This paper presents KeypointNet, an end-to-end geometric reasoning framework to learn an optimal set of category-specific 3D keypoints, along with their detectors. Given a single image, KeypointNet extracts 3D keypoints that are optimized for a downstream task. We demonstrate this framework on 3D pose estimation by proposing a differentiable objective that seeks the optimal set of keypoints for recovering the relative pose between two views of an object. Our model discovers geometrically and semantically consistent keypoints across viewing angles and instances of an object category. Importantly, we find that our end-to-end framework using no ground-truth keypoint annotations outperforms a fully supervised baseline using the same neural network architecture on the task of pose estimation. The discovered 3D keypoints on the car, chair, and plane categories of ShapeNet are visualized at http://keypointnet.github.io/.

本文提出了KeypointNet，这是一个端到端的几何推理框架，用于学习一组最优的类别特定3D关键点及其检测器。 通过对一张单独图片，KeypointNet提取出用于下游任务优化的3D关键点，我们在3D姿势估计方面展示了这种框架，并提出了一个可微的目标，以寻求在两个对象视图之间恢复相对姿态的最佳关键点集。我们的模型在对象类别的不同视角和实例之间发现了几何和语义一致的关键点，重要的是，我们发现我们的端到端框架在不使用地面真值关键点注释的情况下胜过使用相同神经网络架构的完全监督基线在姿势估计任务上，在ShapeNet的汽车，椅子和飞机类别上可视化出发现的3D关键点。

通过端到端几何推理发现潜在的三维关键点