Measure Feature Point Height

Description

This Step is used to locate the feature point(s) of the profile and measure the height of feature point(s) relative to a reference line or a base point.

Workflow

The process of configuring this Step is shown below.

measure feature point height

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

  2. Set the feature region.

  3. Set other parameters.

  4. Select the desired output(s) under Output. For an expandable output item, click ▶ and configure the Min and Max values of the acceptable range.

  5. Run the Step and view output.

Parameter Description

Feature Region

This parameter is used to add feature regions (1–16) for locating feature points on the profile.
Reference Line

When this parameter is selected, a reference line will be fitted using the data within the set line region(s).

  • Line Regions (1–2): This parameter defines a region on the profile, and the data points within the region will be used to fit the reference line.

  • Fitting Method: The method of fitting a reference line with the defined reference region. Choose between Simple and Robust.

    • Simple: High speed, but low accuracy.

    • Robust: An iterative fitting method. High accuracy, but low speed.

      • Outlier Fraction: The proportion of outliers to be removed during line fitting, thus resulting in a better result.

Use Base Point

This parameter defines a region for locating a base point, which facilitates the measurement of feature point height.

  • Base Point Region: Configure the base point region by adjusting Center X / Z, Width, and Height of the base point region.

  • Feature Point Type: Select a type of feature points within the region as the base point. For more information, please refer to Feature Point Types.

Height Measurement Method

There are four ways to measure feature point height, corresponding to the following four calculation methods. You can choose among them according to the actual measurement requirements.

Feature Region Only

It is possible to set 1–16 feature region(s), and the 1–16 feature point height(s) can be measured at once. In this case, take the line with Z = 0 as the reference line, and calculate the distance from the feature point to this line as the feature point height. The height is positive for points above the line and negative for points below the line.

only feature regions
Feature Region + Reference Line

Calculate the distance from the feature point to the reference line as the feature point height. The height is positive for points above the line and negative for points below the line.

feature regions plus line
Feature Region + Base Point

Make a reference line parallel to the X-axis through the base point, and calculate the distance from the feature point to the line. The height is positive for points above the line and negative for points below the line.

In this case, the base point height is the distance from the base point to the line with Z = 0.

feature regions plus base point
Feature Region + Reference Line + Base Point

Make a line parallel to the reference line through the base point, and calculate the distance from the feature point to the line. The height is positive for points above the line and negative for points below the line.

In this case, the base point height is the distance from the base point to the reference line. The height is positive for points above the line and negative for points below the line.

feature regions plus line plus base point

Output Description

Select the output item(s) according to the actual measurement requirements. Then the corresponding data will be output after the Step is run.

If you select an expandable output item, you must 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

Height of Feature Point

The height of a feature point to the reference line or that of a feature point to the base point. The height is positive for feature points above the reference line or base point, and negative for feature points below the reference line or base point.
Without reference line and base point, the feature point height is the distance from the feature point to the line with Z = 0.

Height of Base Point

Without reference line, the base point height is the distance from the base point to the line with Z = 0.
With a reference line set, the base point height is the distance from the base point to the reference line. The height is positive for points above the line and negative for points below the line.

Troubleshooting

Invalid Type

No. Error Possible Causes Solution

1

Invalid feature point type

The feature point type is not selected properly.

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

Invalid Parameter

No. Error Possible Causes Solution

1

Incorrect setting of percentile

The value of “Low Percentile” is greater than that of “High Percentile,” or either of them is not within 0–100%.

Reset the percentile to ensure that the percentile is within 0–100% and that the value of “Low Percentile” is lower than that of “High Percentile.”

2

Inappropriate setting of “Outlier Fraction”

The set outlier fraction is not within 0–100%.

Reset “Outlier Fraction” to ensure that the value is within 0–100%.

3

“Index” value out of range

-

Adjust the “Index” value to ensure that it is no greater than the number of turning points.

Invalid ROI

No. Error Error Description Possible Causes Solution

1

Insufficient data points defined by the Region2

When the feature point type is “Contact,” there are not enough points in Region2, and thus circle fitting failed.

The number of points in Region2 is smaller than 3, which leads to the failure of circle fitting.

Adjust Reon2 to ensure that the number of points in it is equal to or greater than 3.

2

No point of “Contact” detected

When the feature point type was set to “Contact,” no valid points of contact were detected.

The fitted line and circle are separated.

Adjust the feature region to ensure that the fitted line and circle intersect or are tangent.

3

Insufficient data points defined by the Region2

When the feature point type is “Intersection,” there are not enough points in the Region2, which leads to the failure of line fitting.

If the number of points in Region2 is less than 2, no line can be fitted.

Adjust the feature region to ensure that the number of points in Region2 is equal to or greater than 2.

4

No point of “Intersection” detected

When the feature point type was “Intersection,” no point of intersection was detected.

The fitted two lines are parallel.

Adjust the feature regions to ensure that the fit two lines can intersect.

5

No point of “Inflection” detected

-

  • The “Sensitivity” value is too small.

  • The “Inflection Type” was not selected properly.

  • The profile in the feature region is too flat, and there is no point of inflection.

  • Increase the value of “Sensitivity” appropriately.

  • Select a valid “Inflection Type.”

  • Reset the feature region to ensure that at least a valid point of inflection can be generated.

6

Insufficient data points defined by reference region(s)

When the “Reference” option is selected, there are not enough points in the line region(s).

The number of points in the line region(s) is smaller than 2, which leads to the failure of line fitting.

Adjust the line region(s) to ensure that the number of points in the region is greater than or equal to 2.

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