ToF for scanning doesnt work as desired

[Isaac Ng]

Recently i was using the STM vl6180x tof sensor to scan objects to obtain their shape. Referring to the object i drawn, it was supposed to be a sharp 90 degree shape (from point 1 to point 2) but the tof sensor gave a slope/curve that doesnt really shows the shape of the object.
Experiment setup: i move the sensor across the object which means i'm scanning in a straight line. Kindly advise what is going on with the sensor and how do i improve this thing.

[Yveaux]

@isaac-ng said in ToF for scanning doesnt work as desired:

vl6180x

I've not used this particular sensor, but judging from the datasheet it uses IR led illumination and has a 42 degree field-of-view (http://www.st.com/content/ccc/resource/technical/document/datasheet/c4/11/28/86/e6/26/44/b3/DM00112632.pdf/files/DM00112632.pdf/jcr:content/translations/en.DM00112632.pdf, chapter 2.10.1).
It probably 'averages' the distances measured withing its field-of-view, causing a gradual transition from distance 1 to distance 2.

If you really need a step response in the measured distance you'd likely need a sensor with a very small field-of-view, e.g. a laser bundle.
On the other hand, the point with the maximum slope in the transition from 1 to 2 will probably be very close to the actual step in your shape.