The Xiaomi Mi Mix 3 could have had a ToF sensor, but here’s why it didn’t

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Time of Flight (ToF) sensors have been grabbing headlines in the past few weeks. Previous devices like the Oppo R17 Pro and the Honor View 20 have featured ToF sensors on the back, while upcoming devices like the LG G8 will feature a ToF sensor on the front. Opinion in the industry is divided — while devices are coming out with this technology, others consider this technology as a gimmick intended to fleece customers.

For instance, the Oppo R17 Pro has a 3D ToF sensor, but GSMArena in their device review called it “downright useless” as Oppo has not provided any software or features to complement its existence; Oppo themselves downplay the existence of this sensor in most of their marketing materials. Honor View 20’s ToF sensor gives you access to features like 3D gaming, AI calorie counting and 3D shaping — all of which are not features that you would probably be using on a daily basis once the honeymoon period for the phone is over.

Xiaomi’s Product Director Mr. Wang Teng Thomas talked about the current state of ToF sensors in a Weibo post. He explained the principles behind the ToF technology and went on to explain that ToF setup consists of three parts: the light source (laser emitter), the lens and the photosensitive element.

As far as advantages go, 3D Time of Flight sensors have decent coverage distance, as they can obtain effective and real-time depth information within 5m. They can also work effectively in a wide range of scenarios, irrespective of strong or weak ambient light around the object. These sensors also have high distance accuracy, with variance of as little as 1 cm.

However, Mr. Thomas also listed out the disadvantages. Current mainstream ToF sensors for smartphones have low resolution (180*240, 240*320, 240*480), so the “X/Y resolution at close range will be relatively low”. The sensor also is power hungry and generates a lot of heat, which is a practical constraint against its prolonged use in smartphones. The ecosystem surrounding the technology is also in its nascent stages, as you also need proper software and applications to actually make creative use of the information gathered by the sensor.

Mr. Thomas mentions that Xiaomi was and is also invested in researching and developing this technology. In fact, certain pre-production prototypes of the Xiaomi Mi Mix 3 did indeed try it out. But because of the low resolution of the sensor and its limited use, Xiaomi decided to continue R&D into the technology instead of opting to ship it with the Mi Mix 3.

Mr. Thomas hopes that 3D ToF sensors can be presented to consumers in the future with a “more complete user experience” that actually brings utility to the consumer.