Foreshortening conditions: Are only vertical lines located behind the picture plane foreshortened, or does foreshortening apply more broadly to lines not parallel to the picture plane?

Introduction / Context:
Foreshortening is the apparent reduction in length of features angled relative to the picture plane. This question tests the misconception that only vertical lines behind the picture plane are foreshortened.

Given Data / Assumptions:

• A line appears in true length only when it is parallel to the picture plane.
• Any line oblique to the picture plane is foreshortened in the image.
• Verticals may or may not foreshorten depending on whether vertical convergence is used (e.g., three-point perspective).

Concept / Approach:
The amount of foreshortening depends on the angle a line makes with the picture plane, not on whether it happens to lie in front of or behind the PP. In one- and two-point perspective with a vertical PP, vertical edges are typically parallel to PP and hence are not foreshortened, whereas receding horizontal edges are. In three-point perspective, verticals also converge and therefore foreshorten. Thus, limiting foreshortening to “vertical lines behind the PP” is incorrect.

Step-by-Step Solution:
Determine if a line is parallel to the PP (true length) or oblique (foreshortened).Recognize that position relative to PP does not by itself govern foreshortening; orientation does.Apply to verticals: in three-point views, they foreshorten; in one-/two-point with vertical PP, they usually do not.Conclude the statement is false.

Verification / Alternative check:
Inspect standard cube diagrams: receding edges shrink while faces parallel to PP maintain true shapes; verticals foreshorten only when vertical convergence is introduced.

Why Other Options Are Wrong:
Restricting foreshortening to one axis or a special crossing of the ground line misunderstands the orientation-based rule.

Common Pitfalls:
Confusing “behind the PP” with “oblique to PP”; assuming verticals are always foreshortened.

Final Answer:
Incorrect