POSITION: Open World 3D Scene CAD Recomposition

3D scene CAD recomposition aims to reconstruct a given scene by retrieving and assembling CAD models from a database, so as to accurately simulate the geometric properties and spatial arrangement of the original environment. Recent methods learn this task through training on limited scan-to-CAD annotation data, which hinders their generalization to diverse real-world scenes. In this paper, we propose POSITION, an open-world 3D scene CAD recomposition method to construct the 3D scene with CADs retrieved from an open-set database. POSITION is designed following a divide-and-conquer strategy. Firstly, we extract open-world multi-modal object representations from a captured 3D scene. Secondly, on top of the representations, we propose a coarse-to-fine retrieval method to retrieve CADs that are visually, geometrically and semantically match real objects. Thirdly, we present a physically plausible pose alignment method to adjust retrieved CAD models to maintain consistent geometry and layout with the observation. By decomposing the problem into well-defined subtasks, our approach achieves generalization across various scene types and scalable CAD databases without retraining or fine-tuning. Our approach demonstrates superior CAD recomposition performance on both the Scan2CAD and diverse real-world 3D scene datasets. Our project page: https://yangrongkun.github.io/position/.