Use Coordinate Systems with Vision Assistant Express VIs

You can create a coordinate system in one instance of a Vision Assistant Express VI and reference that coordinate system in a second instance of a Vision Assistant Express VI.

Complete the following steps to set up a reference coordinate system using the Vision Assistant Express VI.

1. Place the Vision Assistant Express VI on the LabVIEW block diagram.
2. Develop your vision application using the Vision Assistant processing functions.
3. Set up a coordinate system using the Set Coordinate System step. Coordinate system origins are based on feature locations. You can locate features using the following steps: Edge Detector, Straight Edge (Rake), Adv. Straight Edge, Circular Edge (Spoke), Detect Objects, Pattern Matching, Geometric Matching, Clamp, and Geometry.
4. When you have finished developing your application, click Select Controls.
5. Select the controls and indicators that you want to be able to programmatically set in LabVIEW. To use a reference coordinate system in another Express VI instance, you must select the Coordinate System Out control.
6. Click Finish to return to LabVIEW and update the Express VI.
7. Place a second instance of the Vision Assistant Express VI on the LabVIEW block diagram. If you configured a Set Coordinate System step in the first instance of the Vision Assistant Express VI, the Select Coordinate System dialog will open.
8. If you want to use the coordinate system defined in the first instance of the Vision Assistant Express VI as a reference coordinate system in the second instance of the Vision Assistant Express VI, select I want to use a coordinate system defined in the following VI in this Express VI.
9. Select the VI that creates the coordinate system from the drop-down listbox.
10. When the second instance of the Vision Assistant Express VI dialog opens, you will see a Set Coordinate System step in your script. You cannot edit the step in the second instance, but you can delete the step from the script. The Express VI will be created with a Coordinate System in input control. It is your responsibility to manually wire the Coordinate System Out from the first Express VI to the Coordinate System in of the second Express VI.

Considerations

• When you open an instance of the Vision Assistant Express VI that references a coordinate system from a previous instance of an Express VI, Vision Assistant opens with the last image used to configure the coordinate system. You cannot modify the image because the regions of interest you define in subsequent steps must be able to reference the image.
• The image used to define the coordinate system must be available when you edit the Express VI that references that coordinate system. This means you must edit or run the Express VI that defines the coordinate system before editing the Express VI that references the coordinate system.
• If you try to edit the Express VI when an image is not available, Vision Assistant prompts you to either run the VI that defines the coordinate system or disable the repositioning of regions of interest in the steps that reference that specific coordinate system.