The Training Mask allows users to manually remove unwanted edges from the trained model. When a model is trained, all the edges within the trained area are counted as edges for the model. Many of these edges may be unwanted edges.
You can choose the areas to mask by using the drawing tools to color over all unwanted green edges with the red mask. For example, you may choose to color over all edges that are the result of glare, or shadows, or unwanted features in the background. Removal of unreliable edges will improve the score of the GPM Locator. When masking edges, use the image zoom to finely tune the mask.
While running production, watch the Vision Runtime screen and note any edges consistently shown in red, and manually remove them from consideration, using the Training Mask.
When [Enable] is unchecked, the mask is ignored.
If a feature found in the model pattern is missing from the pattern in the image, the GPM Locator Tool judges that the pattern is different by as much as that missing feature. On the other hand, however, the tool ignores extra features. Therefore, if there is any extra feature that happens to exist in the image when the model pattern is taught, it is desirable not to include that feature in the model pattern.
The GPM Locator Tool allows you to mask a specific part of the image and to remove that part from the model pattern after the model pattern teaching operation. This process is called "masking the model pattern". If the image taught as a model pattern includes any of the parts described below, mask those parts and remove them from the model pattern.
- <1> Part where the distance from the camera differs
- When you see an object through a camera, what is known as "parallax" occurs. Even when an object is moved linearly by the same amount in the actual space, the amount of travel in the image seen via the camera varies, if the distance from the camera to the object is different. This difference in the amount of travel is called parallax.
- When you move an object having a certain height, the distance from the camera differs for the top andbottom of the object and the amount of travel seen via the camera varies due to parallax. This means that moving the object results in changes not only in position but also in geometry in the image.
- For example, consider a glass like the one shown in Fig.(i).
If you place the glass so that it comes near the center of the image, the camera views the glass from right above and the resultant pattern is a concentric double circle as shown in Fig.(ii). If you place the glass so that it comes to a corner of the image, however, the resultant pattern is an eccentric double circle due to the parallax effect as shown in Fig.(iii). Since the patterns in Fig.(ii) and Fig.(iii) differ in geometry, the pattern in Fig.(iii) cannot be found even if the pattern in Fig.(ii) is taught as the model pattern.
- To avoid this problem, any part where the distance from the camera is different must be masked and removed from the model pattern. In the case of the glass, mask either the outer or inner circle.
- As described earlier, the GPM Locator Tool allows distortion between the model pattern and the pattern in the image as long as the distortion is within the allowable range. If the difference in geometry caused by parallax is within the allowable range of distortion, the GPM Locator Tool can find the pattern.
Also, widening the distance between the camera and the workpiece helps alleviate the effect of parallax.
- <2> Part that looks differently for each workpiece
- When you capture an image of a workpiece via the camera, the image sometimes might contain a feature, such as a blemish, that looks different for each workpiece or each time the position of the workpiece is changed. The GPM Locator Tool pays attention to such features as well when searching the image for a pattern identical to the taught model pattern. Therefore, removing these features from the model pattern helps the tool find matching patterns more accurately.
- Mask the following parts to remove them from the model pattern.
- Blemish on the workpiece
- Unevenness on the workpiece surface (e.g. casting surface)
- Part that happens to appear aglow
- Shadow
- Hand-written letters and marks
- <3> Part where dark/light polarity is irregular
- When the position or orientation of an object is changed, the way the object is illuminated and how shadows are cast on it might change as well, thus altering the dark/light polarity of the figure in the image. As described earlier, the GPM Locator Tool considers a pattern different if its dark/light polarity is different.
- When you snap images of actual workpieces, it is often the case that the dark/light polarity appears reversed in some parts of the pattern although the overall dark/light polarity of the pattern remains unchanged. These parts look different for each workpiece, as described in <2>, and removing them from the model pattern helps the tool find matching patterns more accurately.