For physical depth:
* Shallowness
* Superficiality
* Surface
* Height (in the sense of vertical distance from a surface)
For emotional depth:
* Superficiality
* Shallowness
* Simplicity
* Lack of complexity
* Flippancy
For intellectual depth:
* Simplicity
* Superficiality
* Lack of understanding
* Ignorance
For artistic depth:
* Superficiality
* Lack of substance
* Clichéd
* Unoriginal
It's important to consider the specific context to determine the most accurate opposite.