The definition of Depth in VL53L TOF sensors

[Yunlion]

Hello, 

I have a FUNDAMENTAL question: TOF VL53 series  sensors report a depth map. Is the depth the "Euclidean distance from the origin (0, 0, 0) to the point (X,Y,Z)" ? or is the orthogonal distance from the camera chip plane to the measured point along the optical axis?? if we use, x y, z  ( z is the sensor chip surface normal direction, i.e., the optical axis) to represent the measured point, the first case is depth^2= x^2+y^2+z^2, The second case is depth=z.

Anyone can give me a concrete proved answer? Many Thanks to you in advance!!

[John_Kvam]

This is a big deal on ST's multizone sensors. They convert the radial distances seen into perpendicular distances. 

This rad-to-perp function is inside the sensor, so what you get are the orthogonal distances. 

On the VL53L5, L7 and L8 sensors, if you point the sensor perpendicularly to a wall you will get all the same distances. (Although, getting that sensor exactly perpendicular to a wall takes a bit of doing.)

In the single zone sensors (VL53L0, L1, L3 and L4) only one distance is returned, and it's an average of all the photon distances, so it's not such a big deal. 

ST built these sensors to focus a cellphone camera, and it was determined that this was the best way to go about it.  

It freed the phone from having to do the conversion. 

- john