Friday Takeaway: Why Your iPad Can't Do 3D (Yet)

Most of you have probably watched a 3D movie. Perhaps it was an old movie with those iconic blue and red tinted glasses. Maybe you caught an IMAX documentary in 3D. Or maybe you watched a blockbuster like Avatar or Toy Story 3 in 3D. Chances are, you probably took a few pairs of glasses home with you in the hopes that you could have the same experience on your sofa. Unfortunately for you, that's not going to happen. And just so you know, they won't work with your iPad, either.

It's sad news, indeed. I was even holding on to a pair of Real3D glasses from the theater, just in case I'd be able to use them with some fancy new 3DTV down the line. As it turns out, though, the technology used in the theater is not even close to what is being used in the home, and even that technology is not going to work with the iPad. Here's why.

For starters, I think we can all agree that the old red and blue tinted (anaglyph) glasses are terrible. While it does provide the 3D effect, it produces tons of ghosting and more or less doesn't work if you're not viewing at the correct angle.

Modern theaters primarily use a method called circular polarization. Here, two projectors are used; each projector has a filter over each eye that polarizes the light in a circular fashion. The cheap glasses you wear have lenses that polarize the light differently in each eye so that you only see the light coming from one projector in each eye. The result creates a stereo image that induces the 3D effect.

The reason you don't see this technology in the consumer market is twofold. First, while there are smaller sets that duplicate this type of projection, they require two projectors; thus, regardless of how good your TV is, you'd be forced to buy a new one (more TV purchases in a minute). Second, to create a true 1080p image on such a set would require the screen to actually display a resolution of 1920x2160 (as opposed to the normal 1920x1080). If the resolution was only 1920x1080, each eye would only be seeing an image that is 1920x560, and thus not true HD. You can imagine the extra cost in creating a TV with such a high resolution, not to mention the fact that there is an inherent aliasing problem (jagged edges) created by this technology that is vastly more apparent on TV screens, which are much, much smaller than your average theater screen.

It's fairly obvious that this is not the type of technology used in the iPad.

Now, despite what the TV manufacturers want you to believe, you don't necessarily need to go out and buy a new TV just to have 3D capabilities. This is all you really need for 3D: a TV set with a refresh rate of at least 120 Hz, a pair of those expensive ($150) glasses, and a sensor to sync up with your glasses. You see, while those glasses you wear at the theater may only cost a few dollars to make, the glasses for use with TVs are actually electronic devices.

In a nutshell, the TV is refreshing at a rate of (optimally) 240 Hz. The sensor (either built into the TV or set top box or an external attachment) then syncs up with your glasses (which are actually small LCD screens), alternately blocking and allowing light into each eye. This occurs at a rate of up to 5 times per eye for each frame (10 times total x 24 frames per second). With a TV that has a refresh rate of 240 Hz, everything syncs together and you get the resulting illusion of three dimensions.

When I said that you don't necessarily need to get a new TV to view 3D, this is because this all is possible with a TV that has a true refresh rate of 120 Hz (not all TVs claiming 120 Hz are actually displaying at 120 Hz). According to what we know, a 3D Blu-Ray player such as the PS3 will display 3D at 120 Hz, so if you purchase a sensor and its corresponding glasses, you could watch movies and play games in 3D. Will the result be as fluid as a 240 Hz TV? No; there may be some ghosting, but it's definitely cheaper than buying a brand new TV for upwards of $2,000.

So what does this all have to do with the iPad? As with most computer monitors, the iPad only has a refresh rate of 60 Hz. This means that the screen simply isn't refreshing fast enough to allow a 3D effect to take place. Regardless of whether you own a pair of the expensive LCD glasses or a cheap pair you took from the local cinema, they will be of no use to you on the iPad.

With the Nintendo 3DS coming most likely next year, the iPad could be facing some serious new competition in the mobile gaming market. After all, the 3DS allows for 3D visuals without needing glasses at all. Can the iPad possibly compete?

As a matter of fact, yes it could, but not in its current form. A little app called HoloToy paved the way. While HoloToy doesn't provide 3D in the exact same way (it pops out at you as much), it does provide a three-dimensional effect in that it looks as if you are looking through a window; move your device around, and the level of depth changes. If you haven't checked out the app, it's worth a look.

Now, here is the interesting part. Mind you, this is all theoretical. The iPad lacks many of the sensors that the iPhone has. It has an ambient light sensor and accelerometer, but that's about it. The iPhone 4, on the other hand, also has a gyroscope, a proximity sensor, and a front-facing camera. This is why these three are important.

1. The gyroscope is important because of how much easier it can detect your movement. Think of how Steve Jobs spun around in his demo of the block game at WWDC, and the screen reacted accordingly. With full six-axis motion, movement is recorded incredibly precisely. Think of how this could improve something like HoloToy

2. The proximity sensor is a bit of a mystery. In my research, I was not able to come up with a definitive answer as to exactly how it works, although the general consensus is that it is infrared. Using it, to some degree, the iPhone knows how far away you are from the device.

3. The front-facing camera can see you. Well, it can see the light bouncing off of you. With software, this can be used to determine your position in relation to the iPhone. Think of how Microsoft's Kinect detects you and your movements.

The reason to bring all of these up is Johnny Chung Lee's head-tracking demo using the Wii remote.

As you can see in the video (the visual demonstration hits after the 3-minute mark), if the software can tell how far away you are from the screen, it's possible to alter the images according to your head movement, simulating a surprisingly realistic 3D effect. Is this possible with the iPad? More than likely, with some good old fashioned ingenuity, yes.

Of course, for it to be possible, Apple needs to refresh the iPad with all of the things we expect them to do anyway (those additional sensors). The rest is software, and if Apple takes the initiative to create APIs for developers to work with, it could become a platform standard.

Of course, if none of this actually works, you can still put on the old red and blue glasses for a spectacularly underwhelming (but still 3D) effect. We've got our fingers crossed for the former.

Many thanks to Kevin George for providing additional research for this article.