Superimpose:

 to place or lay (one thing) over another,
typically so that both are still evident:

On the first sunny day of 2015, this is the first and last self-portrait I shot.

* * *

As sequences of lines or curves;

or, a self-portrait in the lobby of a dark hotel when outside it is daylight;

or, spontaneously found words from the wikipedia page on Superimposition.

Parallel features embed something compromised,

century of already-existing.

Forming another layer may give rise

to periodic killing of small-scale differences.

Such acceleration is known as:

image on top.

At a small speedup, angles appear,

the original mask in linear movement --

the aerial in parallel, overdubbing cartography

and something such as when.

For use of a different face,

existence without completely erasing:

the complex scatter/conceal.

Crude symbols result in faster movement.