Two-point problem and three -point problem are method of

Explanation:

Two-point problems and three-point problems are methods of orientation & resection.

Resection is a method of plane table surveying in which the location of a plane table is unknown. The location of a plane table is determined by looking at it to known points. 

orientation is the operation of turning the table so that all the lines on the paper are parallel to the corresponding lines on the ground.

Location can be determined through:

1. Two points problems:

• Location of the position on the plan, of the station occupied by the plane table by means of observations to two well-defined points whose positions have been previously plotted on the plan.

2. Three points problems:

• Location of the position on the plan, of the station occupied by the plane table by means of observations to three well-defined points whose positions have been previously plotted on the plan.
• Requires less time, labor and more accurate and simpler.

Important Points

1. For plane table surveying, Levelling is performed first, followed by centering and then orientation.

2. For dumpy level, theodolite, and other instruments, centering is done first.