Visual localization is an important part of many interesting applications, including robotics. The dominant localization strategy is to estimate the camera pose from 2D-3D matches between 2D pixel positions and 3D points. Yet, such approaches can be quite memory intensive and can lead to privacy risks. An interesting alternative to point-based matches is to use higher-level primitives for pose estimation. Consequently, this work investigates using correspondences between 2D and 3D bounding boxes for camera pose estimation. The resulting scene representation is compact and poses fewer privacy risks. In this setting, there are typically orders of magnitude fewer matches available compared to classical feature-based methods. In addition, the available correspondences are significantly more noisy. We investigate multiple strategies based on converting bounding box correspondences to point correspondences and propose a novel and simple 2-point camera absolute pose solver (DP2P) that exploits the fact that the depths of the objects can be approximated from the sizes of their bounding boxes.

We study the influence of image interpolation algorithms on local feature detectors operating on a scale pyramid, focusing on the Difference-of-Gaussian, as used in SIFT. We show that commonly used implementations, such as in OpenCV and Kornia, are neither rotational nor scale equivariant. We present a simple solution and demonstrate its positive influence on the downstream image matching tasks. The implementation of the method has been accepted in standard libraries OpenCV [1] and Kornia [2].