National Instruments IMAQTM 用户手册

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Figure 5-3.  Locating Coordinate System Axes with Two Search Areas

2.

Choose the parameters you need to locate the edges on the object.

3.

Choose the coordinate system axis direction.

4.

Choose the results that you want to overlay onto the image.

5.

Choose the mode for the method. To build a coordinate transformation 
for the first time, set the 

FirstRun

 parameter to 

True

. To update the 

coordinate transformation in subsequent images, set this parameter 
to

False

.

You can build a coordinate transformation using pattern matching. Use 

CWMachineVision.FindCoordTransformUsingPattern

 to define a 

reference coordinate system based on the location of a reference feature. 
Use this technique when the object under inspection does not have straight, 
distinct edges. Follow the steps below to build a coordinate transformation 
using pattern matching.

The object may rotate 360

° in the image using this technique if you use 

rotation-invariant pattern matching.

1

Primary Search Area

2

Secondary Search Area

3

Origin of the Coordinate System

4

Measurement Area

1

3

2

4

1

3

2

4

a.

b.