Low-cost, vision-centric 3D perception systems for autonomous driving have made significant progress in recent years, narrowing the gap to expensive LiDAR-based methods. The primary challenge in becoming a fully reliable alternative lies in robust depth prediction capabilities, as camera-based systems struggle with long detection ranges and adverse lighting and weather conditions. In this work, we introduce HyDRa, a novel camera-radar fusion architecture for diverse 3D perception tasks. Building upon the principles of dense Bird's-EyeView (BEV)-based architectures, HyDRa introduces a hybrid fusion approach to combine the strengths of complementary camera and radar features in two distinct representation spaces. Our Height Association Transformer module leverages radar features already in the perspective view to produce more robust and accurate depth predictions. In the BEV, we refine the initial sparse representation by a Radar-weighted Depth Consistency. HyDRa achieves a new state-of-the-art for cameraradar fusion of 64.2 NDS (+1.8) and 58.4 AMOTA (+1.5) on the public nuScenes dataset. Moreover, our new semantically rich and spatially accurate BEV features can be directly converted into a powerful occupancy representation, beating all previous camera-based methods on the Occ3D benchmark by an impressive 3.7 mIoU. Code and models are available at https://github.com/phi-wol/hydra.

In the area of foreground and background segmentation the dynamics of a scene often influence the model of the background. There exist different methods trying to overcome the difficulty in estimating and handling these dynamics. In this paper, we propose an adaption of proportional-integral-derivative (PID) controllers to this regulation problem. In our approach, PID controllers regulate the decision threshold of the background dynamics and the update rate of the background model. The regulators are integrated in the Pixel-based Adaptive Segmenter (PBAS), which is publicly available and offers good results in the Change Detection challenge. We show that the performance of the PBAS can be further improved through an empirical tuning of the single PID constants.

We generalize the network flow formulation for multiobject tracking to multi-camera setups. In the past, reconstruction of multi-camera data was done as a separate extension. In this work, we present a combined maximum a posteriori (MAP) formulation, which jointly models multicamera reconstruction as well as global temporal data association. A flow graph is constructed, which tracks objects in 3D world space. The multi-camera reconstruction can be efficiently incorporated as additional constraints on the flow graph without making the graph unnecessarily large. The final graph is efficiently solved using binary linear programming. On the PETS 2009 dataset we achieve results that significantly exceed the current state of the art.

With this work, we address the problem of acoustic gait-based person identification, which is the task of identifying humans by the sounds they make while walking. We examine several acoustic features from speech processing tasks for their suitability for acoustic gait recognition. Using a wrapper-based feature selection technique, we reduce the feature set while at the same time increasing the identification accuracy by 10% (relative). For classification, Support Vector Machines (SVMs) are employed. Experiments are conducted using the TUM GAID database, which is a large gait recognition database containing 3 050 recordings of 305 subjects in three variations.

In this paper, we exploit gradient histograms for person identification based on gait. A traditional and successful method for gait recognition is the Gait Energy Image (GEI). Here, person silhouettes are averaged over full gait cycles, which leads to a robust and efficient representation. However, binarized silhouettes only capture edge information at the boundary of the person. By contrast, the Gradient Histogram Energy Image (GHEI) also captures edges within the silhouette by means of gradient histograms. Combined with precise α-matte preprocessing and with a new part-based extension, recognition performance can be further improved. In addition, we show, that GEI can even be outperformed by directly applying gradient histogram extraction on the already bina-rized silhouettes. We run all experiments on the widely used HumanID gait database and show significant performance improvements over the current state of the art.

We present a new spatio-temporal representation for Gait Recognition, which we call Gradient Histogram Energy Image (GHEI). Similar to the successful Gait Energy Image (GEI), information is averaged over full gait cycles to reduce noise. Contrary to GEI, where silhouettes are averaged and thus only edge information at the boundary is used, our GHEI computes gradient histograms at all locations of the original image. Thus, also edge information inside the person silhouette is captured. In addition, we show that GHEI can be greatly improved using precise segmentation techniques (we use α-matte segmentation). We demonstrate great effectiveness of GHEI and its variants in our experiments on the large and widely used HumanID Gait Challenge dataset. On this dataset we reach a significant performance gain over the current state of the art.