Dibuli Prism-A4L

Demo and values

1000 µs2000 µs

Multi-sensor capture box from Dibuli with four global-shutter fisheye cameras and a 6-axis IMU, solved from the maker's public example data at two exposures.

The 3D scene MVIS recovered from the maker's example data, 1,000 µs exposure.

Reprojection median0.18 px

cam0–cam1 baseline85.3 mm

cam0 td+2.06 ms

cam0 lever arm71.6 mm

Reprojection is how far, in pixels, the detected corners lie from where the solve puts them. td is the camera–IMU time offset, and the lever arm is the camera–IMU position offset.

No independent reference on this page. These values show what MVIS solved, not how close they are to the truth.

Calibration process

The path of the rig around the board, as MVIS solved it. To explore it:

• Press Play or drag the bar to follow the path.
• Use the view buttons to change the view.
• Pick a camera card to put that camera on the frustum, the pyramid that shows its view.

Each card draws the board from the solved pose, with the corners MVIS detected. We publish no camera images.

Solved rig

The solved rig in 3D, to scale. Tap a sensor to see its values. In full screen you can rotate and zoom. Grid squares are 20 mm.

3DFrontTopSide+−

To scale, from above and the front

From above

From the front

Camera	Lever x, y, z (mm)	Distance (mm)	log(R) (rad)	td (ms)	Field of view
cam0	+63.9, −26.2, +19.0	71.6	[−1.217, +1.234, −1.195]	+2.06	168° × 131°
cam1	−12.7, −63.7, +20.5	68.1	[−0.005, +2.221, −2.213]	+2.06	167° × 131°
cam2	+64.8, +48.6, +19.8	83.4	[−1.216, +1.217, −1.200]	+2.09	167° × 130°
cam3	−13.1, +85.5, +20.6	88.9	[−1.564, +0.001, +0.006]	+2.12	168° × 130°

Solved by MVIS. Lever arms (camera–IMU position offsets) are in the IMU frame. Rotation is log(R), camera in the IMU frame.

Specifications

Published by the maker
Cameras	Up to 4 global-shutter, 1280×1024 MJPEG, 1 to 30 fps
Sync	PPS
Measured in these recordings
IMU	6-axis at 797.7 Hz in these recordings
Lens	Fisheye, EUCM fit
Calibrated field of view	cam0 168° × 131° · cam1 167° × 131° · cam2 167° × 130° · cam3 168° × 130°

Dataset

Recordings	2 camera + IMU bags at 1,000 and 2,000 µs exposure, about 450 MB each
Source	Maker's public download, files.dibuli.com
Board	AprilGrid 8×8, tag 70 mm, spacing 0.3
Licence	CC BY-NC 4.0; commercial use by request
Hosted	Calibench community, dibuli-prism-a4l/ (access by automatic approval)

AprilGrid 8 × 8, 707 × 707 mm. Standard pattern, to scale

Detailed results

Lens Calibrated field of view

Calibrated field of view, horizontal × vertical. cam0: 168° × 131°, corners reach 93° from the axis · cam1: 167° × 131°, corners reach 97° from the axis · cam2: 167° × 130°, corners reach 91° from the axis · cam3: 168° × 130°, corners reach 97° from the axis

cam0 cam1 cam2 cam3

We read these from the calibrated lens fit at the image edges, through the principal point (where the optical axis meets the image). ~ marks an axis past where the corners reached, so the fit is extrapolated there. Past the fit means an edge lies beyond where the fit holds, so we give no value.

IMU Gyro–accel time offset t_ga −0.09 ms

Each bar shows a scale as its deviation from 1. IMU model: kalibr. t_ga, the time offset between the gyroscope and accelerometer channels: −0.09 ± 0.02 ms.

Gyro scale x+0.84 %

Gyro scale y+0.94 %

Gyro scale z−0.42 %

Accel scale x+0.46 %

Accel scale y+0.41 %

Accel scale z−0.14 %

−8 %0+8 %

Timing cam0 td +2.06 ms

The time offsets, to scale. td is the camera–IMU time offset, with t_imu = t_cam + td.

Full results Every solved parameter

Rotation is log(R) in rad, camera in the IMU frame.

Parameter	MVIS
cam0
fx px	462.89
fy px	462.45
cx px	637.11
cy px	523.22
alpha	0.65834
beta	1.07644
Lever x mm	+63.90
Lever y mm	−26.16
Lever z mm	+19.00
log(R) rad	[−1.2169, +1.2344, −1.1950]
td ms	+2.063
Reprojection px	0.304
cam1
fx px	463.25
fy px	462.79
cx px	622.48
cy px	465.02
alpha	0.66073
beta	1.06531
Lever x mm	−12.70
Lever y mm	−63.68
Lever z mm	+20.52
log(R) rad	[−0.0046, +2.2214, −2.2130]
td ms	+2.064
Reprojection px	0.318
cam2
fx px	464.90
fy px	464.43
cx px	603.71
cy px	507.10
alpha	0.65709
beta	1.08000
Lever x mm	+64.79
Lever y mm	+48.63
Lever z mm	+19.79
log(R) rad	[−1.2160, +1.2165, −1.2003]
td ms	+2.087
Reprojection px	0.261
cam3
fx px	463.89
fy px	463.91
cx px	637.27
cy px	488.19
alpha	0.65989
beta	1.07393
Lever x mm	−13.08
Lever y mm	+85.54
Lever z mm	+20.58
log(R) rad	[−1.5643, +0.0005, +0.0058]
td ms	+2.122
Reprojection px	0.227
IMU
t_ga ms	−0.09 ± 0.02

Limits

• No independent reference on this page. These values show what MVIS solved, not how close they are to the truth.
• td changes with exposure. The exact slope is still open.

How it was run

• EUCM camera model, Kalibr IMU model, t_ga estimated, camera intrinsics free, seeded from the camera-only fit. Batch of 2026-11-03. This solve uses physical camera 1 as its base, so cam0 and cam1 on this page are physical cam1 and cam0.