several hatchings such as cross lines and dots are used to represent the depth within this portrait. as seen in this image the darkness of an area is shown by doing a much more of a closer/tight hatchings.
Stunning Pen Drawings Created with Thousands of Tiny Dots! Using thousands upon thousands of tiny dots, Spider Money produces gorgeous artworks that are awe-inspiring in their detail. The Bangkok-based creative wields a mighty Micron pen and draws fancy flourishes with photo-realistic depictions of eyes, noses, and lips.