Anomaly segmentation aims to identify Out-of-Distribution (OoD) anomalous objects within images. Existing pixel-wise methods typi- cally assign anomaly scores individually and employ a global thresh- olding strategy to segment anomalies. Despite their effectiveness, these approaches encounter significant challenges in real-world applications: (1) neglecting spatial correlations among pixels within the same object, resulting in fragmented segmentation; (2) variabil- ity in anomaly score distributions across image regions, causing global thresholds to either generate false positives in background areas or miss segments of anomalous objects. In this work, we intro- duce OoDDINO, a novel multi-level anomaly segmentation frame- work designed to address these limitations through a coarse-to-fine anomaly detection strategy. OoDDINO combines an uncertainty- guided anomaly detection model with a pixel-level segmentation model within a two-stage cascade architecture. Initially, we propose an Orthogonal Uncertainty-Aware Fusion Strategy (OUAFS) that sequentially integrates multiple uncertainty metrics with visual representations, employing orthogonal constraints to strengthen the detection model's capacity for localizing anomalous regions accurately. Subsequently, we develop an Adaptive Dual-Threshold Network (ADT-Net), which dynamically generates region-specific thresholds based on object-level detection outputs and pixel-wise anomaly scores. This approach allows for distinct thresholding strategies within foreground and background areas, achieving fine- grained anomaly segmentation. The proposed framework is compatible with other pixel-wise anomaly detection models, which act as a plug-in to boost the performance. Extensive experiments on two benchmark datasets validate our framework's superiority and compatibility over state-of-the-art methods. Source code is available at: https://github.com/OoDDINO/OoD-DINO.

Anomaly segmentation plays a crucial role in identifying anomalous objects within images, which facilitates the detection of road anomalies for autonomous driving. Although existing methods have shown impressive results in anomaly segmentation using synthetic training data, the domain discrepancies between synthetic training data and real test data are often neglected. To address this issue, Multi-Granularity Cross-Domain Alignment (MGCDA) framework is proposed for anomaly segmentation in complex driving environments. It uniquely combines a new Multi-source Domain Adversarial Training (MDAT) module and a novel Cross-domain Anomaly-aware Contrastive Learning (CACL) method to boost the generality of the model, seamlessly integrating multi-domain data at both scene and sample levels. Multi-source domain adversarial loss and a dynamic label smoothing strategy are integrated into MDAT module to facilitate the acquisition of domain-invariant features at the scene level, through adversarial training across multiple stages. CACL aligns sample-level representations with contrastive loss on cross-domain data, which utilizes an anomaly-aware sampling strategy to efficiently sample hard samples and anchors. The proposed framework has decent properties of parameter-free during the inference stage and is compatible with other anomaly segmentation networks. Experimental conducted on Fishyscapes and RoadAnomaly datasets demonstrate that the proposed framework achieves the state-of-the-art performance.

Real-time semantic segmentation is essential for many practical applications, which utilizes attention-based feature aggregation into lightweight structures to improve accuracy and efficiency. However, existing attention-based methods ignore 1) high-level and low-level feature augmentation guided by spatial information, and 2) low-level feature augmentation guided by semantic context, so that feature gaps between multi-level features and noise of low-level spatial details still exist. To address these problems, a new real-time semantic segmentation network, called MvFSeg, is proposed. In MvFSeg, parallel convolution with multiple depths is designed as a context head to generate and integrate multi-view features with larger receptive fields. Moreover, MvFSeg designs multiple views feature augmentation strategies that exploit spatial and semantic guidance for shallow and deep feature augmentation in an inter-layer and intra-layer manner. These strategies eliminate feature gaps between multi-level features, filter out the noise of spatial details, and provide spatial and semantic guidance for multi-level features. By combining multi-view features and augmented features from the lightweight networks with progressive dense aggregation structures, MvFSeg effectively captures invariance at various scales and generates high-quality segmentation results. Experiments conducted on Cityscapes and CamVid benchmark show that MvFSeg outperforms existing state-of-the-art methods.

Generating high-quality density maps is a crucial step in crowd counting. It is obvious that exploiting the head location of the people can naturally highlight the crowded area and eliminate the interference of background noise. However, existing crowd counting methods are still tricky to reasonably use location in density generation. In this paper, a novel location-guided framework named CrossNet is proposed for crowd counting, which integrates location supervision into density maps through dual-branch joint training. First, a new branching network is proposed to localize the potential positions of pedestrians. With the help of supervision induced from the localization branch, Location Enhancement (LE) module is designed to obtain high-quality density maps by positioning foreground regions. Second, Adaptive Density Awareness Attention (ADAA) module is engaged to enhance localization accuracy, which can efficiently use the density of the counting branch to adaptively capture the error-prone dense areas of the location maps. Finally, Density Awareness Localization (DAL) loss is offered to allocate attention to the crowd density levels, which delivers more focus on regions with high densities and less concentration on areas with low densities. Extensive experiments conducted on four benchmark datasets demonstrate that the proposed method outperforms the state-of-the-art approaches both in crowd counting and crowd localization.

Vehicle counting aims to calculate the number of vehicles in congested traffic scenes. Although object detection and crowd counting have made tremendous progress with the development of deep learning, vehicle counting remains a challenging task, due to scale variations, viewpoint changes, inconsistent location distributions, diverse visual appearances and severe occlusions. In this paper, a well-designed Vehicle Counting Network (VCNet) is novelly proposed to alleviate the problem of scale variation and inconsistent spatial distribution in congested traffic scenes. Specifically, VCNet is composed of two major components: (i) To capture multi-scale vehicles across different types and camera viewpoints, an effective multi-scale density map estimation structure is designed by building an attention-based mask refinement module. The multi-branch structure with hybrid dilated convolution blocks is proposed to assign receptive fields to generate multi-scale density maps. To efficiently aggregate multi-scale density maps, the attention-based mask refinement is well-designed to highlight the vehicle regions, which enables each branch to suppress the scale interference from other branches. (ii) In order to capture the inconsistent spatial distributions, a spatial-awareness block loss (SBL) based on the region-weighted reward strategy is proposed to calculate the loss of different spatial regions including sparse, congested and occluded regions independently by dividing the density map into different regions. Extensive experiments conducted on three benchmark datasets, TRANCOS, VisDrone2019 Vehicle and CVCSet demonstrate that the proposed VCNet outperforms the state-of-the-art approaches in vehicle counting. Moreover, the proposed idea can be applicable for crowd counting, which produces competitive results on ShanghaiTech crowd counting dataset.

Although recent object detectors have shown excellent performance for vehicle detection, they are incompetent for scenarios with a relatively large number of vehicles. In this paper, we explore the dense vehicle detection given the number of vehicles. Existing crowd counting methods cannot directly applied for dense vehicle detection due to insufficient description of density map, and the lack of effective constraint for mining the spatial awareness of dense vehicles. Inspired by these observations, a conceptually simple yet efficient framework, called CODAN, is proposed for dense vehicle detection. The proposed approach is composed of three major components: (i) an efficient strategy for generating multi-scale density maps (MDM) is designed to represent the vehicle counting, which can capture the global semantics and spatial information of dense vehicles, (ii) a multi-branch attention module (MAM) is proposed to bridging the gap between object counting and vehicle detection framework, (iii) with the well-designed density maps as explicit supervision, an effective counting-awareness loss (C-Loss) is employed to guide the attention learning by building the pixel-level constrain. Extensive experiments conducted on four benchmark datasets demonstrate that the proposed method outperforms the state-of-the-art methods. The impressive results indicate that vehicle detection and counting can be mutually supportive, which is an important and meaningful finding.