I understand that the below quote is very correct for the Project Google Tango:
By combining Depth Perception with Motion Tracking, the device can measure distances between points in an area that aren't in the same frame.
Based on the above, below are a few questions:
1. Can ARCore be used to measure the distance as the Project Google Tango does?
2. How accurate is the result in comparison to the Project Google Tango?
Can ARCore be used to measure the distance as the Project Google Tango does?
Yes, ARCore can definitely be used to measure the distances. And ARCore does it quite good with the current version 1.8, although Tango devices made it more accurately.
How accurate is the result in comparison to the Project Google Tango?
ARCore and Tango are parts of the same plan for Google, and that's an important thing to keep in mind. And Google has been using parts of Tango for months in another project, Daydream Standalone. Google's Visual Positioning System that was announced alongside this new Daydream system has its roots in Tango. But ARCore has key difference: ARCore requires a device with just a back-facing camera, and with accelerometer and gyroscope. Tango devices had additionally depth camera besides sensor Fusion. Depth sensor allowed more precise positioning but its working distance was short and depth system drained phone's battery very fast.
Speaking of quality, Google Pixel 3 or Huawei P30 Pro, for example, work much better with ARCore than their counterparts. Why? Because tracking sensors in budget Android phones need a thorough calibration in order to observe a robust AR experience.
Hope this helps.