To determine where values change when light moves over an uneven surface by using a range of values to paint the different values in a realistic, monochromatic self-portrait;
To effectively communicate an image that looks like you through careful examination of the values and structure of your face.
Some skills that I think are necessary are being able to make proportions look accurate/realistic. When you’re mapping out different features if they don’t look accurate or if they’re disproportionate that the self-portrait isn’t really going to look like you. Also being able to use values to show the difference between different facial features and making it look 3d as well. If you use the same value everywhere or if the values are super similar everywhere then the whole thing is going to look flat. Using a variety of values is important so that it’s easier to see where everything is and so that it looks more three-dimensional.