Difference Between VR and AR

This weekend, my sister Sarah challenged me to define the difference between Virtual Reality and Augmented Reality. And the more I talked about the differences between them, the more I realised that I don’t have a concrete definition, and I don’t think that anybody else does either.

A man wearing a VR headset while writing on a whiteboard.
AR: the man sees simulated reality and, probably, the whiteboard.
VR: the man sees simulated reality only, which may or may not include a whiteboard.
Either way: what the hell is he doing?

After all: from a technical perspective, any fully-immersive AR system – for example a hypothetical future version of the Microsoft Hololens that solves the current edition’s FOV problems – exists in a theoretical superset of any current-generation VR system. That AR augments the reality you can genuinely see, rather than replacing it entirely, becomes irrelevant if that AR system could superimpose a virtual environment covering your entire view. So the argument that compared to VR, AR only covers part of your vision is not a reliable definition of the difference.

Spectrum showing AR view of the Louvre on the left (with 5% of the view occluded by UI) and VR view of a 3D model of the Louvre on the right (with 100% of the view occluded). The middle of the spectrum remains undefined.
The difference by how much of your view is occluded by machine-generated images fails to define where the boundary between AR and VR lies. 5%? 50%? 99%?

This isn’t a new conundrum. Way back in 1994 back when the Sega VR-1 was our idea of cutting edge, Milgram et al. developed a series of metaphorical spectra to describe the relationship between different kinds of “mixed reality” systems. The core difference, they argue, is whether or not the computer-generated content represents a “world” in itself (VR) is just an “overlay” (AR).

But that’s unsatisfying for the same reason as above. The HTC Vive headset can be configured to use its front-facing camera(s) to fade seamlessly from the game world to the real world as the player gets close to the boundaries of their play space. This is a safety feature, but it doesn’t have to be: there’s no reason that a HTC Vive couldn’t be adapted to function as what Milgram would describe as a “class 4” device, which is functionally the same as a headset-mounted AR device. So what’s the difference?

You might argue that the difference between AR and VR is content-based: that is, it’s the thing that you’re expected to focus on that dictates which is which. If you’re expected to look at the “real world”, it’s an augmentation, and if not then it’s a virtualisation. But that approach fails to describe Google’s tech demo of putting artefacts in your living room via augmented reality (which I’ve written about before), because your focus is expected to be on the artefact rather than the “real world” around it. The real world only exists to help with the interpretation of scale: it’s not what the experience is about and your countertop is as valid a real world target as the Louvre: Google doesn’t care.

Milgram et al. (1994)'s Table 1: Some major differences between classes of Mixed Reality (MR) displays, showing seven classes: 1. monitor-based video with CG overlays, 2. headset-based video with CG overlays, 3. headset-based see-through display with CG overlays, 4. headset-based see-through video with CG overlays, 5. monitor/CG world with video overlays, 6. headset-based CG world with video overlays, and 7. CG-based world with real object intervention.
Categories 3 and 4 would probably be used to describe most contemporary AR; categories 6 and 7 to describe contemporary VR.

Many researchers echo Milgram’s idea that what turns AR into VR is when the computer-generated content completely covers your vision.

But even if we accept this explanation, the definition gets muddied by the wider field of “extended reality” (XR). Originally an umbrella term to cover both AR and VR (and “MR“, if you believe that’s a separate and independent thing), XR gets used to describe interactive experiences that cover other senses, too. If I play a VR game with real-world “props” that I can pick up and move around, but that appear differently in my vision, am I not “augmenting” reality? Is my experience, therefore, more or less “VR” than if the interactive objects exist only on my screen? What about if – as in a recent VR escape room I attended – the experience is enhanced by fans to simulate the movement of air around you? What about smell? (You know already that somebody’s working on bridging virtual reality with Smell-O-Vision.)

Dan and Robin concluding a VR Escape Room.
Not sure if you’re real or if you’re dreaming? Don’t ask an XR researcher; they don’t know either.

Increasingly, then, I’m beginning to feel that XR itself is a spectrum, and a pretty woolly one. Just as it’s hard to specify in a concrete way where the boundary exists between being asleep and being awake, it’s hard to mark where “our” reality gives way to the virtual and vice-versa.

It’s based upon the addition of information to our senses, by a computer, and there can be more (as in fully-immersive VR) or less (as in the subtle application of AR) of it… but the edges are very fuzzy. I guess that the spectrum of the visual experience of XR might look a little like this:

Comic showing different levels of "XR-ness", from the most to the least: The Matrix has you now, fully immersive VR, headset AR, "Magic Window" AR, conventional videogaming, HUDs, using google maps while walking, imagining playing Tetris, reality.

Honestly, I don’t know any more. But I don’t think my sister does either.

Subscribing to The Far Side (by RSS!)

Prior to his retirement in 1995 I managed to amass a collection of almost all of Gary Larson’s The Far Side books as well as a couple of calendars and other thingamabobs. After 24 years of silence I didn’t expect to hear anything more from him and so I was as surprised as most of the Internet was when he re-emerged last year with a brand new on his first ever website. Woah.

The Far Side by Gary Larson

Larson’s hinted that there might be new and original content there someday, but for the time being I’m just loving that I can read The Far Side comments (legitimately) via the Web for the first time! The site’s currently publishing a “Daily Dose” of classic strips, which is awesome. But… I don’t want to have to go to a website to get comics every day. Nor do I want to have to remember which days I’ve caught-up with, yet. That’s a job for computers, right? And it’s a solved problem: RSS (which has been around for almost as long as Larson hasn’t) and similar technologies allow a website to publicise that it’s got updates available in a way that people can “subscribe” to, so I should just use that, right?

Except… the new The Far Side website doesn’t have an RSS feed. Boo! Luckily, I’m not above automating the creation of feeds for websites that I wish had them, even (or perhaps especially) where that involves a little reverse-engineering of online comics. So with a little thanks to my RSS middleware RSSey… I can now read daily The Far Side comics in the way that’s most-convenient to me: right alongside my other subscriptions in my feed reader.

The Far Side comics in Dan's RSS reader.
How screen scrapers are made.

I’m afraid I’m not going to publicly*-share a ready-to-go feed URL for this one, unlike my BBC News Without The Sport feed, because a necessary side-effect of the way it works is that the ads are removed. And if I were to republish a feed containing The Far Side website cartoons but with the ads stripped I’d be guilty of, like, all the ethical and legal faults that Larson was trying to mitigate by putting his new website up in the first place! I love The Far Side and I certainly don’t want to violate its copyright!

But – at least until Larson’s web developer puts up a proper feed (with or without ads) – for those of us who like our comics delivered fresh to us every morning, here’s the source code (as an RSSey feed definition) you could use to run your own personal-use-only “give me The Far Side Daily Dose as an RSS feed” middleware.

Thanks for deciding to join us on the Internet, Gary. I hear it’s going to be a big thing, someday!

* Friends are welcome to contact me off-blog for an address if they like, if they promise to be nice and ethical about it.

It’s 2020 and you’re in the future

This article is a repost promoting content originally published elsewhere. See more things Dan's reposted.

West Germany’s 1974 World Cup victory happened closer to the first World Cup in 1930 than to today.

The Wonder Years aired from 1988 and 1993 and depicted the years between 1968 and 1973. When I watched the show, it felt like it was set in a time long ago. If a new Wonder Years premiered today, it would cover the years between 2000 and 2005.

Also, remember when Jurassic Park, The Lion King, and Forrest Gump came out in theaters? Closer to the moon landing than today.

These things come around now and again, but I’m not sure of the universal validity of observing that a memorable event is now closer to another memorable event than it is to the present day. I don’t think that the relevance of events is as linear as that. Instead, perhaps, it looks something like this:

Graph showing that recent events matter a lot, but rapidly tail off for a while before levelling out again as they become long-ago events.
Recent events matter more than ancient events to the popular consciousness, all other things being equal, but relative to one another the ancient ones are less-relevant and there’s a steep drop-off somewhere between the two.

Where the drop-off in relevance occurs is hard to pinpoint and it probably varies a lot by the type of event that’s being remembered: nobody seems to care about what damn terrible thing Trump did last month or the month before when there’s some new terrible thing he did just this morning, for example (I haven’t looked at the news yet this morning, but honestly whenever you read this post he’ll probably have done something awful).

Nonetheless, this post on Wait But Why was a fun distraction, even if it’s been done before. Maybe the last time it happened was so long ago it’s irrelevant now?

XKCD 1393: Timeghost - 'Hello, Ghostbusters?' 'ooOOoooo people born years after that movie came out are having a second chiiiild right now ooOoooOoo'
Of course, there’s a relevant XKCD. And it was published closer to the theatrical releases of Cloudy with a Chance of Meatballs and Paranormal Activity than it was to today. OoooOOoooOOoh.

Forward #100 – Gamification

This article is a repost promoting content originally published elsewhere. See more things Dan's reposted.

Forward Comic issue 100, frame 1

(It should be noted that I have now made 100 Forward strips. I’m not saying that I’ve earned myself a blowjob, but I’m also not not saying that.)

Sure: I think you’ve earned a blowjob, Tailsteak. I think we might need a spin-off of Patreon where you can offer content creators sexual favours in exchange for their work…

(In other news, I’ve said before that you should read Forward, and now’s a great time to start. You can catch up, don’t worry.)

LABS Comic RSS Archive

Yesterday I recommended that you go read Aaron Uglum‘s webcomic LABS which had just completed its final strip. I’m a big fan of “completed” webcomics – they feel binge-able in the same way as a complete Netflix series does! – but Spencer quickly pointed out that it’s annoying for we enlightened modern RSS users who hook RSS up to everything to have to binge completed comics in a different way to reading ongoing ones: what he wanted was an RSS feed covering the entire history of LABS.

LABS comic adapted to show The Robot literally "feeding" RSS
With apologies to Aaron Uglum who I hope won’t mind me adapting his comic in this way.

So naturally (after the intense heatwave woke me early this morning anyway) I made one: complete RSS feed of LABS. And, of course, I open-sourced the code I used to generate it so that others can jumpstart their projects to make static RSS feeds from completed webcomics, too.

Even if you’re not going to read it via this medium, you should go read LABS.

Escape Room [NSFW]

This article is a repost promoting content originally published elsewhere. See more things Dan's reposted.

Frame from Tailsteak's 20-page comic "Escape Room"

Regular readers will know already that I’ve been a huge fan of comic author Tailsteak, ever since Ruth, many years ago, introduced me to his work. I’m particularly enjoying Forward, his latest webcomic: so much so that in an effort to work around its lack of an RSS feed I accidentally stole unpublished work from him earlier this year (oops!).

He announced yesterday his new secondary Twitter account, @TailsteakAD (the “AD” is for “After Dark”) and was delighted from the very top tweet onwards:

TailsteakAD: For the record, just because an artist makes erotic work, or even has a dedicated adult-themed account, that in no way implies that they have any desire whatsoever to receive your unsolicited sexual messages or images. I mean, *I* want'em, but other artists might not.
That’s the spirit.

Anyway: a short while later I found a 20-page comic he’d made called The Escape Room: read it on Twitter or via Threadreader. It might be exactly the comic you’ve always been looking for, assuming that the comic you’ve always been looking for combines B/D, gay sex, and escape room puzzle mechanics. NSFW, obviously.

Suddenly I feel like the escape rooms I go to aren’t quite as good as I thought.