MeasureMinimumDistance Method
Syntax
CWMachineVision.MeasureMinimumDistance SourceImage, SearchArea, MeasurementAxis, Distance [, CommonEdgeOptions] [, CoordinateTransformation] [, FirstEdgePoint] [, LastEdgePoint]
Return Type
On success, this method returns 0. On failure, this function returns a negative number.
Purpose
Measures a distance in the horizontal or vertical direction, from the center of the search area towards the sides of the search area. This method locates edges along a set of parallel search lines, or rake. The edges are determined based on their contrast and slope.
Remarks
Use this method with U8, I16, and SGL images.
If the MeasurementAxis is horizontal, a vertical hit-line to the object is calculated through the left-most edge detected in the right half of the search area. A second vertical hit-line to the object is calculated through the right-most edge in the left half of the search area. If the MeasurementAxis is vertical, a horizontal hit-line to the object is calculated through the upper-most edge detected in the lower half of the search area. A second horizontal hit-line to the object is calculated through the lower-most edge in the upper half of the search area. In either case, the distance between the two lines found is returned.
This method can overlay on the image returned the position of the search area, the search lines, the edges found, and the result.
Parameters
SourceImage As CWIMAQImage
The input image.
SearchArea As CWIMAQRotatedRectangle
Specifies a rectangular search area.
MeasurementAxis As CWMVAxisDirection
The axis direction in which the measurement is performed.
Distance As Single
On return, the measured distance.
CommonEdgeOptions As Variant
[Optional] A CWMVCommonEdgeOptions object defining the parameters of the algorithm that detects the edge locations and the information that is overlaid on the result image.
CoordinateTransformation As Variant
[Optional] A CWMVCoordinateTransformation object. If supplied, the input search area is transformed using this parameter.
FirstEdgePoint As Variant
[Optional] On return, a CWIMAQPoint object that indicates the left or top nearest edge point to the center line of the input rotated rectangle, depending on the MeasurementAxis.
LastEdgePoint As Variant
[Optional] On return, a CWIMAQPoint object that indicates the right or bottom nearest edge point to the center line of the input rotated rectangle, depending on the MeasurementAxis.
Example
Private Sub Run_Click()
'Inputs to MeasureMinimumDistance
Dim SearchArea As New CWIMAQRotatedRectangle
Dim Options As New CWMVCommonEdgeOptions
Dim Transformation As New CWMVCoordinateTransformation
'Outputs of MeasureMinimumDistance
Dim Distance As Single
Dim FirstEdgePoint As New CWIMAQPoint
Dim LastEdgePoint As New CWIMAQPoint
'Get the search area from the viewer
CWMachineVision1.GetSelectedRotatedRectFromViewer CWIMAQViewer1, SearchArea
'Measure the minimum distance in the horizontal direction
CWMachineVision1.MeasureMinimumDistance CWIMAQViewer1.Image, SearchArea, cwmvHorizontalAxis, _
Distance, Options, Transformation, FirstEdgePoint, _
LastEdgePoint
'Display the measured distance
Text1.Text = Distance
End Sub