Time of Flight (ToF) – Have you ever been curious about how portrait mode works or how your phone can recognise your face? As smartphones get better, they come with more and more sensors that send information back to the phone to make the user’s experience better.
Smartphones today have fingerprint sensors built into the screen, LiDAR, camera sensors that are better and bigger than ever, and on some devices, even Time of Flight (ToF) sensors. But the ToF sensor stands out from the other sensors on your phone, mostly because it affects what we do on our phones in a very specific and unnoticed way.
What Is a Time of Flight (ToF) Sensor?
A Time of Flight (ToF) sensor, also called a ToF camera, is a special sensor that sends out an infrared beam of light and measures how long it takes to come back to the sensor. So it was called “Time of Flight.”
This is a lot like the LiDAR cameras on the iPhone Pro line and the facial detection systems on some smartphones, including the iPhone. In those cases, the device makes an infrared map of the owner’s face and compares it to the person it sees to decide whether or not to unlock the device. Still, ToF sensors and LiDAR are not the same in some ways.
It’s also not a new idea to use reflected light (or sound) to figure out how far away something is. Ultrasonic and infrared (IR) sensors have been around for a long time and do pretty much the same thing, but with a lot less information. The benefits of a ToF sensor are that it can measure things quickly and accurately, has a longer range, and is safe to use.
ToF sensors are relatively cheap to make and use compared to other ways to measure depth in 3D. Also, they don’t need much processing power, which makes them perfect for things like smartphones, where knowing the depth of an object can help with features like portrait mode and processing power is limited.
Several companies make ToF sensors, including Sony, which makes 3D sensors for Apple that use ToF technology. TeraRanger One, Lucid, Adafruit, and ASC TigerCub are some other popular companies that make ToF sensors.
How Does a Time of Flight (ToF) Sensor Work?
As we’ve already said, ToF sensors use infrared light to figure out how far away an object is. A small infrared laser sends out light, which hits an object and comes back to the sensor. By timing how long it took for the light to bounce back and come back to the camera, the sensor can figure out how far away something is.
Since we already know how fast light travels and that it travels exactly twice the distance between the sensor and the object, we can use a simple formula to figure out the distance:
(Speed of light x Time of Flight)/2
Some ToF cameras can also use continuous waves to find both distance and depth by looking for phase shifts in the light that is reflected. Again, you might be able to get a lot of information based on the type of sensor you use. This can be used to make a 3D map of the area around the sensor.
Where Are ToF Sensors Used?
As previously stated, ToF sensors were used as a “depth” camera in many smartphones to assist the device’s main camera in producing higher quality portrait mode photos. The goal of these photos is to simulate a camera lens’s shallow depth of field. ToF cameras and sensors can make a big difference because knowing the depth of different objects in such photos is critical to getting the blurriness of the background just right.
Furthermore, ToF cameras are used in biometric authentication, where a device equipped with a ToF camera can create a 3D map of a face to be used as a reference for unlocking the device. This is essentially how face unlocking technology, such as Apple’s Face ID, works. It’s also more secure than simply comparing two images to see if they match because there’s more data to work with than traditional computer vision algorithms that only work with 2D data.
Because of their object detection capabilities and high polling rate, which can reach nearly 160Hz on some sensors, they are commonly used in electric vehicles and other navigation systems. As a result, they’re ideal for real-time applications like object detection, navigation, and even blurring the background on Zoom calls.
In 3D printing, this ability to tell the difference between the subject and the background is also often used. ToF cameras can easily copy a real-world object in all three dimensions, saving you the trouble of designing it from scratch, especially if it’s a complex structure.
ToF sensors help with object scanning, gesture navigation, and indoor navigation. They also help with 3D imaging and making AR experiences better.
ToF sensors are used in Microsoft’s Xbox Kinect, as well as in other gesture recognition projects, drones, and augmented reality (AR) headsets. Overall, their versatility means that they can be used for anything from a smartphone camera suite to the navigation system of a self-driving car.
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Do You Need a ToF Camera on Your Phone?
Not really.
Computational photography has come a long way, and most smartphones today have software that is good enough to completely separate the subject from the background. Also, when it comes to smartphone photography, the number of megapixels and the size of the camera sensor can be much more important.
ToF cameras used to be common on high-end smartphones, but now they’re mostly found on mid-range devices or on the iPhone Pro line as LiDAR sensors, which are based on the Time of Flight concept.
But a ToF camera on your phone can be useful sometimes, especially for biometric authentication. It can also give you a built-in way to measure distance and give your phone’s photography software more information about depth, which will make your portrait mode shots even better.
Know Your Sensors
More and more sensors are being added to smartphones to make your experience even better. A ToF camera is just another one of your phone’s sensors that you can’t use directly but that can make a big difference in other ways.
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