  In this work, we propose SAM3D, a novel framework that is able to predict
masks in 3D point clouds by leveraging the Segment-Anything Model (SAM) in RGB
images without further training or finetuning. For a point cloud of a 3D scene
with posed RGB images, we first predict segmentation masks of RGB images with
SAM, and then project the 2D masks into the 3D points. Later, we merge the 3D
masks iteratively with a bottom-up merging approach. At each step, we merge the
point cloud masks of two adjacent frames with the bidirectional merging
approach. In this way, the 3D masks predicted from different frames are
gradually merged into the 3D masks of the whole 3D scene. Finally, we can
optionally ensemble the result from our SAM3D with the over-segmentation
results based on the geometric information of the 3D scenes. Our approach is
experimented with ScanNet dataset and qualitative results demonstrate that our
SAM3D achieves reasonable and fine-grained 3D segmentation results without any
training or finetuning of SAM.
