National Instruments IMAQTM 用户手册

Select ROIs in the images to limit the areas in which you perform the 
processing and inspection. You can define ROIs interactively or 
programmatically. 

Follow these steps to interactively define an ROI:

1.

Call 

CWMachineVision.SetupViewerFor<shapename>Selection

. 

The following 

<shapename>

 values are available: 

Annulus

, 

Line

, 

Point

, 

Rectangle

, and 

RotatedRect

. This method configures the 

viewer to display the appropriate tools for the shape you want to select.

2.

Draw an ROI on the image. Resize or reposition the ROI until it defines 
the area of the image you want to process.

3.

Use 

CWMachineVision.GetSelected<shapename>FromViewer

 

to programmatically retrieve the shape from the viewer.

You also can use the techniques described in Chapter 3, 

, to select an ROI.

Table 5-1 indicates which ROI selection methods to use with a given 
CWMachineVision method.

Table 5-1.  ROI Selection Methods to Use with CWMachineVision Methods

SetupViewerForRotatedRectSelection

GetSelectedRotatedRectFromViewer

FindPattern

MeasureMaximumDistance

MeasureMinimumDistance

FindStraightEdge

LightMeterRectangle

SetupViewerForAnnulusSelection

GetSelectedAnnulusFromViewer

FindCircularEdge

FindConcentricEdge