Right click on the perspective window and select interactive camera. Here, you can rotate the structure by holding down the mouse left button and moving left and right, and you can view the structure from the bottom or top by moving it up and down. You can zoom in without disturbing the position of the structure by holding down the mouse right button and moving back and forth on the screen. With the ctrl+mouse left key, you can zoom in and out of the structure on a point. With the ctrl+mouse right key, you can increase or decrease the viewpoint. You can also perform similar operations by using shift+left and shift+right key combinations. It is possible to capture the perspective you want with the combinations of ctrl, shift and mouse keys. You will get used to it after a short try.