INTRO

The Main concept of 2D Package art or Mosaic art is that clusters of similar pixels gets combined to a flat (here the biggest size goes about a square from 5 x 5 pixels)

For some historical background you may read the History part of my Voxelart/3d Pixel article.
In generell the packing of circles is a serious mathematical challenge (it belongs to Hilberts list of the 23 mathematical Problems).
Even though in this case there is another kind of core question but the final optical phenomenon is similiar.

The pieces or squares could be arranged in different angles or chaotical:

SUBSTANCE:

Those Pieces can now be replaced by appropriate sized pictures.

These content you now can vary in resolition:

… and in Chaos. 1.  regular 2. different rotation 3. different scale :

… or in position, scale and rotation at the same time:

ANIMATIONTEST

CONCLUSION

If you use squares this topic is related to pixel/voxel art but it appraoches in a more chaotic way. You don´t have that straight grid. The grid is disturbed by joint squares.

Could be interesting to find some own kind of rythm. Like don´t use every step of size (in my case I used square 1×1 to square 5×5) but get restircted to fixed numbers like in music. And Furthermore wire these rythmical restrictions to a dimensions in space or time.

LINKS

Giuseppe Arcimboldo. This is not realy mosaic but some kind of similiar

Charis Tsevis Mosaic art.
The only artist I found, working with this technique

Circle Packing Algorithm

Image Based Circle Packing script for Rhino

Pictures of Circle Packing used on triangle flats

Very mathematical. But a good overview of possible packings.