Warning

You are reading the documentation for an older Pickit release (2.0). Documentation for the latest release (3.4) can be found here.

How to detect an empty ROI

In this article, you will learn a strategy when Pickit no longer detects  objects that allows discriminating between an empty Region of Interest (ROI) from a ROI that still contains parts that are either undetected or of a different type than what Pickit is looking for.

These are the steps to follow:

Create a new product file

In the Configuration section create a new product file (e.g. empty_roi).

Adjust the detection settings

Navigate to the  Detection page and input the following settings:

  • Detection engine: Flex.

  • Group points into clusters: No clustering.

  • Reject clusters by cluster size: Min 200 points. Adjust this number in relation to your part size, as described below in Define the minimum number of points.

  • Fit objects to clusters: Blob.

If you run object detection with this product file and Pickit finds zero objects, the ROI is empty; otherwise, it still has contents inside.

Define the minimum number of points

The following is a strategy for determining the minimum number of points needed to discriminate if the ROI is empty or not. Generally speaking, this number should be lower for smaller parts and larger for bigger parts.

Make sure the product file created above is selected and navigate to the  Detection page and input the following settings:

  1. Reject clusters by cluster size: Min 10 points.

  2. Remove all parts from the ROI.

  3. Run object detection. If there are detections, check the number of points of the detected blob. If the ROI is truly empty, you should get zero detections (zero points).

  4. Add one part to the ROI in a position that faces the camera from its smallest side (i.e. least visible points).

  5. Run object detection and check the number of points of the detected part.

  6. The minimum number of points should a number between the result of steps 3 and 5.

Modify your robot program

If running Pickit object detection with the product file meant to detect your parts returns zero matches, we can check for an empty ROI:

  • Optional: Retry object detection a few times to confirm that no parts are found

  • Switch to the empty_roi product and trigger object detection.

    • If no objects are found, the ROI is empty.

    • If objects are found, the ROI is not empty and contains undetected parts or parts of a different type than what Pickit was looking for.