Reference Manual
Chapter
3
Ruler E
Configuring the Ruler
3.7
Details on 3D Profiling Algorithms
This section contains basic information on how the measurement algorithms works and
further details.
Laser Impact Position on the Sensor
The basic function of all the 3D measurements is to compute the impact position of the
laser line for all columns of the selected Region-of-Interest. The light intensity distribution
from the laser line along a sensor column across the laser line can be described as in the
following figure.
Figure 3.5 – The impact position of the laser in one column
The laser line will produce a distinct light peak distributed over a number of pixels along
the sensor column. The center of this peak will be defined as the impact position of the
laser line on that sensor column, which is the range value.
Threshold
Digitizing an analog signal by the means of a binary threshold is a common technique in
signal/image-processing.
The signal in the previous figure can be thresholded by defining an intensity threshold. This
operation will produce a result in which all pixels with an intensity above the threshold will
be defined as logical ones. Pixels with intensity below the threshold will be defined as
logical zeros. This will form a digital representation of the analog signal represented by a
group of logical ones and zeros.
Figure 3.6 – Digitalizing one column of the sensor image using a binary threshold
The width of the laser light peak is defined as the number of pixels representing the peak
with intensity above the threshold.
Intensity
Sensor row
ROI end
ROI start
Intensity
Threshold
Sensor row
ROI end
ROI start
Sensor row
ROI end
ROI start
SICK IVP • Industrial Sensors • www.sickivp.com • All rights reserved
27
