Head mounted displays are wearable three dimensional displays for information viewing applications. Head mounted displays were introduced in the 1960s as an entertainment device for directly streaming movies.
The virtual environments are used in a wide array of applications that includes consumer electronics, military simulations, medical training and virtual prototyping among many others.
4D printing is the three dimension printing of any material of any prototype with time as its fourth dimension. The created component structure grows or modifies as the time passes.