For example: if someone used a lot of paint on their canvas to the point where you can see the visible, bumpy, rough streaks(texture), one could interpret this many ways. They could have been painting it when they were sad or angry(therefore making the viewer feel sympathetic, agitated, or sad). But of course, this depends on the artist's painting style and/or the concept of the work. The more detail(value and texture), the more realistic it most likely will be(or abstract). A variety of texture and value in the work of art could also contribute to realism. If you have anymore questions on this topic, do not hesitate to ask. Hope this helped!
One of the pioneers of this medium, Timothy O'Sullivan, started his career as a Civil War photographer. He toured throughout the Western United States with geological survey parties after the war.
