Template Image and Alignment
- 14 Nov 2024
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Template Image and Alignment
- Updated on 14 Nov 2024
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- PDF
Article summary
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Use the Template Image and Alignment page to capture a Template Image as a reference for your inspection program, and use pattern-matching to locate and orient parts for relative inspection.
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Preview
If a Template Image has not yet been captured for this recipe, the preview pane (on the left-hand side) displays a live preview of the camera’s field of vision.
Once the Template Image has been captured, the preview pane will display the Template Image, not a live preview of the camera’s field of vision. To view a live preview from the camera, scroll down the page and select Live Preview Mode. To retake the Template Image, ensure the live preview is not enabled and click Re-Capture Template Image.
Capture/Re-Capture
Re-Capture Template Image: Click to change the Template Image.
Capture Template Image: Click to capture (or re-capture) a Template Image. Capturing a Template Image is a required step for ALL recipes.
Import From Library: Click to select an existing image from the Library as the Template Image.
Note
By default, the Import From Library modal will filter images by Recipe. Use the drop-down menu to select another recipe or clear the filter and click Search to find images from other Recipes.
Skip Aligner
Select to disable the aligner and use fixed-position Regions of Interest. This is recommended for applications with parts that are fixtured or presented to the camera very repeatably.
Template Regions
+ Rectangle / + Circle: Click to add a Template Region to the Template Image. The OV20i will detect edges inside these Template Regions and try to locate parts by matching similar edge patterns. Click on a Template Region to stretch or change the size of the shape, rotate, or delete. Click and drag the Template Region to reposition it.
Ignore Template Region: Click to access a brush tool that can be used to erase unwanted edges from any Template Region. This is used to mask out unwanted edge noise and focus the Alignment on clear, repeatable edge patterns. Click Finish to save.
Settings
Rotation Range: Enter an angle of 0-180 degrees to define the amount of rotation the aligner will tolerate. Set this to 180 to find parts rotated at any angle. Set this to 0 to find only parts that match the Template Image angle.
Sensitivity: Adjust the slider to increase/decrease edge-finding sensitivity. Higher sensitivity settings will find more edges, and lower sensitivity settings will find fewer edges.
Confidence Threshold: Use this slider to set the minimum confidence required for an Alignment to be considered valid (1% indicates an identical match). This threshold should fall between 0.6-0.9 for consistent alignment.
Live Preview Mode
Select to run the aligner in real-time allowing you to test its performance and confidence on different situations and parts.
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Alignment Best Practices
Alignment Best Practices
When placing Template Regions, focus on edges that are simple, unique, and consistently visible across all parts. Try to avoid edges that may be obscured by defects, or edge patterns that vary from part to part.
Edges found inside a Template Region are highlighted green. Red highlights indicate that there are not enough edges found for valid alignment. You can increase sensitivity or add more Template Regions to increase the edge count (below).
Use the Ignore Template Region tool to filter out edge noise from the Alignment. “Edge noise” includes any highlighted edges that do not represent a simple, unique, and consistently visible pattern. For example, a Template Region might inappropriately highlight textured surfaces, reflections, debris, or other features as edges in your Template Image.
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In this example, we are attempting to align to some of the white outlines printed on the circuit board, because they should be visible even if other components are broken or missing. In this case, the 1st Template Region does not have enough edges.
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Adding more Template Regions increases the number of edges for Alignment. In this case, a 2nd Template Region has been added over the circular feature in the lower left corner, but the highlights remain red because not enough edges are found.
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Increasing the sensitivity finds more edges in the existing Template Regions. It’s recommended to use the lowest Sensitivity setting that still finds adequate edges to avoid unwanted noise in the pattern.
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Left: Before using the Ignore Template Regions tool, the edge finder highlights some shiny areas and resistor edges that are not simple, unique, and consistently visible. Right: After applying the Ignore Template Regions tool, the unwanted noise is masked by the red regions so the aligner will only pay attention to the white printed line patterns.
Tips
If Alignment is inconsistent or fails when testing on different parts, your Template Regions may be set up on a pattern that is not simple enough, or not consistently visible across all parts. Try reducing the amount of edges, or choosing a different pattern to focus on for Alignment.
If Alignment has frequent “false positives” where it matches to something other than the part you want to find, you may have chosen a pattern that is not unique enough. Try increasing the Confidence Threshold to screen out the false positives, or add Template Regions and/or Sensitivity to make your Alignment pattern more specific.
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