Abstract
In order to adjust a trilateration net, we used to apply the method by observation equations more frequently compared with the method by condition equations. The main reason is that the more complex a trilateration net is, the more difficult the formation of condition equations is. It is evident that finding and describing the condition equations which are necessary and sufficient for a given problem are not easy. But it is also true that the adjustment by condition equations has some merits described as follows. A gross error or a mistake can be found out by checking an error of closure in a condition equation at an early stage. The number of normal equations to be solved is generally small, and so the adjustment computation is carried out by a personal computer. The purposes of this paper are as follows. 1. To propose a method which will enable us to describe the condition equations by the use of simple rules for applying the adjustment by condition equations to complicated trilateration nets. 2. To describe linearized formulae of the condition equations. 3. To show a systematic computation work for obtaining cofactor (or variance-covariance) matrices of angles, directions of sides and coordinates of stations. 4. To show the characteristics of errors in several typical trilateration chains by investigating the cofactors (or variances). 5. To present some useful data for making a plan of the observation for practical trilateration chains.
