8 research outputs found
Spatial-Temporal Deep Embedding for Vehicle Trajectory Reconstruction from High-Angle Video
Spatial-temporal Map (STMap)-based methods have shown great potential to
process high-angle videos for vehicle trajectory reconstruction, which can meet
the needs of various data-driven modeling and imitation learning applications.
In this paper, we developed Spatial-Temporal Deep Embedding (STDE) model that
imposes parity constraints at both pixel and instance levels to generate
instance-aware embeddings for vehicle stripe segmentation on STMap. At pixel
level, each pixel was encoded with its 8-neighbor pixels at different ranges,
and this encoding is subsequently used to guide a neural network to learn the
embedding mechanism. At the instance level, a discriminative loss function is
designed to pull pixels belonging to the same instance closer and separate the
mean value of different instances far apart in the embedding space. The output
of the spatial-temporal affinity is then optimized by the mutex-watershed
algorithm to obtain final clustering results. Based on segmentation metrics,
our model outperformed five other baselines that have been used for STMap
processing and shows robustness under the influence of shadows, static noises,
and overlapping. The designed model is applied to process all public NGSIM
US-101 videos to generate complete vehicle trajectories, indicating a good
scalability and adaptability. Last but not least, the strengths of the scanline
method with STDE and future directions were discussed. Code, STMap dataset and
video trajectory are made publicly available in the online repository. GitHub
Link: shorturl.at/jklT0
CPP-Net: Context-aware Polygon Proposal Network for Nucleus Segmentation
Nucleus segmentation is a challenging task due to the crowded distribution
and blurry boundaries of nuclei. Recent approaches represent nuclei by means of
polygons to differentiate between touching and overlapping nuclei and have
accordingly achieved promising performance. Each polygon is represented by a
set of centroid-to-boundary distances, which are in turn predicted by features
of the centroid pixel for a single nucleus. However, using the centroid pixel
alone does not provide sufficient contextual information for robust prediction.
To handle this problem, we propose a Context-aware Polygon Proposal Network
(CPP-Net) for nucleus segmentation. First, we sample a point set rather than
one single pixel within each cell for distance prediction. This strategy
substantially enhances contextual information and thereby improves the
robustness of the prediction. Second, we propose a Confidence-based Weighting
Module, which adaptively fuses the predictions from the sampled point set.
Third, we introduce a novel Shape-Aware Perceptual (SAP) loss that constrains
the shape of the predicted polygons. Here, the SAP loss is based on an
additional network that is pre-trained by means of mapping the centroid
probability map and the pixel-to-boundary distance maps to a different nucleus
representation. Extensive experiments justify the effectiveness of each
component in the proposed CPP-Net. Finally, CPP-Net is found to achieve
state-of-the-art performance on three publicly available databases, namely
DSB2018, BBBC06, and PanNuke. Code of this paper will be released