Give the number of principal vanishing point(s) along with their direction for…
2015
Give the number of principal vanishing point(s) along with their direction for the standard prospective transformation :
Answer: A. Only one in the direction K — Answer: There is one principal vanishing point, in the direction K (the viewing/optical axis). Explanation: Standard perspective setup: the image plane is…
- A.
Only one in the direction K
- B.
Two in the directions i and j
- C.
Three in the directions I, J and K
- D.
Only two in the directions J and K
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Correct answer: A
Answer: There is one principal vanishing point, in the direction K (the viewing/optical axis).
Explanation:
Standard perspective setup: the image plane is perpendicular to the viewing axis (K) and contains the i and j directions.
Lines parallel to directions that lie in the image plane (i and j) remain parallel after projection, so their vanishing points are at infinity and do not appear as finite points on the image.
Lines parallel to the viewing axis K intersect the image plane at a common finite point: the principal vanishing point (often coinciding with the image center).
Therefore, in this standard perspective configuration, only one finite principal vanishing point exists, along K.
Key takeaway: only the viewing axis (K) produces a finite principal vanishing point; directions lying in the image plane do not.