Hardware

Sensor Head Specification

For our dataset, we use the following:

Example Zed Mini image stream from Tunnel Circuit:

Multiple different depth camera systems were tested before I decided that the Zed Mini was the best option for our requirements.
The depth estimation backbone is passive stereo matching. This seems like an odd choice of camera to send into a dark cave/mine without natural illumination. However, with our onboard active illumintation system we were able to achieve good depth estimation performance underground.
Since this is the primary sensor for artifact recognition, one of the primary requirements was having good quality RGB imagery, and in my comparisons with the ZED's RealSense counterparts, I believe the quality of the RGB cameras on the Zed outperform it's alternatives.
The Zed mini is also able to better handle dust, which was an important factor in our decision. Active illumination in a dust-filled environment brings interesting challenges with visual degradation of imagery. I am very happy with the performance of this sensor in these environments. I suspect that the choice of sensor along with the fact that this is a rolling shutter system, makes individual dust particles less prominent.
Lastly, the icing on the cake - the stereo camera calibration tool. Having a tool this easy to use in the field is invaluable. Hats off to the Stereolabs team for building such an intuitive calibration software. As someone who has spent the last 3 years calibrating stereo cameras, you have my respect and gratitude.

This camera appears to be somewhat of a favourite among the SubT teams. I noticed them on numerous platforms at Tunnel Circuit and it isn't surprising. I have used the Boson 320 in the 50deg and 92deg variants and they are excellent devices that require very little in the way of compute or set-up to get running.
For this dataset, we use the FLIR Boson 320 2.3mm 92 degree HFOV model. We use the 60Hz variant and record our data in both 8-bit AGC as well as raw 16-bit.
The 320 variant seemed sufficient for our task; the 640 must be much nicer but it is also significantly more expensive.

There's not much to say about these lights. They're lights. They're bright lights. They're very bright lights.