Surveying is the art of determining relative positions of points on, above or beneath surface of earth. To prepare plan or map is the main object of the surveying.
The primary divisions of the survey are
| PLANE SURVEYING | GEODETIC SURVEYING |
| Surface of the earth is considered as plane. The triangle connecting between three points in earth surface is a plane triangle. Survey accuracy is low. All level lines are straight All plumb lines are parallel. Uses normal instruments like chain, measuring tape, theodolite etc. Carried out for area less than 250 sq.km. | Curvature of the earth is considered. The triangle connecting between three points in earth surface is a spherical triangle. Survey accuracy is high. The line connecting between two points in the earth surface is a curved line. Uses more precise instruments and modern technology like GPS. Carried out for area greater than 250 sq.km. Also known as Trigonometrical survey. Conducted by Survey of India Department. The measurements should be done parallel to the curvature of the earth. |