When you annotate an object with obfuscation like here:
Sometimes you create partial masks or polygons as something in front
is "breaking up" the annotation in the background. However, this is
less-than-optimal for machine learning networks as it causes confusion.
To that, you can either create the background annotation as one uniform
annotation using the brush like this:
Or you can merge separate masks or polygons into one shape by first
selecting all of them, and then click "Merge into single mask" (at the
top in the annotation view).
The final result will be a uniform mask (if you selected multiple
polygons, we will convert them to one mask annotation, as polygons
should never be used to annotate multiple regions) like here: