) and Fine-Grained Cross-modal Fusion (FGCF). HSM uses the constructed seed point distribution map based on the edge score and mask score map to sample high-quality seed points, and employs a feature similarity function to sample with k neighbors’ depth to obtain more accurate depth for the seed points, thereby enhancing the quality of the virtual points’ 3D positions. FGCF fuses the multi-modal features, i.e., the semantic feature, the geometric feature from the image space, and the 3D position feature in an adaptive manner using self-attention mechanism, thereby further improving the representation of the virtual points. We apply VPA to the LiDAR-based method CenterPoint and fusion-based method Cross-modal transformer. Experimental results on the nuScenes, KITTI, and Waymo benchmarks validate the efficiency of our VPA, which achieves promising performance with 72.9% mAP and 74.8% NDS without using test-time augmentation and model ensemble techniques on the nuScenes test set. Code is available at https://github.com/jianpingZhonggit/vpa.git.