I think I heard of why it’s like that, let me find it first.
Here it is
if we have a fish floating freely in the sea, we want to define it in explicit terms, clearly defining the forms that make up its body and how they exist in 3D space in relation to one another.
When the fish is stapled to the wall however, this ceases to be the case. As we can have thousands of these fish all lined up against the same surface, if we were to draw each and every one explicitly , not only would it end up being an insurmountable task, it would also look horrible. All that detail would result in a great deal of visual noise - basically a lot of light and dark marks crammed together generating so much contrast that the viewer’s eye would shoot right to it. It would probably even hurt to look at.
We always have to be in control of our drawing - and specifically, how our drawing leads the viewer’s eye around. As such, focal points must only exist where we intend them to. The trick to achieving this kind of control is to imply the presence of forms. We can do this by leveraging the cast shadows explained above - instead of actually drawing outlines around each of these textural forms, instead of drawing them directly, we capture the shadows they cast on their surroundings.
When people track a particularly elusive animal in the wilderness, they can derive a lot of information from the signs they leave behind. The tracks, their scat, the fur that might get caught on branches and bushes. Without ever seeing the animal itself, they can get a sense of how big it is, what colour, what it’s been eating - that’s essentially what we’re providing the viewer with here. We’re not drawing the forms themselves, we’re not giving them explicit and direct information, but instead we’re giving them enough from which to derive a general understanding of how that form sits along the surface of the object, how big it is, etc.
It’s part of an ongoing course I’m taking, but hopefully it will still be helpful.
