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.

本研究提出了两种技术来改善局部标记数据集中的地标定位。第一种技术是顺序多任务，利用分类或回归任务的类标签引导未标记数据的局部标记定位。第二种是基于无监督学习的方法，通过模型预测图片上的等变地标来提高地标定位，本文在两个玩具数据集和四个实际数据集上进行实验，包括手和脸部， 并在只有 5％标记图像的条件下，跑过了之前在 AFLW 数据集上的最新 state-of-the-art 算法。