Crivelli wanted to show depth in his picture and he used a simple single-point perspective. 克里维利想要在他的图画中显现出深度，于是他采用单点透视。
After one semester teaching experiment, we proved that Perspective Practice has remarkable effects on improving two point perspective cube sketching ability. 经教学实验后，证明本辅助绘图软体对于两点透视正立方体之绘制能力，具显著成效。
