Calculate Occlusion

In any triangulation based 3D vision system occlusion can occur. In the illustration below we show how one object can be hidden behind a taller object.

Occlusion as a function of baseline

In stationary mounted bin-picking or piece-picking the bin walls or dividers can create this situation. If the camera is looking at two compartments then occlusion can be avoided by aligning the camera baseline with the shared wall or divider. If there are more than two compartments no such alignment is possible. For example:

  • picking from more than 2 bins

  • picking from a bin with 2 or more dividers

larger baseline ➞ worse occlusion effect

2 bins, negligible occlusion

Occlusion avoided with only two bins

Top view

Occlusion avoided with only two bins

Side view

4 bins, unavoidable occlusion

Occlusion unavoidable with more than two bins

Top view

Occlusion unavoidable with more than two bins

Side view

The following calculator shows the occlusion effects across a single wall or divider. The camera is positioned directly above the wall such as to minimize the worst case occlusion. You can see that the occlusion is symmetric across the wall.

Select camera:
Camera baseline: 111.83 mm
20 600
Select bin:
Bin depth: 600 mm
201200
Distance to top of bin: 1000 mm
1002000
Occlusion for 600 mm deep bin @ 1000 mm with 111.83 mm baseline camera:

33.5 mm

Side view visualization: