WorkLink Create: Advanced Object Tracking Settings

               

1. Laplace threshold: Threshold in mm for generating the line-model. This value specifies the minimum depth distance between two neighboring pixels necessary to be recognized as an edge

2. Normal threshold: Threshold for generating the line-model. This value specifies the minimum normal difference between two neighboring pixels necessary to be recognized as an edge. Usually we set this threshold very high, because from our experience normal-based lines can't be recognized very reliably. It might make sense to use lower values for certain models, though.

3. Inlier Ratio Init: This is a quality threshold for validating the tracking result during the initialization phase. The value highly depends on your scenario. If the line-model matches the real object perfectly and there is no occlusion a high value is recommended. However, usually the line-model doesn't perfectly match the real object which is why a lower value might work better. Then again if the value is too low the algorithm might start tracking the wrong object. In our experience it is better if the min Inlier Ratio Init value is higher than the value for min Inlier Ratio Tracking, because it's difficult for the algorithm to recover from a bad initialization.

4. Inlier Ratio tracking: This is a quality threshold for validating the tracking result after the initialization phase. The value highly depends on your scenario. If the line-model matches the real object perfectly and there is no occlusion a high value is recommended. However, usually the line-model doesn't perfectly match the real object which is why a lower value might work better. Then again if the value is too low the algorithm might start tracking the wrong object. In our experience it is better if the min Inlier Ratio Tracking value is lower than the value for min Inlier Ratio Init, because we don't want the tracking to fail after the initialization due to effects like motion-blur.

5. Line search length Init relative: The model-based tracker projects the 3D line-model into the camera image and searches for edge pixels orthogonal to the projected lines. The line Search Length Init Relative specifies the length of the orthogonal search lines in percent relative to the minimum resolution during the initialization and tracking phase. Please use line Search Length Tracking Relative and line Search Length Init Relative in favor of the non relative parameters since these parameters work independently.

6. Line search length tracking relative: Same as line Search Length Init Relative, but used during the tracking phase.

7. Line gradient threshold: Threshold for edge candidates in the image. High values will only consider pixels with high contrast as candidates. Low values will also consider other pixels. This is a trade-off. If there are too many candidates the algorithm might choose the wrong pixels. If there are not enough candidates the line-model might not stick to the object in the image.

8. Key frame distance: The minimum distance between keyframes in mm. The line-model will only be generated for certain keyframes. Therefore a higher value improves the performance at the cost of a lower precision. Lower values cost more performance but increase the precision.

Note: Object Tracking was previously known as Model Tracking.

Learn more: New WorkLink Create: Configuration and Best Practices for Object Tracking. 

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