Справочник Пользователя для National Instruments IMAQ Vision for LabWindows TM /CVI
Chapter 5
Performing Machine Vision Tasks
5-4
ni.com
Using Edge Detection to Build a Coordinate Transform
You can build a coordinate transform using two edge detection techniques.
Use
Use
imaqFindTransformRect()
to define a coordinate system using
one rectangular region. Use
imaqFindTransformRects()
to define a
coordinate system using two independent rectangular regions. Follow these
steps to build a coordinate transform using edge detection.
steps to build a coordinate transform using edge detection.
Note
To use this technique, the object cannot rotate more than ±65
° in the image.
1.
Specify one or two rectangular ROIs.
a.
If you use
imaqFindTransformRect()
, specify one rectangular
ROI that includes part of two straight, nonparallel boundaries of
the object, as shown in Figure 5-2. This rectangular region must
be large enough to include these boundaries in all the images you
want to inspect.
the object, as shown in Figure 5-2. This rectangular region must
be large enough to include these boundaries in all the images you
want to inspect.
Figure 5-2. Coordinate Systems of a Reference Image and Inspection Image
1
Search Area for the Coordinate System
2
Object Edges
3
Origin of the Coordinate System
4
Measurement Area
1
4
1
4
a.
b.
2
3
3
2