Locate Feature Point of Profile

Description

This Step is used to locate a feature point from the input profile, such as a point with a maximum or minimum Z value.

Workflow

The process of configuring this Step is shown below.

locate feature point of profile

  1. Configure the input. Connect the ports manually in the graphical programming workspace or select the input(s) under Input in the parameter configuration panel.

  2. Determine whether to use a feature region. For more information on the configuration of feature region, refer to Instructions on Feature Region.

  3. Select the desired output items under Output. For an expandable output item, click ▶ and configure the Min and Max values to set the acceptable range.

  4. Run the Step and view output.

Parameter Description

Feature Point Type

This parameter determines the type of the feature point to be located from the profile.

For more information on feature point types, see Feature Points.

Use Feature Region

This parameter defines the region within which the feature point can be selected. For more information on how to set the feature region, see Set the Feature Region.

Default setting: unselected

Instruction: Set the parameter according to the actual requirement.

Epsilon

This parameter specifies the sensitivity to profile shape changes. Generally, the smaller the Epsilon value, the more candidate feature points are calculated in the feature region, indicating higher sensitivity to profile shape changes. Conversely, the larger the Epsilon value, the fewer candidate feature points are calculated in the feature region, indicating lower sensitivity to profile shape changes.

This parameter can be used only when the feature point is a corner or an edge.

Output Description

Check the output item to add it to the Step, and the corresponding data will be output after the Step is run. You can select the output according to the actual measurement requirements.

If you select an expandable output item, you should expand it by clicking ▶, and then set the Min and Max values to determine the acceptable range. If the output value of the measurement item falls within the acceptable range, it is judged as okay (OK), or else it is judged as not good (NG).
Output Item Description

X-Coordinate

The X value of the feature point located from the profile.

Z-Coordinate

The Z value of the feature point located from the profile.

Feature Point

The feature point located from the profile.

Troubleshooting

Invalid Type

No. Error Possible Causes Solution

1

Invalid feature point type

The feature point type was not selected properly.

Select a valid feature point type in the “Feature Point Type” drop-down list.

Invalid Input

No. Error Possible Causes Solution

1

No corner detected

  • The value of “Epsilon” is too large.

  • The input profile or profile data in the feature region is inappropriate. For example, if the number of profile points is smaller than 3, or the profile points are collinear, no corner can be detected.

  • Try decreasing the value of “Epsilon.”

  • Replace or adjust the profile data to ensure that the number of profile points is greater than or equal to 3 and that the profile points are not collinear.

2

No rising or falling edge detected

  • The value of “Epsilon” is too large.

  • The input profile or profile data in the feature region is inappropriate. For example, if the number of profile points is smaller than 3, or the profile points are collinear, no rising or falling edge can be detected.

  • Try decreasing the value of “Epsilon.”

  • Replace or adjust the profile data to ensure that the number of profile points is greater than or equal to 3 and that the profile points are not collinear.

3

No rising edge detected

  • The value of “Epsilon” is too large.

  • The input profile or profile data in the feature region is inappropriate. For example, if the number of profile points is smaller than 3, the profile points are collinear, or the profile data does not contain a rising edge, etc., no rising edge can be detected.

  • Try decreasing the value of “Epsilon.”

  • Replace or adjust the profile data to ensure that the number of profile points is greater than or equal to 3, that the profile points are not collinear, and that the profile data contains at least one rising edge.

4

No falling edge detected

  • The value of “Epsilon” is too large.

  • The input profile or profile data in the feature region is inappropriate. For example, if the number of profile points is smaller than 3, the profile points are collinear, or the profile data does not contain a falling edge, etc., no falling edge can be detected.

  • Try decreasing the value of “Epsilon.”

  • Replace or adjust the profile data to ensure that the number of profile points is greater than or equal to 3, that the profile points are not collinear, and that the profile data contains at least one falling edge.

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