Daniel Hruska When it's released in the fall iOS 7, we will get a bunch of new features in our apple devices. In addition to a completely redesigned, sometimes even controversial, appearance, Apple offers us a completely new paradigm of user enjoyment. It seems that Apple wants to prepare its mobile system for the next decade with this drastic step.
Among the novelties is the so-called parallax effect. If I should quote Wikipedia, parallax (from Greek παράλλαξις (parallaxis) meaning "change") is the angle subtended by straight lines drawn from two different locations in space to the observed point. Parallax is also referred to as the apparent difference in the position of a point relative to the background when viewed from two different locations. The further the observed object is from the observation points, the smaller the parallax. Most of you probably get goosebumps at the memory of school desks and boring physics classes.
In practice, this simply means that with a bit of clever programming, the display turns into something more. Suddenly, it is not just a two-dimensional surface with matrices of icons and other elements of the user environment, but a glass panel through which the user is able to see the three-dimensional world while filming the device.
Perspective and parallax
The basic principle of how to create a functional parallax effect on a two-dimensional display is quite simple. Because light passes through the eye to a single point, the brain had to learn to recognize the size of objects relative to the angle between their edges. The result is that closer objects appear large, while distant objects appear small.
These are the basics of perspective perception, which I'm sure each of you has heard of at some point. Parallax, in this iOS context, is the apparent movement between these objects as you move around them. For example, when you are driving a car, closer objects (trees by the roadside) move faster than more distant ones (hills in the distance), even though they are all standing still. Everything changes its places differently at the same speed.
Along with several other tricks of physics, perspective and parallax play a very important role in our perception of the world around us, enabling us to sort and understand the various visual sensations that our eyes capture. In addition, photographers with a sense of perspective they like to play.
From rockets to phones
In iOS, the parallax effect is completely simulated by the operating system itself, with a little help from technology originally developed for launch vehicles. Inside the latest iOS devices are vibrating gyroscopes, devices smaller than a human hair that oscillate at a given frequency when exposed to an electrical charge.
As soon as you start moving the device along any of the three axes, the whole mechanism starts to resist the change in orientation due to Newton's first law, or the law of inertia. This phenomenon allows the hardware to measure the speed and direction the device is being rotated.
Add to this an accelerometer that can detect the orientation of the device, and we get an ideal interplay of sensors to very precisely detect the necessary data to create the parallax effect. Using them, iOS can easily calculate the relative movement of individual layers of the user environment.
Parallax for everyone
The problem of parallax and the illusion of depth can be solved in a straightforward way thanks to mathematics. The only thing the software needs to know is to organize the content into a set of planes and then move them depending on their perceived distance from the eyes. The result will be a realistic rendering of depth.
If you've been watching WWDC 2013 or iOS 7 introductory video, the parallax effect was clearly shown on the main icon screen. When moving the iPhone, they seem to float above the background, which creates an artificial impression of space. Another example is the subtle movement of open tabs in Safari.
However, the exact details are shrouded in mystery for now. Only one thing is clear - Apple intends to weave parallax across the entire system. This may, after all, be the reason why iOS 7 will not be supported on the iPhone 3GS and the first-generation iPad, since neither device has a gyroscope. It can be expected that Apple will release an API for third-party developers to also benefit from the third dimension, all without much power consumption.
Genius or tinsel?
While most of iOS 7's visual effects can be comprehensively described vicariously, parallax requires its own experience. You can watch dozens of videos, whether official or otherwise, but definitely do not evaluate the parallax effect without trying it yourself. Otherwise, you will have the impression that this is only an "eye" effect.
But once you get your hands on an iOS 7 device, you'll see another dimension behind the display. This is something that is very difficult to describe in words. The display is no longer just a canvas on which applications displaying imitations of real materials are rendered. These are replaced by visual effects that will be synthetic and realistic at the same time.
More than likely, once developers start using the parallax effect, apps will be overwhelmed with it as everyone tries to find the right way to use it. However, the situation will stabilize before long, just like with previous iOS versions. However, at the same time, completely new applications will see the light of day, the possibilities of which we can only dream about today.
the question is, if they release the API for 3rd party developers, it won't be used quickly by the competition…. ?! That would be a shame! :(
Paralax live wallpaper was released for android a few days after the introduction of ios7. Control center after about a week I suspect.
Paralax Live wallpaper was released a long time before iOS 7 :-) When I had an LG Optimus 3D, I was sorry that it only used 3D in certain things, so I put a live wallpaper that simulated a 3D effect :-) Under the Parallax Barrier, it also hides the technology that LG Optimus 3D and HTC EVO 3D had and now even a few new TVs. The original manufacturer of this technology for 3D without glasses was BMW in on-board computers so that the driver could watch navigation and the passenger a movie. Otherwise, in iOS 7, this effect appears quite often – on the desktop, in Safari, on the locked desktop when using panoramic photos, and also when the volume is reduced. It just annoys me that they delete relatively cool features in individual betas. The transparent keyboard in messages is gone, the transparent notification bar is gone….
The API for third-party developers doesn't have much effect on this. Competing systems can't use this API, so the only thing left to do is reverse engineer it anyway. And that doesn't make much sense with such a well-documented* effect.
*now I don't think you'll find the exact code from iOS anywhere, but parallax, like perspective, is a fairly well-known and researched phenomenon.
As a developer bound by NDA, I can't say that iOS 7 includes the Motion Effects API. And I can't say that I used it immediately after the release of the first beta and that it's great.
:D
In any case, the developers always had access to the accelerometer and gyroscope, that's why it's there. The advantage here is that Apple ... ahem ... can simply connect the effects to each UIView, which can have any parameter (size, position, etc.) variable based on the rotation and movement of the device.
The full API for these effects has been released a long time ago... That's what I would say if I could talk about it :)
I remember that in some iOS6 beta, the volume slider changed reflections depending on the tilt of the device, and there was nothing in the sharp version.
I've had iOS 7 beta for a few months now, but if I remember correctly, this effect is normally present in iOS 6.1 sharp version. But I might be wrong, I really can't verify it anywhere, I have iOS 7 everywhere.
Sorry to write a whole article about a moving background - seeing as it's cucumber season.
It's more obvious that you don't know what it's about, that it's not just an ordinary moving background.
Nice article full of specific information.
Great article. I've been waiting for something about parallax for a long time when Apple used it. It can have a lot of new possibilities.
Nice article
It already looks beautiful from the video and I can't imagine how amazing it will be when I have it on my iPhone. Splendor!
The fact is that Android has had it for a long time, in the form of an application, and it doesn't bother anyone much.
It won't work on iPhone 4…
I'm afraid what the flashlight will say about it, this is a nice portion of extra calculations.
What can be boring in physics class?
After all, physics is one of the most interesting sciences!!!
The article is very interesting, but some things are not accurately explained. First of all, parallax is rather the angle between the line segments connecting two different points of observation and the object, which is always less than the straight angle (Wiki is rather imprecise on this - it is difficult to specify what the angle is for the angle of two straight lines). And then to Newton's law: if we start moving the phone, we give it an acceleration. However, the law of inertia does not discuss acceleration at all. The principle on which this function is based rather comes from the properties of non-inertial frames of reference, which Newton also dealt with, but not as part of his first law of motion.
“And then to Newton's law: if we start moving the phone, we give it an acceleration. However, the law of inertia does not discuss acceleration at all."
I don't understand how this argument proves that it is not a law of inertia.
As far as I remember, the gyroscope works on the principle of changing the moment of momentum, which generates force. And that depends on the moment of inertia. So, in my opinion, it is both the law of inertia and the law of force for a rotating system.
Don't confuse the accelerometer with the gyroscope. The accelerometer records the acceleration of the object due to inertia. The gyroscope is a flywheel located in a three-axis rotor, due to which this flywheel does not change its position relative to the ground during any rotation of the entire device.
Bottom line – the accelerometer perceives movement, while the gyroscope perceives position (rotation). ;)
Thanks for the heads up, but I really don't confuse the two. Parallax has nothing to do with the accelerometer, it controls the gyroscope.
The gyroscope you describe is actually not in the iPhone. There is a mechanical grid that deforms with rotation, so nothing there rotates by itself (that's how a classic gyroscope works, e.g. described on Wikipedia).
However, this deformation is really caused by rotational inertia, so... somehow I don't understand where you got the idea that you are confusing the accelerometer with the gyroscope (there was no mention of the accelerometer at all).
I'm not suggesting that parallax has anything to do with accelerometer ;). The gyroscope does not work on the principle of momentum change - that would mean that it only reacts to acceleration (p=m*v). A change in momentum would therefore (assuming constant mass) mean a change in speed - acceleration. However, the gyroscope also reacts to a change in position during uniform rectilinear movement. However, inertia is applied to the body of the flywheel (whether it is represented by a classic heavy wheel or a grid).
Otherwise, of course, I agree with you that Martin Hájek's statement about the first law of motion is somehow toothless. Although the magnitude of the acceleration does not appear directly in this law, it essentially answers the question: why is the acceleration detectable even within the inertial frame of reference...
In conclusion, I would like to note that physics is beautiful and I never got bored of it :D
"Nevertheless, the gyroscope also reacts to a change in position during uniform rectilinear movement."
I don't understand that at all :) How can anything react to movement with Eq. primary movement? Wouldn't that contradict the equality of all inertial frames of reference?
But it's already after midnight :D So maybe don't think about it anymore.
Except that if it's anywhere in iOS 7, it's only on the start screen. I haven't really noticed it elsewhere. So I wouldn't see it black with the battery consumption. After all, the endurance of iOS 7 compared to iOS 6 is almost the same, if not better (beta5)
Then, for example, in Safari tabs.
even on the lock screen the animated wallpaper moves using this "technology" or whatever you call it
Great article!
The aero app is now free
Contains the above-mentioned effect :)