Time-of-Flight Sensor - a Breakthrough in 3D Scanning?

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Although the principle of Time-of-Flight (ToF) sensor is a long-used 3D method, it is now getting attention of mobile phone owners with high-quality cameras. What is this method of acquiring 3D data and what news does it bring to the world of smart devices?

What is a Time-of-Flight (ToF) sensor?

Time-of-Flight is a type of sensor that measures the distance between itself and all objects that fall within its viewing angle, using light beams or ultrasound. However, light beam is used more often for this measurement method as it offers higher speed and larger bandwidth compared to ultrasound. Using the infrared spectrum also reduces the amount of noise, making it easier to distinguish the beam from normal daylight.

A distance sensor based on audio signals is also referred to as an echolocator. For example, bats and dolphins commonly use this method in nature.

The time-of-flight sensor has a wide range of use in many fields. It is used to scan objects, navigate inside a building, to detect obstacles, detect gestures for 3D visualization and augmented reality, or even edit digital photos in real-time mode. The time-of-flight sensor is popular not only with IoT devices and drones but also with smart phones.

How does the Time-of-Flight sensor work?

The time-of-flight sensor sends a signal which is then reflected by objects falling within the sensor's angle of view, and then it returns to the receiver in the sensor. By comparing the transmission time and the reception time of each pixel, the system counts the distance of the sensor from the spot, where the signal was reflected. There is a huge number of such signals when the device is moving. Many sensors are therefore able to save power in sleep mode when idle.
Time-of-Flight senzor, princip

The distance calculation is based on the formula mentioned above.

Time-of-Flight for photo enhancement

The time-of-flight sensor is a key to further enhancing the quality of mobile photos. Due to the very precisely measured distance of each pixel from the sensor, the background blur can look more natural. However, for good results, an extremely fine-tuned software is needed to handle this function and to use the sensor data correctly. So at this moment, it depends mainly on the manufacturers of individual phones.

i A time-of-flight sensor that transmits signals from the infrared spectrum can also be used for shooting in low light conditions.
Time-of-Flight senzor; hloubka obrazu

In this image you can see the color-coded distance of the objects.

How is ToF different from other 3D technologies?

Unlike other 3D scanning methods such as stereo shooting or structured light, the Time-of-Flight sensor provides real-time application thanks to up to 160 frames per second. Moreover, this technology is relatively inexpensive and not too complicated to process. It also offers the best resolution of all 3D methods.

Mobile phones with ToF sensor

ToF is actually nothing new. It has been experimented with this sensor for quite a long time. It can be found in the second generation of Kinect motion sensor from Microsoft. It is commonly used for LIDAR scanning of the Earth's surface, for autonomous vehicles or drones .

Time-of-Flight senzor; lidar

The result of LIDAR scanning of the Earth's surface.

Recently, the ToF camera has been gradually getting into a wide range of mobile devices, with the aim of striking photo enhancement or augmented reality. There is also speculation about placing the ToF in the iPhone. However, several mobile devices are already equipped with Time-of-Flight . For example these recent models:

Time-of-Flight v Honoru P30 Pro

The Honor P30 Pro combines a Time-of-Flight sensor with a Leica camera.

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The Time-of-Flight (ToF) sensor is used where it is necessary to accurately measure the depth or distance of an object. But it is also starting to appear in smartphones, helping to improve the overall enjoyment of photography or the use of virtual or augmented reality. In the future, we will hear a lot about the ToF sensor for sure.

Smartphones Mobile phones with Time of Flight sensor