When an artist draws from an image in their brain (instead of from observation), they are using a?

In 1907, the retrospective on the work of 19th century post-impressionist georges seurat influenced the development of cubism in a radical way through his painting titled, “sunday afternoon on the island of la grande jatte.” ? ?

1× 10×10×10+2×30×30=[tex]1 \times 10(4) + 2 \times 10(3) = \\ [/tex]

What is the name of the piece above?