#168: Ryan McMahan on climbing a ladder in VR with the March-and-Reach Technique

Ryan-McMahanRyan McMahan is Assistant Professor of Computer Science at the University of Texas at Dallas, where his research focuses on the effects of system fidelity for virtual reality (VR) applications and systems. He had an interest in VR training applications and was presenting at IEEE VR about a realistic ladder climbing technique called “march-and-reach.”

Climbing a ladder sounds in VR like it’d be a fairly straight-forward problem, but yet this interview shows all of the various nuances and design decisions that had to be made in order to both accurately replicate the feeling of virtually climbing a ladder, but also do it in a way where they could teach ladder safety.

There were previous ladder climbing techniques that would either be purely hand or feet-based methods for controlling vertical locomotion. Ryan decided to use the feet for controlling the vertical locomotion, and that there needed to be at least two points of contact at all time otherwise the person would fall off the ladder.

Part of why VR training can be so effective is that you can show people what a failure condition looks and feels like without putting someone’s physical safety in danger. They can make people fall of a ladder in VR and show that they’d break their legs, and having this level of realistic fear can actually help create episodic memories that can help people more effectively remember to always keep two points of contact while climbing a ladder.

There were other nuanced changes that they had to make in order to make the simulation more realistic. While you’re climbing a ladder, you’re holding on to the rungs of the ladder and leaning backwards so that when you look down you can see your feet. But yet if you’re walking in place and look down to see where your feet are, then you actually have to lean forward if the feet are tracked accurately, which would make people loose their balance and potentially fall down in real life. So Ryan had to create an offset the feet by 10 degrees forward so that people would be able to actually see their feet in VR while still maintaining their balance.

Here’s more information on the march-and-reach paper that Ryan presented at IEEE VR.

March-and-Reach: A realistic ladder climbing technique

In most 3D applications, travel is limited to horizontal movement. A few 3D travel techniques allow for vertical travel, but most of them rely on “magic” abilities, such as flying. We sought to develop a realistic vertical travel technique for climbing ladders. We have developed March-and-Reach, with which the user marches in place to virtually step on lower ladder rungs while reaching to virtually grab higher rungs. We conducted a within-subject study to compare March-and-Reach to two prior ladder-climbing techniques. Results indicate that users consider and treat March-and-Reach as the most realistic ladder climbing technique.

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