Which of the following is not true in case of Oblique Projections ?

Conclusion: The statement "Projectors are always perpendicular to the plane of projection." is not true for oblique projections.

Explanation: Oblique projection is a form of parallel projection where the projection rays are parallel to each other but strike the projection plane at an oblique (slanted) angle. Only in orthographic (true) projections are the projectors perpendicular to the projection plane.

• Parallel projection rays are not perpendicular to the viewing plane. — This is true: oblique projectors are inclined to the projection plane.

• Parallel lines in space appear parallel on the final projected image. — This is true: parallelism is preserved in parallel projections because rays do not converge.

• Used exclusively for pictorial purposes rather than formal working drawings. — This is effectively true: oblique projections are primarily used for pictorial/illustrative views because depth is not represented to scale, so they are not commonly used for precise engineering working drawings.

• Projectors are always perpendicular to the plane of projection. — This is false for oblique projection: projectors are parallel but oblique. Perpendicular projectors describe orthographic projection.

Notes: Common oblique variants include cavalier (full depth scale) and cabinet (half depth scale) projections, both of which use parallel oblique projectors to give a quick pictorial view.