>>5756909You're right that cast shadows can show the form of the object casting the shadow and the object that is being cast onto. Will weston advices to use them selectively to enhance this like pic related.
I think Hale is saying to ignore any shadow that will confuse the viewer and destroy the illusion of depth.
For example in your image the hair and earring might not necessarily be "good" cast shadows because they are more abstract shapes so they might just flatten the form if you draw them faithfully.
But the shadows on the beach towel help establish a ground plane and place the figure on it.
When working from reference you are always trying to redesign the lighting so that it works for you instead of being a slave to whatever happened to be captured. Think of movies, even when they shoot outdoors they are constantly using artificial lighting and bounce sheets to design the lighting the want instead of whatever lighting happens to be available naturally.
That's why instructors generally teach a simple lighting setup with a 45 degree light, highlight, halftone, core shadow, tone(bounce light), and cast shadow. If you simplify your values into something like this you can make decisions while using reference to redesign the light you see. You can make sure there isn't too little or too much contrast. It's one of these 5 or it doesn't exist in your drawing, there's no cofnusion.
