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Absolute vs. Relative Pointing

Movea and Hillcrest Labs in Agreement?

This was going to be a story exposing a simmering feud, an ongoing debate, a religious war. As it turns out, it feels more like violent agreement than anything else.

I’m not here to point fingers at anyone. I am here, however, to discuss pointing. I’ll bet you didn’t know there was a technical debate about that, now, did you? Let’s talk first about what we’re talking about, and then I’ll return to the controversial (?) bits.

Pointing is, of course, natural. Even dogs can figure out when we’re pointing at something. (Some dogs, anyway… others prefer to keep looking at your finger…) And so we’ve worked it into our technology, ever since Apple Xerox came up with the concept of the mouse.

As Hillcrest Labs CEO Dan Simpkins notes, we have to do some mental translation when we use a mouse: we have to rotate our frames of reference by 90°. So when we want the cursor on our screen to go up, we don’t move our mouse up; we move it forwards. But this seems to work pretty well and doesn’t seem to take much, if any, getting used to. Heck, most of us had to learn to do that when drawing in school: the flat paper on the desk is rotated from the world we’re looking at (at least until the point when we can afford an easel).

But things have changed: computers are no longer our only interactive technology device. Televisions, which used to be passive, are now acting much as our computers, but with a different set of input devices. In fact, we’re normally limited to the remote control.

Now… there are enough buttons on a remote control to where we could practically use it as a full keyboard, except that most of us have no idea how to use any of those buttons. We’d probably try to type something and get locked into some weird TV setup mode that would reprogram all the channels for Klingon TV or something. So that’s not a promising approach.

The left/right/up/down buttons have helped us to navigate the old-school TV directory stuff. (It kills me that online TV directories are considered old-fashioned… why in my day…) But what we can attempt these days goes way beyond an endless procession of direction-button pushes. And this is where using the remote as a pointer comes in.

The idea is that you point at the TV, and motion sensors in your remote keep track of what you’re doing and move the cursor (or your annoyed avian or your Howitzer or whatever) in response to how you move the remote. Seems pretty obvious, right?

Well, it’s actually not. And here’s where we get into the stuff that matters. Because this is supposedly a debate about what’s easiest and most natural for a user when it comes to pointing. And, at first glance, that would seem to be the following: point directly at what you want to point at. Duh, right? I mean, if your affable golden retriever briefly took his eyes off the ball because he thought he saw the shadow of a leaf falling that might have been caused by a SQUIRREL, then you get him back on track by pointing at the ball, right? You don’t point at some abstract place on a wall and hope the dog can visualize a frame translation. No, you point at the ball.

What could possibly be complicated about that?

Well, OK; let’s do some gedanken work here. You walk into your living room and point at the TV to turn it on and set the channel. You arrange the cushions and throws on the couch (OK, if you’re a bachelor, then you push the empty beer cans out of the way onto the floor where they belong) and lay back, kind of on your side, to watch the soothing scenes from the latest brain-dead-reality-show-spun-off-from-some-prior-brain-dead-reality-show.

And then you decide that this one is too brain dead and want to scan around for something that might have one or two errant neurons still firing. If you’re lying on your right side and you’re right-handed, then you sort of have to awkwardly bring that buried arm (equivalent to your numbed lower spooning arm) out and point it at the TV to change the channel.

OK, granted, as world crises go, this doesn’t rank very high. Definite first-world problem. But, having acknowledged that, this is an uncomfortable way to point.

And therein lies a critical nuance: it’s very natural to point this way, but it’s, well, awkward. It would be so much easier just to point someplace on the opposite wall without having to wrench any joints into unnatural angles. (Can you imagine that early man actually GOT UP AND WALKED TO THE TV to change channels?? Talk about awkward and unnatural!!)

So this example brings out the two ways of pointing. The first one is like using a laser pointer: you point exactly at what you want. And that’s absolute pointing because there is an absolute frame of reference. If you point at the TV, the cursor will appear where you point. If you point at the wall, then perhaps the cursor will disappear or get pinned to the side of the TV screen. But it would be on the wall if it could get there.

The alternative is called relative pointing. It allows any arbitrary re-centering. You can move the origin anywhere and the system won’t care. If you point at the wall and establish a new frame of reference, then the TV cursor will happily respond to your movements. If it were that golden retriever, then you’d point at the wall and it would go, “Ah, it’s under the couch!” and everyone would be happy.

We’ve seen where absolute pointing can be uncomfortable; should it simply be replaced with relative pointing? Ah… now we’re getting into debate territory. And we’re not quite ready for that yet. Because there’s a detail that I’ve glided over that some of you may have noticed. I talked about changing the frame of reference, but how exactly do you do that?

The answer to that question depends on the system. On old systems, there was a cursor on/off button, and turning the cursor on always brought it up in the middle of the screen, so if all else failed, you could turn it off and on again. According to Mr. Simpkins, you can re-center some LG systems by vigorously shaking the remote. That shake effectively becomes a gesture whose meaning is to re-establish the frame of reference.

With others, the cursor pegs once you hit the side of the screen. Within the screen, you’re moving in a fixed frame; once you leave the screen, the cursor stops moving at the edge and you’re dragging the frame around. So by moving the remote to point to the wall – let’s say it’s to the left of the TV, the system is reorienting its coordinates. Once you stop and move to the right again, the cursor will now behave as if you were pointing at the screen – until you go so far to the right that you go off-screen on the right side, at which point the frame gets dragged back to the right again.

And this is where the debate, such as it is, lives. Hillcrest Labs, as a matter of policy and almost of religion (except that they have some actual facts and evidence to back up their position), believes strongly (“strongly” may not be strong enough) in the value of relative pointing because, in the end, it’s more comfortable. It does take a slight bit of training for a novice to get used to the re-centering concept, but that happens fast.

But I came to this topic via an announcement from Movea saying that they had released an absolute pointing system. When I contacted them, it was simply to learn more about what this meant. But I came away with the distinct sense that there were differing views, which is why I dug in more.

I should pause for anyone here that isn’t familiar with these two companies. Both Hillcrest Labs and Movea are sensor-agnostic sensor fusion companies (i.e., they don’t make their own sensors and their algorithms aren’t tied to any specific brand of sensor), and much of their business seems to be in remote controls. So they’re both deeply embedded in this space. They’re not the only sensor fusion guys around, but they somehow seem like natural competitors in the way that Altera and Xilinx are.

Given that Hillcrest likes relative and Movea just announced absolute, you might think that they’re on opposite sides of this debate. But Movea agrees that, for casual TV watching and such, a relative pointing system is preferable. So there’s no apparent disagreement here.

Where things get a bit (but only a bit) more heated is when it comes to gaming. For intense gaming, the re-centering thing can be distracting. Let’s say you cock your shotgun in a first-person-shooter game. You do that by flexing your wrist up and back. But for a second there, you pointed out of frame, so the frame got moved slightly: you need to re-center.

Or let’s say you use your remote* hand to wipe the sweat from your brow (the other hand having the higher-priority task of holding your beer); then, for a second, your remote is pointing… who knows where. So the first thing you need to do once that hard-earned perspiration has been dabbed is to re-center. In a fight to the death, such delays and distractions can kill.

But even here, there’s not much disagreement. Movea thinks that absolute can provide a better intense gaming experience (no lolling back on the couch here!); Hillcrest agrees that it’s conceivable that it might. The only practical difference is that Movea has released a product that uses absolute pointing; Hillcrest says that they have the technology internally, but haven’t yet had a product or collaboration that required it.

So… so much for a big dust-up. Nothing to see here, folks… move along.

There is a little more nuance to Movea’s position. They divide gaming into the casual gamer, who might play a game for a short time (10 minutes or so) and then go do something else, and the serious gamer, who will play for long periods with great intensity.

For the casual guy, you can establish an absolute frame, but Movea’s Dave Rothenberg used the term “quasi-absolute.” That’s because, in those setups, the remotes have only an accelerometer and a gyroscope, so frame drift can be an issue over time. That’s why the short gaming interval is key – it’s not enough time for drift to become a problem.

For the serious dudes and dudettes, you need to add a magnetometer to the deal to help stabilize that permanent absolute frame.

Why not just add a magnetometer in all remotes? One word: cost. Apparently remotes operate on razor-thin margins, so every nanopenny counts. Putting a magnetometer in a garden-variety remote is going to be a hard sell; those remotes almost always have six axes. It’s only in the higher-level purpose-built devices that a magnetometer can be included.

Now… having somewhat dispensed with this absolute-vs.-relative debate, there is yet more nuance that might fuel a future duel. Let’s do a little demonstration here. Point your remote at your computer. (It’s OK if you need to go get it; I can wait.) Now, keep pointing in the same direction, but rotate your wrist around so that you’ve turned the remote upside down, but still pointing at the screen.

According to the remote, which direction is up? In most cases, “up” is defined by the top of the remote, so if you rotate your wrist like that, up becomes down and vice versa. Hillcrest claims the unique position of being able to correct for that rotation so that “up is always up” no matter which way the remote is oriented. And they have a patent on it.

There are also “ballistics” details – how fast does the cursor move? With relative pointing, non-linear ballistics are often used, meaning that if you move your hand faster, the cursor moves faster and farther – and by more than the amount by which you sped up your hand motion. With absolute pointing, which implies a closer link between your hand movements and the screen action, you might stick with linear ballistics.

But if those details are going to spark a debate, we’ll have to come back to that another time.

So… let’s summarize. Absolute pointing means absolute frame of reference; it’s like using a laser pointer. Where you point is where you point. Relative pointing means the frame can move to a more comfortable place. Where you point establishes where your frame is. You may need to re-center.

Relative is most comfortable for most applications; serious gamers can benefit from absolute pointing. The only real distinction between Movea and Hillcrest Labs on this score is whether they’ve productized their absolute technology. Movea has; Hillcrest hasn’t. They both seem happy with their decisions.

I know; not much of a fight. Sorry about that. I’ll try to dig up something bloodier next time.



*I use the word “remote” loosely here. It may be a simple TV remote, or it may be a more complex gaming thing. But they both act like remotes.

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