Pick up the incorrect statement from the following: A. In truly vertical photographs without relief angles are true at the plumb point B. In tilted photographs without relief, angles are true at the iso-centre C. In tilled photographs with relief, angles are true at the principal point D. None of these

The correct answer is: C.

In a truly vertical photograph, the plumb point, isocentre, and principal point coincide. However, in a tilted photograph, the plumb point and isocentre are no longer coincident. The isocentre is the point on the photograph where the optical axis of the camera intersects the image plane. The principal point is the intersection of the optical axis and the ground plane.

In a tilted photograph with relief, the angles between the lines of sight to two points on the ground are not true at the principal point. This is because the principal point is not the same as the plumb point. The plumb point is the point on the ground directly below the camera. The angles between the lines of sight to two points on the ground are true at the plumb point.

Therefore, the statement “In tilled photographs with relief, angles are true at the principal point” is incorrect.