SAM 3D Selector

This project aims to convert users' multi-view annotated 2D image segmentations (via segment-anything) to the corresponding 3D point cloud/mesh.

Just several coordinate space conversions, no other complicated methods (welcome to leave your suggestions).

I initially implemented this project to help the point selection process for my other project SPIDR, where I manually select points for deformations/animations.

I want to use SAM to automate this process, however, my current solution are still far from the perfection.

👇Point cloud

👇Mesh

Dependencies

• SAM
  • Assume you set up SAM at ./segment-anything and download checkpoints at ./segment-anything/checkpoints
  • You can change to other location in app.py
• open3d >= 0.16
• python-opencv

How to Use

Annotate keypoints on the displayed image by clicking with the left mouse button.

Here are some control keys under openCV GUI:

Key	Action
m	Toggle between foreground and background keypoint annotation
z	Undo the last keypoint
s	Save the mask and keypoints
n	Go to the next frame
p	Go to the previous frame
r	Reset the image
c	Crop the point cloud
u	Union the point cloud
x	Intersect the point cloud
e	Export the masked point cloud (compatible with MeshLab)
q	Exit the program
k	Switch the selection mode
a	Add the current frame mask for multi-frame selection

The slider on the bottom controls the depth of the selected 3D points. The percentage is related to the size of the object bound box.

Input Arguments

• --image: Path to the input image (default: "demo.png").
• --wo_sam: Flag to not use the SAM model for mask prediction.
• --save_path: Path to save the mask and keypoints (default: "output/").
• --dataset_path: Path to a nerf_synthetic-like image folder (default: "").
• --dataset_split: Dataset split (default: "test").
• --dataset_skip: Number of frames to skip in the dataset (default: 10).
• --pcd_path: Path to the 3D point cloud file (default: "").
• --mesh_path: Path to the 3D mesh file (default: "").

Example

python app.py --dataset_path data/nerf_synthetic/lego --pcd_path data/3d_rep/lego_pcd.ply

The example point cloud & mesh can be downloaded from the following links:

# point cloud
gdown --fuzzy https://drive.google.com/file/d/1z9zuTKNbLFp6DOLfJN42kpUO0_ECCvy_/view?usp=share_link -O data/3d_rep/lego_pcd.ply
# mesh
gdown --fuzzy https://drive.google.com/file/d/17rqjWihUJshzt_Hc1YIJ8J5GNfr5WBJf/view?usp=share_link -O data/3d_rep/lego_mesh.obj

Observations

• The SAM's segmentations are amazing, but not perfect. You can often see the boundary are not included in the mask (alot manual-tuning).

• Keypoint prompting's accuracy can be improved a lot with recurrent mask inputs mask_input=logits.

• 3D geometry consistency is still too difficult for SAM. We cannot easily wrap the mask to the new frame.

• Automatic combining multi-frame selections is difficult:

  • small components can be easily occluded by other parts: cannot simply union or intersect.
  • intersection on co-visible masks? --> works not well.