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wtf is dalaran?

flaminis/dalaran — explained in plain English

Analysis updated 2026-08-14

941RustAudience · developerComplexity · 3/5LicenseSetup · moderate

TL;DR

Dalaran is a free, self-hosted tool for robotics teams to record, replay, and visualize sensor data like camera images, LiDAR, and IMU readings all on a synchronized timeline.

Mindmap

mindmap
  root((repo))
    What it does
      Records robot sensor data
      Replays on shared timeline
      Visualizes live or saved
    Tech stack
      Rust
      Python SDK
      C++ SDK
    Use cases
      Log data from ROS 2
      Render occupancy grids
      Share recording packages
    Audience
      Robotics teams
      Sensor engineers
      Self-hosted users
    Key features
      ROS 2 bridge
      URDF coordinate handling
      Dalaran doctor command

Code map

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Why would anyone build with this?

REASON 1

Record and replay synchronized multi-sensor robot sessions for debugging.

REASON 2

Visualize live ROS 2 topic data or replay existing rosbag2 recordings.

REASON 3

Package a recording with its layout and assets to share with a teammate.

REASON 4

Render occupancy grids and costmaps from navigation stacks with proper cost categories.

What's in the stack?

RustPythonC++ROS 2

How it stacks up

flaminis/dalaranhalfrgrd/flyline514-labs/dnsglobe
Stars941952910
LanguageRustRustRust
Setup difficultymoderatemoderateeasy
Complexity3/52/52/5
Audiencedeveloperdeveloperops devops

Figures from each repo's GitHub metadata at analysis time.

How do you spin it up?

Difficulty · moderate Time to first run · 30min

Requires a working ROS 2 environment for live robot integration and a URDF model for advanced coordinate transform features.

Free to use, modify, and distribute including for commercial purposes, with attribution, you must disclose modifications and cannot hold the authors liable.

Wtf does this do

Dalaran is a tool for robotics teams who need to record, replay, and visualize what their robots see and do. It handles many kinds of sensor data at once: ROS 2 message topics, LiDAR point clouds, camera images, IMU readings, and coordinate transforms. You log all of this from your robot, a simulator, or an offline data pipeline, and Dalaran stores it on a shared timeline so every sensor stays in sync when you replay it. The software is built in Rust and offers SDKs for Python, Rust, and C++. Installing the Python package gives you the viewer application as well. The viewer can open saved recordings, display a live stream from a running robot, or serve a web-based viewer over a network. Recordings are saved as .dlr files, and saved viewer layouts are .dbl files. A single command, dalaran doctor, checks your environment and reports problems in plain language, which helps when something in your setup is broken. Several features are aimed directly at robotics workflows. A high-level logging API knows about robot structure, so you can pass joint states and a URDF model and let it handle coordinate conversions for you. A ROS 2 bridge subscribes to live topics or replays rosbag2 recordings, and you can register custom message types without modifying the core software. There are helpers for standard axis conventions, because mismatched coordinate frames are a common source of broken visualizations. Occupancy grids and costmaps from common navigation stacks are rendered with their proper cost categories, not flattened into generic images. Dalaran can also read existing .rrd recordings produced by Rerun, the project it forked from, without any conversion step. The on-disk storage format is unchanged, so data loads directly. Saved viewer layouts from those older recordings may not fully resolve yet, though the data itself comes through. The project is Apache-2.0 licensed and designed to run entirely on your own machines, with no dependency on a hosted service. You can package a recording, its layout, referenced assets, and metadata into a single .dlrpack` file to hand to a colleague. The full README is longer than what was shown.

Yoink these prompts

Prompt 1
Help me install the Dalaran Python package and run dalaran doctor to verify my robotics environment is set up correctly.
Prompt 2
Write a Python script using the Dalaran SDK to log LiDAR point clouds and camera images from my robot onto a shared timeline.
Prompt 3
Set up the Dalaran ROS 2 bridge to subscribe to live sensor topics and stream them into the Dalaran viewer.
Prompt 4
Show me how to pass joint states and a URDF model to Dalaran so it handles coordinate transforms for my robot visualization.
Prompt 5
Create a .dlrpack file that bundles my saved recording, viewer layout, and referenced assets so I can share it with a colleague.

Frequently asked questions

wtf is dalaran?

Dalaran is a free, self-hosted tool for robotics teams to record, replay, and visualize sensor data like camera images, LiDAR, and IMU readings all on a synchronized timeline.

What language is dalaran written in?

Mainly Rust. The stack also includes Rust, Python, C++.

What license does dalaran use?

Free to use, modify, and distribute including for commercial purposes, with attribution, you must disclose modifications and cannot hold the authors liable.

How hard is dalaran to set up?

Setup difficulty is rated moderate, with roughly 30min to a first successful run.

Who is dalaran for?

Mainly developer.

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