4,988 research outputs found
Improving Landmark Localization with Semi-Supervised Learning
We present two techniques to improve landmark localization in images from
partially annotated datasets. Our primary goal is to leverage the common
situation where precise landmark locations are only provided for a small data
subset, but where class labels for classification or regression tasks related
to the landmarks are more abundantly available. First, we propose the framework
of sequential multitasking and explore it here through an architecture for
landmark localization where training with class labels acts as an auxiliary
signal to guide the landmark localization on unlabeled data. A key aspect of
our approach is that errors can be backpropagated through a complete landmark
localization model. Second, we propose and explore an unsupervised learning
technique for landmark localization based on having a model predict equivariant
landmarks with respect to transformations applied to the image. We show that
these techniques, improve landmark prediction considerably and can learn
effective detectors even when only a small fraction of the dataset has landmark
labels. We present results on two toy datasets and four real datasets, with
hands and faces, and report new state-of-the-art on two datasets in the wild,
e.g. with only 5\% of labeled images we outperform previous state-of-the-art
trained on the AFLW dataset.Comment: Published as a conference paper in CVPR 201
Occlusion Coherence: Detecting and Localizing Occluded Faces
The presence of occluders significantly impacts object recognition accuracy.
However, occlusion is typically treated as an unstructured source of noise and
explicit models for occluders have lagged behind those for object appearance
and shape. In this paper we describe a hierarchical deformable part model for
face detection and landmark localization that explicitly models part occlusion.
The proposed model structure makes it possible to augment positive training
data with large numbers of synthetically occluded instances. This allows us to
easily incorporate the statistics of occlusion patterns in a discriminatively
trained model. We test the model on several benchmarks for landmark
localization and detection including challenging new data sets featuring
significant occlusion. We find that the addition of an explicit occlusion model
yields a detection system that outperforms existing approaches for occluded
instances while maintaining competitive accuracy in detection and landmark
localization for unoccluded instances
Automated multimodal volume registration based on supervised 3D anatomical landmark detection
We propose a new method for automatic 3D multimodal registration based on anatomical landmark detection. Landmark detectors are learned independantly in the two imaging modalities using Extremely Randomized Trees and multi-resolution voxel windows. A least-squares fitting algorithm is then used for rigid registration based on the landmark positions as predicted by these detectors in the two imaging modalities. Experiments are carried out with this method on a dataset of pelvis CT and CBCT scans related to 45 patients. On this dataset, our fully automatic approach yields results very competitive with respect to a manually assisted state-of-the-art rigid registration algorithm
- …