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ROS2 Sensor Messages

CameraInfo

sensor_msgs.CameraInfo — camera calibration and metadata.

Intrinsic matrix k (3×3, 9 elements), rectification r (3×3), projection p (3×4, 12 elements), distortion d (variable length).

CompressedImage

sensor_msgs.CompressedImage — JPEG / PNG / etc. encoded image.

Same construction model as :class:Image: bulk data is copied once at build time, then exposed read-only via :class:BorrowedBuf.

data property 

data: BorrowedBuf

Zero-copy view of the encoded image bytes.

format property 

format: str

Codec identifier — e.g. "jpeg", "png".

Image

sensor_msgs.Image — uncompressed raster image.

Construction copies the bulk data payload once into the CDR buffer (GIL released during the copy). Read-side data returns a :class:BorrowedBuf exposing the in-buffer payload via the buffer protocol — zero-copy for np.frombuffer, memoryview, etc.

Example

::

import numpy as np
pixels = np.zeros((720, 1280, 3), dtype=np.uint8)
img = Image(
    header=Header(stamp=Time(1, 0), frame_id="cam"),
    height=720, width=1280, encoding="rgb8",
    is_bigendian=0, step=1280 * 3,
    data=pixels,
)

# Zero-copy view (Py 3.11+ / non-abi3):
arr = np.frombuffer(img.data, dtype=np.uint8).reshape(720, 1280, 3)
# On abi3-py38: arr = np.frombuffer(img.data.view(), dtype=np.uint8).reshape(720, 1280, 3)

data property 

data: BorrowedBuf

Zero-copy view of the pixel data.

step property 

step: int

Row stride in bytes.

cdr_view 

cdr_view() -> BorrowedBuf

Zero-copy view of the full CDR buffer (header + payload).

to_bytes 

to_bytes() -> bytes

Return the full CDR buffer as bytes (one copy).

Imu

sensor_msgs.Imu — orientation, angular velocity and linear acceleration each with a 3×3 row-major covariance matrix.

Covariance matrices are exposed as 9-element list[float] (not numpy) since they're small fixed-size and Python list semantics are cleaner for this scale.

sensor_msgs.NavSatStatus — GNSS fix status + service bitmask.

Status (i8): -1 NO_FIX, 0 FIX, 1 SBAS_FIX, 2 GBAS_FIX.

Service bitmask (u16): 0x01 GPS, 0x02 GLONASS, 0x04 COMPASS, 0x08 GALILEO.

CdrFixed — 4 bytes payload (i8 + pad + u16, position-dependent alignment within composite messages).

sensor_msgs.NavSatFix — GNSS position fix with covariance.

position_covariance_type constants: 0 = UNKNOWN, 1 = APPROXIMATED, 2 = DIAGONAL_KNOWN, 3 = KNOWN.

PointField

sensor_msgs.PointField — descriptor of one field within a :class:PointCloud2's packed point layout.

datatype follows the ROS 2 spec: 1 INT8, 2 UINT8, 3 INT16, 4 UINT16, 5 INT32, 6 UINT32, 7 FLOAT32, 8 FLOAT64.

PointCloud2

sensor_msgs.PointCloud2 — packed point cloud with :class:PointField descriptors.

data is a packed byte array of width × height points, each point_step bytes wide. Field offsets/types come from the fields list (set at construction or returned by the property).

Example

::

fields = [
    PointField(name="x", offset=0,  datatype=7, count=1),  # float32
    PointField(name="y", offset=4,  datatype=7, count=1),
    PointField(name="z", offset=8,  datatype=7, count=1),
    PointField(name="i", offset=12, datatype=2, count=1),  # uint8
]
pc = PointCloud2(
    header=Header(stamp=Time(1, 0), frame_id="lidar"),
    height=1, width=131072, fields=fields,
    is_bigendian=False, point_step=13, row_step=13 * 131072,
    data=byte_buffer, is_dense=True,
)

data property 

data: BorrowedBuf

Zero-copy view of the packed point data.

RelativeHumidity

sensor_msgs.RelativeHumidity — relative humidity measurement (0–1 ratio).

Relative humidity as a dimensionless ratio in [0, 1] with a variance field.

Temperature

sensor_msgs.Temperature — temperature reading (typically Celsius) with scalar variance.

TimeReference

sensor_msgs.TimeReference — UTC / GPS / PPS time reference with a source label.