It looks like in some cases, a drone with a packet moving on top of a delivery point appears as a skyscrapper. Here a consecutive sequence of frames: <img width="644" alt="Screenshot 2020-02-13 at 14 56 26" src="https://user-images.githubusercontent.com/140592/74420494-89e55300-4e71-11ea-9236-53062ab62062.png"> <img width="644" alt="Screenshot 2020-02-13 at 14 56 33" src="https://user-images.githubusercontent.com/140592/74420501-8ce04380-4e71-11ea-8f87-6c61917b733b.png"> <img width="638" alt="Screenshot 2020-02-13 at 14 56 40" src="https://user-images.githubusercontent.com/140592/74420508-8f429d80-4e71-11ea-864c-078587dbbc2d.png"> <img width="636" alt="Screenshot 2020-02-13 at 14 59 24" src="https://user-images.githubusercontent.com/140592/74420513-910c6100-4e71-11ea-876b-8121599cc1e6.png">
It looks like in some cases, a drone with a packet moving on top of a delivery point appears as a skyscrapper. Here a consecutive sequence of frames: