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 \
    -- \
    --source-id=lidar00 \
    --camera-id=camera01 \
    v4 \
    --component-group=<SEQUENCE_META.json>

Or with multiple component groups:

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

The --source-id flag accepts any point cloud source: a native point cloud ID (e.g. sfm_points), a lidar ID, or a radar ID.

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> \
    --source-id=lidar00 \
    --frame=world \
    v4 \
    --component-group=<COMPONENT_GROUP0> \
    --component-group=<COMPONENT_GROUP1>

The --source-id flag accepts any point cloud source (native, lidar, or radar).

Differently colored point clouds exported to a common world frame

Colored Point-Cloud Export

The tool //tools:ncore_export_colored_pc projects 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.

If the point cloud source already has an RGB attribute (e.g. COLMAP SfM points), the --use-source-rgb flag skips camera projection and uses the native colors.

Example invocation:

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

Option	Default	Description
--output-dir	(required)	Directory for output PLY files
--source-id	(first available)	Point cloud source to export (native, lidar, or radar ID)
--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-pc	all	First pc index to export
--stop-pc	all	Past-the-end pc index
--step-pc	1	Step for downsampling point clouds

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>