1. Establishing locations by a system of overlapping triangles where the angles are directly measured but only a few of the sides are directly measured. Sometimes called the method of intersection. First-order triangulation has an accuracy from one part in 25 000 to one part in 100 000; second-order, an accuracy of one part in 10 000; third-order one in 5000. Fourth-order is ‘‘without any appreciable error’’ considering the application of the survey results. Triangulation with a plane table is shown in Figure P-2 (but a plane table is not an accurate way to triangulate). Compare traverse and trilateration. 2. Tesselation (q.v.), representation of a surface by triangles.