16
Annex
16.1
Range (3D) measurement
The 3D camera measures range using triangulation. This means that the object is
illuminated with a line light from one direction, and the camera is measuring the object
from another direction.
The camera analyzes the sensor images to locate the laser line in them. The higher up
the laser line is found for a point along the x-axis (the width of the object), the higher up
is that point on the object.
4
1
2
x
y
z
3
Figure 85: Coordinate system when measuring range
1
Transport direction
2
Range (Z)
3
Negative transport direction (Y)
4
Width (X)
The following is important to get correct measurement results:
•
The laser line is orthogonal to the movement direction of the object.
16.1.1
Occlusion
Occlusion occurs when there is no laser line for the 3D camera to detect in the sensor
image. Occlusion will result in missing data for the affected points in the measurement
result.
There are two types of occlusion:
Camera occlusion
When the laser line is hidden from the camera by the object.
Laser occlusion
When the laser cannot properly illuminate parts of the object.
ANNEX
16
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