When I first arrived in NY I lived on the upper east side. My building was on 74th and Lex. I had a corner apartment so my bedroom looked south and west, it got sunlight for most of the day.
When I worked with a model, I always painted in the apartment and the bedroom; because of its light, it was a favorite place to work. Later when I moved and had a studio, I wondered what an observer on the other side of the street would have seen if they had looked through my bedroom window when my models were posing. I had sketches of the models from that time and using them I imagined this.