~ 4:30 Minute Read.

This is the sec­ond post in a se­ries about the vir­tu­al re­al­i­ty es­cape room project I did to­geth­er with Daniel Bo­gen­rieder and Rox­anne Low at the Uni­ver­si­ty of Kon­stanz.

Re­di­rect­ed Walk­ing

For me the big­gest thrill of this project was im­ple­ment­ing some form of redi­rect­ed walk­ing. We want­ed the us­er to walk through a wall, since the theme of the es­cape room was to avert the users ex­pec­ta­tions he brought with him from re­al­i­ty.

But at the same time our mod­el of the room matched the re­al room 1:1 in scale. And in vir­tu­al re­al­i­ty scale is su­per im­por­tant, so we couldn’t sim­ply scale down the room.

In­stead we sped up the users move­ment in one di­rec­tion and slowed him down in the oth­er, re­sult­ing in a mis­match be­tween the re­al and vir­tu­al world. This worked re­al­ly well, be­cause we po­si­tioned keys and puz­zles in a way that the us­er had to cross the en­tire room mul­ti­ple times al­low­ing us to use the full width of the room while know­ing where the us­er would go next.

By mov­ing the track­ing ori­gin ac­cord­ing to the users rel­a­tive move­ment, we were able to cre­ate a mis­match of around 2 me­ters on a rough­ly 5 me­ter long room with the us­er walk­ing three lengths.

From left to right: vir­tu­al (in blue) and re­al room com­bined, re­al room on­ly, vir­tu­al room on­ly. The green area is the HTC Vive track­ing area.

If you know you are be­ing redi­rect­ed you no­tice of course. Kin­da like with im­mer­sion in VR: you can’t fool your sub­con­scious un­less you are oth­er­wise en­ganged, since you are con­stant­ly think­ing “I know I’m in VR”. When en­ganged (e.g. by hold­ing a key with­out ac­ci­den­tal­ly mov­ing their hands out­side of the Leap Mo­tion’s field of view), peo­ple would not re­al­ize what was hap­pen­ing.

The fi­nal ef­fect was abo­lute­ly mind blow­ing. Peo­ple be­liev­ing they would be un­able to walk through the wall and then over­com­ing this be­lief is one of the most in­cred­i­ble things I wit­nessed in quite a while.

Per­son­al­ly I com­pare cre­at­ing il­lu­sions like this in VR to mag­ic, since it has a sim­i­lar­ly mind blow­ing ef­fect and it is a lot about hid­ing what you are ac­tu­al­ly do­ing from the play­ers at­ten­tion by keep­ing him dis­tract­ed oth­er­wise.

This fea­ture was a team ef­fort: Daniel, Rox­anne and I had a lot of fun im­ple­ment­ing this to­geth­er on site and ex­per­i­ment­ing how far you could go with­out get­ting sick and mak­ing it just bare­ly not­i­ca­ble.

Mo­tion Sick­ness

Sim­u­la­tion or mo­tion sick­ness is one of vir­tu­al re­al­i­ty’s big­gest prob­lems. Once you have a mis­match be­tween vis­ual and vestibu­lar 1 in­put, your brain goes “oh my god, I might have eat­en a poi­sonous mush­room and must be hal­lu­ci­nat­ing” re­sult­ing in your stom­ach be­ing very un­hap­py with the sit­u­a­tion.

We are in­deed cre­at­ing a vis­ual/vestibu­lar mis­match here, but if you don’t over­do the ef­fect, it ac­tu­al­ly works with­out mo­tion sick­ness. Why is that?

An ef­fect that we’re al­so ex­ploit­ing in an unan­nounced game at Vhite Rab­bit is that if your brain re­ceives in­put about ac­cel­er­at­ing in one di­rec­tion, it’s not ac­tu­al­ly picky about how much ac­cel­er­a­tion it sees, as long as the di­rec­tion match­es that vestibu­lar in­put. You can lit­ter­al­ly speed up the play­er by a huge fac­tor in the same di­rec­tion with­out him get­ting sick.

Up Next

To­mor­row we’ll have a look at some ren­der­ing de­tails for Uni­ty, but al­so some gen­er­al con­cept that may be in­ter­est­ing to non-Uni­ty users.

The sys­tem in your in­ner ear that keeps track of ori­en­ta­tion and ac­cel­er­a­tion.

Writ­ten in 60 min­utes, ed­it­ed in 15 min­utes.