What does Just Dance 2017 score via Kinect?

I just joined my kids for a few rounds of Just Dance 2017 on X-Box One using the Kinect controller, and I am wondering if anybody has determined what the game sees and how it uses it to score players?

I discovered that just swinging my arms randomly in time with the music produced scores as high as my kids, who appeared to be closely following the moves of the model dancer. Also, when using the Kinect controller, each player is rendered on-screen as a tiny two-dimensional silhouette. Is that what the game uses to score players? (Because if so then any hand movements in front of the body would be unreadable.)