General rule for vanishing: Do all sets of parallel lines that are not parallel to the picture plane vanish (converge) at a point in perspective construction?

Difficulty: Easy

Correct Answer: Correct

Explanation:


Introduction / Context:
The visual hallmark of perspective is that parallel sets not parallel to the picture plane appear to meet at a finite location, called a vanishing point. This principle governs one-, two-, and three-point constructions alike.


Given Data / Assumptions:

  • Picture plane is a vertical plane in many setups, but the rule holds for any PP orientation.
  • Station point defines the viewpoint; rays project 3D directions onto PP.
  • Parallels parallel to PP do not converge; they remain parallel in the image.


Concept / Approach:
For each family of parallel edges not parallel to PP, there exists a unique vanishing point. Construct a ray from the station point parallel to that family; its intersection with the picture plane is the VP. Different directions produce different VPs (for example, two sets of horizontal edges give two VPs on the horizon line in a two-point view).


Step-by-Step Solution:
Identify a family of parallel edges not parallel to PP.From SP, create a direction ray parallel to that family.Intersect that ray with PP to locate the vanishing point.Note that all edges in that family project toward this VP, confirming convergence.


Verification / Alternative check:
Observe buildings at a street corner: two façade directions yield two distinct VPs on the horizon; if the viewer also looks upward, vertical edges converge to a third VP.


Why Other Options Are Wrong:
Limiting the statement to special subjects, centered viewpoints, or object elevations ignores the fundamental geometric rule.


Common Pitfalls:
Forgetting that parallels exactly parallel to PP remain parallel; conflating horizon placement with the existence of VPs.


Final Answer:
Correct

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