# L-Check

L-Check subtask checks if the distance between pairs of features are within specification. It is located under Alignment category in setup mode. L-Check function only supports distance check between point features, line features and generic features are not supported.

Every features finders have an independent L-Check functions, they're arranged in different tab at the top of L-Check setting page. Select one features finder first, then check Enable on/off to enable/disable its L-Check function. The Name besides Enable check box indicates specific sub task in feature finding task which will be enabled or disabled.

L-Check page mainly has four areas: Layout Graphic, Feature Points, Result Display and Measurements. Layout graphic shows all run time features in current features finder and setting points which will be used for length check. Result Display shows the graphics of L-Check in shared coordinate space. Measurements is the panel for user to edit length check points.

To start L-Check setting, click "Auto" button at the bottom of this page to let L-Check automatically generate setting points and measurement points, and update the graphics.

## Layout Graphic

Layout graphic window allows user to load a layout image of the part in format of JPG, JPEG, BMP, TIF or PNG with size under 10 megabyte. This image helps user understand the layout of each feature point on part for convenience of measurement points setting. This image should be drawn by user based on specific part type but not mandatory.

## Feature Points

Feature points displays and manages two sets of points: RunTime Points or Setting Points.

RunTime Points are current run time features of selected features finder. To make them available, the features finder needs to run at least once.

Setting points are the candidate points for measurement. L-Check auto function will make a copy of all run time points and set them as setting points. However, one can change the aliases of the setting points to make them more meaningful.

To preview the changes, click "Preview" button at the bottom right corner under Measurements panel to update the graphics in result display.

## Measurements

Measurements allows user to add, enable/disable, or delete length check between point pairs.

### Add

Click Add button to add one length check. Input its name in the pop-up dialog and click "OK".

Select feature points, input length nominal, upper and lower limits, and offset.

Parameter | Description
--- | ---
Enable | Enable or disable current length check.
Name | Name of current length check.
Feature1/Feature2 | The starting/ending feature points of current length check. Select them from drop list. The order of two points doesn't matter as long as they're not identical.
Nominal | Nominal value of current length
UpperLimit | Upper limit of current length
LowerLimit | Lower limit of current length
Offset | Compensation to measured value

The criteria to judge a length check is:

- Pass: if LowerLimit ≤ (measured distance + offset) ≤ UpperLimit

- Fail: if (measured distance + offset) < LowerLimit or (measured distance + offset) > Upper Limit

### Enable

Disable one length check by checking off its Enable option.

### Delete

Select one length check, and click Delete button.

## Result Display

Result display shows all length check's feature points, nominal values, current values, and differences. Difference indicates how the compensated length (measured result + offset) is different to nominal. If compensated length is within range, then the graphics will be green, otherwise will be red.

When all measurement points are set, click "Preview" button to update the result graphics.

## Reset

To clear setting points and measurement points, click "Reset" button.

## Apply and Save Recipe

When there are any unsaved changes, the "Apply" button is highlighted as "". Click it and select "Yes" to save the changes. After this, the "Apply" button will turn back to "". Go to System/Product Recipe page to save current Alignment sub recipe. Otherwise all the changes will be lost after the program is closed. For more information about recipe, please refer to Product Recipe.

## Run

If a feature finding task's L-Check function is enabled and configured, during run time, after the features are extracted, L-Check will check the configured lengths of the part. If a length is out of specification, the Result Display will show it in red, and the feature finding task will throw an exception; otherwise, If all length checks are passed, then their graphics will be displayed in green, and no exception will be thrown.