Google employees roamed the streets in the US, offering $5 gift certificates in exchange for a facial scan, The Verge reported on Monday.
Google confirmed it conducted "field research" to collect face-scanning data in order to improve its algorithms.
"Our goal is to build the feature with robust security and performance. We are also building it with inclusiveness in mind, so as many people as possible can benefit," a Google spokesperson was quoted as saying.
"Google is collecting infrared, colour and depth data from each face along with time, ambient light level, and some related 'task' information," said the report.
The face data will be kept for 18 months.
Google Pixel 4 and Pixel 4 XL are slated to release in October.
Likely to feature 6GB RAM, the Pixel 4 phones would feature taller displays.
According to reports, the Pixel 4 device would come with a square camera module at the back, which would house a dual rear camera setup while until now all Pixel models only had a single camera sensor at the back.
Reports also suggested that the phones would have a 3D face unlock module at the front, or both.
The device would be powered by Snapdragon 855 chipset and run the upcoming Android Q operating system (OS).
( With inputs from IANS )