OpenMask3D: Open-Vocabulary 3D Instance Segmentation
Authors: name: Ayça Takmaz, name: Elisabetta Fedele, name: Robert W. Sumner, name: Marc Pollefeys, name: Federico Tombari, name: Francis Engelmann

We introduce the task of open-vocabulary 3D instance segmentation.
Traditional approaches for 3D instance segmentation largely rely on existing 3D
annotated datasets, which are restricted to a closed-set of object categories.
This is an important limitation for real-life applications where one might need
to perform tasks guided by novel, open-vocabulary queries related to objects
from a wide variety. Recently, open-vocabulary 3D scene understanding methods
have emerged to address this problem by learning queryable features per each
point in the scene. While such a representation can be directly employed to
perform semantic segmentation, existing methods have limitations in their
ability to identify object instances. In this work, we address this limitation,
and propose OpenMask3D, which is a zero-shot approach for open-vocabulary 3D
instance segmentation. Guided by predicted class-agnostic 3D instance masks,
our model aggregates per-mask features via multi-view fusion of CLIP-based
image embeddings. We conduct experiments and ablation studies on the ScanNet200
dataset to evaluate the performance of OpenMask3D, and provide insights about
the open-vocabulary 3D instance segmentation task. We show that our approach
outperforms other open-vocabulary counterparts, particularly on the long-tail
distribution. Furthermore, OpenMask3D goes beyond the limitations of
close-vocabulary approaches, and enables the segmentation of object instances
based on free-form queries describing object properties such as semantics,
geometry, affordances, and material properties.