Since around 2015, speculation has been circulating about a self-driving vehicle that Apple was supposedly developing and would bring to market in 2020. Well, it's 2020 - a year that has defied expectations in many ways - and nobody has spoken of the iCar for a few years. We now know that Apple is focusing on developing in-car software rather than the cars themselves.

But one technology has made it from Project Titan (the iCar project) into a real Apple product. This one hasn't got four wheels, but it has got four cameras - or rather, three cameras and a mysterious fourth imaging system. It's the iPad Pro, and that imaging system is LiDAR.

The same system has since made its way into the iPhone 12 Pro handsets for autumn 2020, which means it's suddenly gone mainstream. But what's LiDAR all about, and is it worth having?

What is LiDAR?

The acronym is generally agreed to stand for "light detection and ranging", although variants are sometimes used. In contrast to radar, for example, it's based on laser light, which is why the technology is also occasionally referred to as LaDAR, or "laser detection and ranging".

LiDAR uses the reflection of electromagnetic waves to measure and map 3D space. It emits light, which is then scattered back from objects and detected by the system.

The frequency of the light changes when the object and detector are not at rest relative to one another, which allows the system to measure speed. In fact, both object distance and speed can be measured much more precisely with LiDAR than with radar's radio waves.

What is LiDAR used for?

Originally designed for measuring the atmosphere - conclusions can be drawn about aerosols and dust particles in the air based on the transit time of the backscattered light - LiDAR is now the technology of choice for self-driving vehicles, which have to precisely detect objects in their vicinity, their speed, and their distance from the vehicle.

On a similar note, the tech is also used for traffic-control speed guns.

In the iPad Pro and especially in the iPhone 12 Pro, the LiDAR is of course assigned other tasks; you can forget the idea that an iPhone in the windshield will turn your old car into an autonomous vehicle.

What are the benefits of LiDAR for an iPhone?

Apple's product description says LiDAR has a measurement range of 5m indoors and outdoors: this means that within these parameters, iOS 14 and the A14 Bionic processor can use the LiDAR scanner's data to calculate an exact spatial image of the environment.

This has many practical applications - just think of photography, and the challenge of separating background from foreground, or autofocusing shots in low light. The dual- and triple-lens camera setups in the previous iPhone generation do a pretty good job together with the CPU, but performance will be even better when combined with LiDAR.

Above all, however, LiDAR will be used to raise the AR (augmented reality) capabilities of the iPhone 12 Pro to new levels. It will be possible to build virtual objects into real environments, and vice versa, with high precision. iOS's virtual tape measure will be able to measure objects much more accurately.

Anyone who's ever had a room measured by a craftsman will be familiar with LiDAR devices - even if they didn't know at the time what they were called - and will realise that the technology's laser light cannot be seen because LiDAR works in the near-infrared range. The power of the radiation is also so low that people nearby don't have to worry about their eyes.

This article originally appeared on Macwelt. Translation by David Price.