The parameters of the sensor itself

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In general, unless the driver writer has chosen to expose this information, vendor and power won't be available. If it is available, it tends to be in a diagnostics message. For instance, in the Hokuyo driver urg_node here is where the information is populated: populateDiagnosticsStatus

Depending on the type sensor, resolution is available either in the sensor_msgs/CameraInfo or sensor_msgs/LaserScan