VI-Rig — 4 IMUs + 3 cameras

Three global-shutter cameras and four IMUs on one frame, recorded in front of an AprilGrid. The Quickstart uses this set.

Hub folder: calibench-vi/datasets → virig-4imus-3cams
Licence: CC BY-NC 4.0, gated; commercial use on request. See Licence and access.
Results: benchmark results · worked example

The VI-Rig: the Blackfly camera at top right, the T265 at bottom right and the IMUs on the plate

The rig

Rates are measured from the bags. Shutter: every camera here is global shutter.

Sensor	Type	Rate	Image size	ROS topic
FLIR Blackfly S BFS-U3-16S2M	camera, standard lens	30 Hz	720×540 (2×2 binned)	`/blackfly/image_raw`
RealSense T265, left	camera, fisheye (about 163°)	30 Hz	848×800	`/t265/fisheye1/image_raw`
RealSense T265, right	camera, fisheye (about 163°)	30 Hz	848×800	`/t265/fisheye2/image_raw`
Xsens MTi-100	IMU	400 Hz	–	`/imu/data`
MicroStrain 3DM-GX3-25	IMU	500 Hz	–	`/gx3_25/data`
MicroStrain 3DM-GX3-35	IMU	100 Hz	–	`/gx3_35/imu/data`
RealSense T265 IMU (BMI055)	IMU	200 Hz	–	`/t265/imu`

Board: AprilGrid, 6×6 tags of family t36h11, tag size 88 mm, spacing 0.3 of the tag size. The target file april.yaml is in the folder.
Board shape: the printed board is not flat (about 2.4 mm rms). Our runs estimate its shape; see Why calibrate the board shape.
Drivers: we recorded with these ROS drivers.
More on the T265: device page.

Recordings

Count: 10 ROS1 bags, virig_4imus_3cams_april_01.bag to virig_4imus_3cams_april_10.bag.
Length: 131 to 161 s each, 24 minutes in total.
Size: 6.9 to 8.5 GB each, 76 GB in total.

Time-offset sweep

The folder also holds tga-sweep/: 11 versions of recording 01, cut to a shorter window, with the T265 accelerometer delayed by a known amount (−50 to +50 ms). They test whether a tool can find the delay between gyroscope and accelerometer ( $t_{ga}$ ). Each copy is 3.3 GB. A README, the MVIS calibration used for the correction and a provenance.json are beside them. See Why calibrate t_ga.

Download

Accept the terms on the Hub page and set HF_TOKEN to a read token from your Hugging Face settings (or run hf auth login once, after pip install huggingface_hub). Then either:

# with MVIS: checks size and SHA-256, saves to $MVIS_DATASETS/mvis_4imus_3cams/
mvis datasets list --dataset mvis_4imus_3cams
mvis datasets download --select mvis_4imus_3cams/april_01   # one recording, 6.9 GB
mvis datasets download --dataset mvis_4imus_3cams           # all 10, 76 GB

# with the Hugging Face CLI: the 10 recordings and the board file, without the sweep
hf download calibench-vi/datasets --repo-type dataset \
  --include "virig-4imus-3cams/virig_*.bag" "virig-4imus-3cams/april.yaml" \
  --local-dir ./calibench

Results

We ran MVIS and Kalibr on every recording, and Basalt on the camera-only runs (batch 2026-11-10a). The results page shows every value and its spread.

Run	Recordings solved
Camera only. Kalibr: the 3 cameras together. MVIS and Basalt: the Blackfly alone and the T265 pair, so no baseline to the Blackfly	MVIS 10 of 10 · Kalibr 10 of 10 · Basalt 10 of 10
Camera + IMU, 3 cameras + 4 IMUs	MVIS 10 of 10 · Kalibr 10 of 10 · Basalt not run (one IMU per run)

A few MVIS values from the camera + IMU runs. Each is the median over the 10 recordings, ± the standard deviation between recordings. This shows how well MVIS repeats, not that it is right.

Blackfly focal length $f_x$ : 448.30 ± 0.61 px
Lever arm of the GX3-25 from the Xsens: 131.31 ± 0.20 mm
Time offset of the T265 IMU to the Xsens: 2.83 ± 0.21 ms
Reprojection error, median: 0.35 px (Blackfly), 0.23 and 0.24 px (T265 pair)

The worked example shows one full run with its config.

Sensor order in the results files

The reference results in calibench-vi/results hold one file per tool, batch and run (for example MVIS/2026-11-10a/T6.json) and the configs behind them in configs/T6/ (camera + IMU) and configs/T6c/ (camera only). Kalibr and MVIS name the sensors in the same order. The base IMU is the one the other sensors are referred to.

Sensor	Blackfly	T265 left	T265 right	Xsens MTi-100	GX3-25	GX3-35	T265 IMU
Kalibr	cam0	cam1	cam2	imu0	imu1	imu2	imu3
MVIS	cam0	cam1	cam2	base IMU	aux IMU 1	aux IMU 2	aux IMU 3

Run it yourself

Start here: the worked example has the camera + IMU config we ran.
Steps: a camera-only run first (mvis cam -c <config>), then camera + IMU (mvis cam-imu -c <config>). See Camera-only calibration and Camera–IMU calibration.

Cite

Please cite Calibench and the MVIS paper. The BibTeX is on the overview page.