Generating Models And Detecting Orientation; Setting For The Precision Parameter - Siemens SIMATIC VS120 Operating Instructions Manual

4.3

Generating models and detecting orientation

4.3
A model is created from the sum of the edges extracted in the image and their arrangement.
To ensure good processing quality, the contours of the model should lie within the ROI
(Region of Interest).
4.3.1

Setting for the Precision parameter

The precision setting is based on the size of the ROIs and recognizable changes in the
specimen. The search for a part in the image is "pyramidal". It starts with a coarse search at
low resolution and finishes with a fine search at high resolution. The Precision parameter
affects the coarse and fine search.
Coarse and fine search
The table shows the start and end values of the resolution during the search process with
the various levels of precision.
Precision level
Fine1
Fine2
Fine3
Medium1
Medium2
Coarse1
Coarse2
The precision for determining the position should be set as follows:
• "Fine" for the sub-pixel range
• "Medium" for +/-1 pixel and +/-1°
• "Coarse" for +/- 2 pixels and +/-1°
Vision Sensor SIMATIC VS120
Operating Instructions, Edition 02/2006, A5E00757507-01
– The precision for determining the position still depends on the pattern size and the
number of edges found in it and may therefore deviate from the values shown above.
– The angle precision can be increased to < 1° with the "Angle Precision" parameter in
"Options - Extras tab".
Note
If the setting is "Fine1" and the model is large, the processing times may be several
seconds.
4.3 Generating models and detecting orientation
Start value for the resolution
Width x Height (in pixels)
320 x 240
160 x 120
80 x 60
80x60
40x30
40x30
20x15
Image processing
End value for the resolution
Width x Height (in pixels)
640 x480
640 x480
640 x480
320 x 240
320 x 240
160 x 120
160 x 120
4-5