﻿ Geometric constructions on a map

# Geometric constructions on a map     At an execution of geometrical constructions on a map the following basic concepts are used:   Basic line (basis of construction) - a starting line, coordinates of initial and terminal point of which are known.   Initial point  of a basic line - a point on a map at which coordinates are known, and together with a terminal point it forms a basic line and from it the measurement of distance and corners from a basic line is made.   Terminal point  of a basic line - a point on a map at which coordinates are known and it together with initial point forms a basic line.   Picket point  - a point of district which coordinates are calculated.   For an execution of geometrical constructions it is necessary to specify a basic line on a map. The choice of a basic line can be carried out by two ways: by the consecutive indication of two point objects (the first point - the initial point, the second point - a terminal point) and a choice of a piece of the metrics of linear or polygon object.     Following variants of construction are possible: - calculate coordinates (direction corner and distance); - calculate coordinates (rotary corner and distance); - calculate coordinates (an angular resection); - calculate coordinates (linear resection); - calculate coordinates (linear resection from three stations); - calculate coordinates (method of normals); - calculate coordinates (method of stvors); - calculate coordinates (crossing of stvors); - create normal on a line.   After a choice of basis of construction the user carries out input in corresponding dialog of the measuring data, necessary for calculation of coordinates of a picket point. In a dialogue of data input there is a figure which evidently explains what information it is necessary to enter for calculations.     Calculations of coordinates of a picket point can be executed to the left and to the right of basis of construction. To set the side for calculations, and as to change a direction of basis of construction (to interchange places the initial and final points) it is possible during input of the information, having set necessary value of corresponding elements of dialog. 