Cameras

Views

Each camera stream is one channel of foxglove.CompressedVideo, foxglove.CompressedImage or foxglove.RawImage messages, declared in the overlay’s views array with the role a media message cannot carry:

"primary_view": "/cam/front",
"views": [
  {"channel": "/cam/front",      "role": "front",      "label": "Front wide"},
  {"channel": "/cam/front_left", "role": "front_left", "label": "Front left"}
]

Field	Type	Required	Rule
`channel`	string	yes	The camera’s channel. MUST exist and carry an accepted media message.
`role`	string	yes	lower_snake_case (`^[a-z0-9_]+$`), unique in the recording. See Roles.
`label`	string	no	A human-readable name.

Top-level primary_view SHOULD name the recording’s default view and, when present, MUST name a declared view’s channel. It MAY be omitted for a LiDAR-only recording.
Keep multi-camera rigs as separate views. Do not pre-stitch a mosaic: it destroys per-camera geometry and cannot be undone.

Roles

role is free text. These canonical roles have a defined meaning; an unrecognised role is accepted, with a warning, and kept as a label, so an unusual rig is never blocked.

Rig	Canonical roles
Vehicle surround	`front`, `front_left`, `front_right`, `rear`, `rear_left`, `rear_right`, `left`, `right`, `top`, `bottom`, `left_repeater`, `right_repeater`, `left_pillar`, `right_pillar`, `vehicle_view`, `surround_view`, `range_view`
Overhead / site	`overhead_1` … `overhead_6`
Robot	`wrist_left`, `wrist_right`
Head-worn	`ego` (the head camera), `slam_left`, `slam_right`, `eye_left`, `eye_right`
Off-body	`external_1`, `external_2`, … (any positive number, no leading zero)

A camera that is not on the body (fixed in the world, e.g. a third-person view of a robot or a person) uses external_<n>. Any kind of body MAY have external cameras.
On a robot, the main body or head camera is usually front (or ego on a humanoid or head-worn rig); a camera on the end effector is wrist_left or wrist_right.
range_image and range_image_rgb are reserved: views with these roles are generated from LiDAR at ingest. Do not declare them.

Intrinsics

Publish each camera’s intrinsics as a foxglove.CameraCalibration message (not declared in the overlay):

Field	Value
`frame_id`	the camera’s frame, matching its image messages and its transform
`width`, `height`	image size in pixels
`K`	3×3 intrinsic matrix, row-major
`distortion_model`, `D`	only if the images are not rectified

Intrinsics are per camera; cameras on one rig routinely differ. Omitting D means the images are rectified. Do not publish a zero D for unknown distortion: it makes “rectified” and “distortion unknown” indistinguishable.

Encodings

Schema	Accepted `format` / `encoding`
`foxglove.CompressedVideo`	`h264` (preferred), `h265`
`foxglove.CompressedImage`	`jpeg`, `png`, `webp`
`foxglove.RawImage`	`rgb8`, `bgr8`, `mono8`

Compressed video

foxglove.CompressedVideo data follows the Foxglove definition: Annex B byte stream, each message exactly one frame, keyframes carrying their parameter sets. In addition:

No B-frames. Decode order MUST equal presentation order, because the video is rebuilt by concatenating message payloads in log_time order. Encode with -bf 0 (ffmpeg) for both h264 and h265. An h265 stream with B-frames is rejected.
If your source is h265 with B-frames, re-encode with -bf 0 (to h264 or h265) or publish a foxglove.CompressedImage sequence instead.

Image sequences

CompressedImage and RawImage sequences are assembled into video using the message timestamps, so irregular frame intervals are preserved.

Nomadic MCAP Specification

Examples

Views

Roles

Intrinsics

Encodings

Compressed video

Image sequences

​Views

​Roles

​Intrinsics

​Encodings

​Compressed video

​Image sequences

Views

Roles

Intrinsics

Encodings

Compressed video

Image sequences