To determine which technique the artist did not use to create the image illustrating perspective, we can analyze each option:
- Vanishing point - A key element of linear perspective, where parallel lines appear to converge at a single point in the distance.
- Horizon line - This line represents the viewer's eye level and is crucial for establishing perspective in an artwork.
- Orthogonal lines - These are the lines that lead to the vanishing point and help create the illusion of depth in perspective.
- Monochromatic colors - This term refers to the use of a single color or shades of a single color, which is not a technique specifically related to creating perspective.
Based on this analysis, the technique that is not specifically related to creating perspective is Monochromatic colors.