In the cinema (or 'reel' life), images are projected onto a screen. Here a blue rectangle is enlarged by projection using vectors shown in magenta). The centre of enlargement can be translated (dragged) to a new location. The scale factor of the enlargement, n, can be adjusted with the slider (1 [math]\le[/math] n [math]\le[/math]3). The window on the left shows the 2-d view. The window on the right shows the 3-d view of the same enlargement. [br]