Visualization & Export

Data stored in NCore-specific dataformats can be visualized and exported using the tools described below.

Rolling-Shutter Point-Cloud to Camera Projections

The tool //tools:ncore_project_pc_to_img visualizes projections of point-clouds into camera images, applying sensor-specific rolling-shutter compensation. This verifies the extrinsics of the point-cloud sensor, the extrinsics of the cameras, the intrinsics of the cameras, as well as the trajectories of the rig.

Example invocation:

bazel run //tools:ncore_project_pc_to_img \
    -- \
    --sensor-id=lidar00 \
    --camera-id=camera01 \
    v4 \
    --component-group=<SEQUENCE_META.json>

Or with multiple component groups:

bazel run //tools:ncore_project_pc_to_img \
    -- \
    --sensor-id=lidar00 \
    --camera-id=camera01 \
    v4 \
    --component-group=<COMPONENT_GROUP0> \
    --component-group=<COMPONENT_GROUP1>

Point-to-camera projection on NV Hyperion data

Point-to-camera projection on Waymo-Open data

Point-to-camera projection on Physical-AI-AV data

Point-Cloud Export

The tool //tools:ncore_export_ply exports point-clouds into common .ply format, transforming points into different frames. Specifying --frame=world allows to visualize multiple frames in a common frame to verify the extrinsics of the point-cloud sensor, as well as the trajectories of the rig.

Example invocation:

bazel run //tools:ncore_export_ply \
    -- \
    --output-dir=<OUTPUT_FOLDER> \
    --sensor-id=lidar00 \
    --frame=world \
    v4 \
    --component-group=<COMPONENT_GROUP0> \
    --component-group=<COMPONENT_GROUP1>

Differently colored point clouds exported to a common world frame

Colored Point-Cloud Export

The tool //tools:ncore_export_colored_pc projects lidar point clouds onto a camera image to obtain per-point RGB colors, then exports the result as .ply files. This combines rolling-shutter-aware projection with PLY export to produce colored point clouds useful for visual inspection and downstream processing.

Example invocation:

bazel run //tools:ncore_export_colored_pc \
    -- \
    --output-dir=<OUTPUT_FOLDER> \
    --lidar-id=lidar00 \
    --camera-id=camera01 \
    v4 \
    --component-group=<SEQUENCE_META.json>

Option	Default	Description
--output-dir	(required)	Directory for output PLY files
--lidar-id	lidar_gt_top_p128	Lidar sensor to export
--camera-id	camera_front_wide_120fov	Camera sensor used for coloring
--device	cuda	Torch device (cuda or cpu)
--camera-pose	rolling-shutter	Projection pose mode (rolling-shutter, mean, start, end)
--point-cloud-space	world	Output coordinate space (world or sensor)
--lidar-return-index	0	Lidar ray bundle return index
--output-filepattern	frame-index	Filename pattern (frame-index or timestamps-us)
--start-frame	all	First frame index to export
--stop-frame	all	Past-the-end frame index
--step-frame	1	Frame step for downsampling

Camera Frame Export

The tool //tools:ncore_export_camera exports camera frames to image files for introspection, optionally encoding them as MP4 video.

Example invocation:

bazel run //tools:ncore_export_camera \
    -- \
    --output-dir=<OUTPUT_FOLDER> \
    --camera-id=camera00 \
    v4 \
    --component-group=<SEQUENCE_META.json>

Or with multiple component groups:

bazel run //tools:ncore_export_camera \
    -- \
    --output-dir=<OUTPUT_FOLDER> \
    --camera-id=camera00 \
    v4 \
    --component-group=<COMPONENT_GROUP0> \
    --component-group=<COMPONENT_GROUP1>