Object Pose Estimation Based on Multi-precision Vectors and Seg-Driven PnP

Abstract

Object pose estimation based on a single RGB image has wide application potential but is difficult to achieve. Existing pose estimation involves various inference pipelines. One popular pipeline is to first use Convolutional Neural Networks (CNN) to predict 2D projections of 3D keypoints in a single RGB image and then calculate the 6D pose via a Perspective-n-Point (PnP) solver. Due to the gap between synthetic data and real data, the model trained on synthetic data has difficulty predicting the 6D pose accurately when applied to real data. To address the acute problem, we propose a two-stage pipeline of object pose estimation based upon multi-precision vectors and segmentation-driven (Seg-Driven) PnP. In keypoint localization stage, we first develop a CNN-based three-branch network to predict multi-precision 2D vectors pointing to 2D keypoints. Then we introduce an accurate and fast Keypoint Voting scheme of Multi-precision vectors (KVM), which computes low-precision 2D keypoints using low-precision vectors and refines 2D keypoints on mid- and high-precision vectors. In the pose calculation stage, we propose Seg-Driven PnP to refine the 3D Translation of poses and get the optimal pose by minimizing the non-overlapping area between segmented and rendered masks. The Seg-Driven PnP leverages 2D segmentation trained on real images to improve the accuracy of pose estimation trained on synthetic data, thereby reducing the synthetic-to-real gap. Extensive experiments show our approach materially outperforms state-of-the-art methods on LM and HB datasets. Importantly, our proposed method works reasonably well for weakly textured and occluded objects in diverse scenes.