This sketch brushwork exercise—not, this small grid filled with Gu Weijing's personal creativity, in Professor Walter's eyes, has already departed from the realm of practice and can be considered a simple geometric sketch.
The sketch itself, although not bad, hasn't reached the level deserving of such astonishment from Professor Walter.
Honestly speaking,
it's merely a top-down view of a pyramid with a lighting effect.
Sketching geometric plaster models, cones, spheres, and even various crooked asymmetric figures are basic skills for art students learning sketching.
The base is a square pyramid without curved surfaces, so the light and shadow changes are not complex.
Any Fitz sixth or seventh-grade art student could draw such a shadowless top-down view.
What truly made waves of shock surge in Professor Walter's heart, wanting to swallow his tongue was...
He could tell that this entire sketch was drawn by Gu Weijing using an ordinary 2B pencil!
