June 12, 2011

    I squinted and stared... It was amazingly difficult to tell exactly what it is that makes the back of a pile of beans visually fall away, or go back down toward the table. Given the small distance involved it's not the usual little tricks like a change in size or sharpness, and it's nothing about the lighting or shadows on the beans or table. 
    To figure it out I had to maximize some of the variables; make the lighting harsh, move it around, increase the height of the pile... Ah! Increasing the height of the pile did it - when the pile is higher there are clearly two factors that affect the way we see it. One is that just at the sharpest part of the change in the far slope, the beans are a bit more foreshortened and/or overlap just a bit more so each one presents a bit less of itself to the eye even though all orientations are present all over the pile, including there... and the other is that on the portion of the pile that's sloping away from you, you no longer see the small dark spaces between the beans - the darkest little triangles and wedges of shadow.
    My difficulty was in part that I had begun with a rather flat "hill of beans" so that the relevant variables weren't readily apparent, and that I had begun with a fairly overhead view which also minimised the usefulness of the visual cues. Since most of the bean shapes were already drawn and I didn't want to mess up the paper enough to erase the ones at the visual horizon, I couldn't entirely put my discovery to good use. For example, the right side of the pile doesn't conform as nicely to "pile" shape as the left side where I could incorporate some of the shape and overlap cues. There was no problem placing the "looking Into the pile" shadows over the entire front. 
    The hindrance of being limited by what I'd previously drawn didn't bother me as much as I might expect since the whole thing still felt like an experiment. I can't say when it will help me out - drawing piles of gravel? I hope not! But perhaps it will, and maybe I've gathered a bit more in the line of practice in looking at things and decoding for myself the mystery of how we see.