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The Raw Messages panel displays the full structured content of any topic as an expandable JSON tree. It works with every message type — including custom schemas and topics that do not match any specialized panel. This makes it the universal fallback for inspecting data and the primary tool for debugging and schema exploration.

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When It Is Used

The Raw Messages panel is assigned in two situations:
  1. Fallback assignment — When a topic’s schema and name do not match any specialized panel (Image, Point Cloud, Plot, Map, Log, Gauge, or State), it is automatically assigned to the Raw Messages panel.
  2. Explicit inspection — You can open any topic in the Raw Messages panel to inspect its full message structure, regardless of whether it also appears in a specialized panel.

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Features

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JSON Tree View

Messages are displayed as a collapsible tree structure. Each field in the message is shown with its name, type, and value. Nested objects and arrays can be expanded or collapsed to navigate complex message hierarchies. 
message
├── header
│   ├── stamp: { sec: 1706123456, nsec: 789000000 }
│   ├── frame_id: "base_link"
│   └── seq: 42
├── data: [0.123, -0.456, 9.81, ...]
├── width: 1024
├── height: 768
└── fields: [...]

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Value Inspection

Click on any field to see its full value. This is especially useful for:
  • Large arrays — Point cloud data fields, image buffers, and other large arrays show a summary by default. Click to see individual elements.
  • Nested objects — Expand deeply nested structures to trace through complex message types.
  • Numeric precision — See the full floating-point value without truncation.

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Schema Display

The panel shows the message schema at the top, including:
PropertyDescription
Schema nameThe full schema identifier (e.g., sensor_msgs/Imu, foxglove.PointCloud)
Topic nameThe topic path (e.g., /imu/data)
EncodingThe message encoding format (protobuf, CDR, JSON)

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Timeline Synchronization

Like all panels, the Raw Messages panel is synchronized with the shared timeline. As you seek or step through the recording, the panel updates to show the message content at the current timestamp.

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Search and Filter

For messages with many fields, use the search function to find specific field names or values. This helps navigate large message types without manually expanding the entire tree.

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Common Use Cases

Schema exploration

Inspect the structure of unfamiliar message types to understand what fields are available and how data is organized.

Debugging

Check individual field values to diagnose issues with sensor data, transforms, or configuration messages.

Custom message types

View custom or proprietary message schemas that do not have a dedicated panel type.

Data validation

Verify that specific fields contain expected values at specific timestamps.
The Raw Messages panel works with any topic, regardless of schema. If you encounter an unrecognized message type, this panel lets you explore its contents without any additional configuration.

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Reading Complex Messages

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Point Cloud Fields

For sensor_msgs/PointCloud2 messages, the tree shows the field descriptors, point data layout, and a summary of the point count. Expand the fields array to see each field’s name, offset, datatype, and count.

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Transform Messages

For tf2_msgs/TFMessage, the tree shows each transform in the message with its parent frame, child frame, translation, and rotation quaternion. This is useful for debugging transform tree issues.

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Nested Arrays

Large arrays (such as image pixel data or point coordinates) display a count and summary. Individual elements can be accessed by expanding the array node and scrolling to the desired index.
Use the Raw Messages panel alongside specialized panels to cross-reference data. For example, if a point cloud looks wrong in the 3D viewer, open the same topic in Raw Messages to check the field layout and point count.