# KPMapNet: Keypoint Representation Learning for Online Vectorized High-Definition Map Construction

## TL;DR

KPMapNet improves the accuracy of creating high-definition maps for autonomous vehicles by learning keypoint representations and reducing errors in map construction.

## Contribution

KPMapNet introduces a new keypoint-based representation and training framework for vectorized HD map construction.

## Key findings

- KPMapNet achieves state-of-the-art performance with 75.1 mAP on nuScenes and 74.2 mAP on Argoverse2.
- The new representation preserves geometric features better than conventional methods.
- Visualizations confirm improved accuracy in map generation outcomes.

## Abstract

Vectorized high-definition (HD) map construction is a critical task in the autonomous driving domain. The existing methods typically represent vectorized map elements with a fixed number of points, establishing robust baselines for this task. However, the inherent shape priors introduce additional shape errors, which in turn lead to error accumulation in the downstream tasks. Moreover, the subtle and sparse nature of the annotations limits detection-based frameworks in accurately extracting the relevant features, often resulting in the loss of fine structural details in the predictions. To address these challenges, this work presents KPMapNet, an end-to-end framework that redefines the ground truth training representation of vectorized map elements to achieve precise topological representations. Specifically, the conventional equidistant sampling method is modified to better preserve the geometric features of the original instances while maintaining a fixed number of points. In addition, a map mask fusion module and an enhanced hybrid attention module are incorporated to mitigate the issues introduced by the new representation. Moreover, a novel point-line matching loss function is introduced to further refine the training process. Extensive experiments on the nuScenes and Argoverse2 datasets demonstrate that KPMapNet achieves state-of-the-art performance, with 75.1 mAP on nuScenes and 74.2 mAP on Argoverse2. The visualization results further corroborate the enhanced accuracy of the map generation outcomes.