If you look at the color spectrum, there are no lines between two different colors except the ones the mind imposes in order to make sense of the world through categorization and conceptualization. The same is true of objects, there is no adherent beginning and end to an object. We impose lines to make sense of things. This is the left brain's job, while the right brain continues to perceive the whole. This doesn't necessarily mean that the categorization is less genuine than unbiased perception. That would be to claim there are no particles, only waves. The truth is a bit more nuanced than that. When quantum physicists tests for particles, they see particles. When they test for waves, they get waves.

But regarding the actual labeling of objects, it is objectively arbitrary and impossible to measure where objects separate or whether the gestalt is something unique to itself. One can only measure which concept of reality is easiest to navigate.