Instructions To Reproduce the 🐛 Bug:

1. model has predicted segmentation masks with holes. (white area are predicted mask)

2. When Visualizer.draw_instance_predictions() create GenericMask and call Visualizer.overlay_instances

3. Visualizer.overlay_instances draws mask with "polygon" formate, which considers the holes inside the prediction (which have it own polygon) as part of the prediction.

4. This would induce result like this, where the holes are also considered as predicted area.

5. This is mainly because when the class::GenericMask return the polygon, it does not consider the hole information

and this have to do with cv2.findContours(mask.astype("uint8"), cv2.RETR_CCOMP, cv2.CHAIN_APPROX_NONE) return holes inside the mask but there's not subsequrnce operation to filter out those polygon