Calculating bulks of earth works

The task: Calculating bulks of earth works is intended for definition of bulks of the earth masses which are a subject to moving within the limits of a local site of district. In the task the calculation by two methods is stipulated: by work points and by discretes of a matrix.

Initial data:

- a matrix of a source relief (a topographical surface);

- a matrix of a project relief (a project surface);

- parameters of building (input of value of a step of the plan grid, a choice of a variant of calculation - by work points, by discretes of a matrix or at once both variants).

Result data:

- a result user map with the plan of works created on the map and with the calculated bulks by a grid of squares;

- numerical values of the calculated bulks which are deduced into corresponding fields of a dialog box.

Before a call of the task the vector map with added to it at least of two matrixes of heights should be opened.

Names of entrance matrixes of heights should differ, otherwise the warning will be given out and calculation will be inaccessible. If matrixes have no zone of superposition the corresponding message will be given out and calculation will not be made.

At the specifying a name of a result user map the check on presence in the specified place on a disk of a map with such name is carried out. If such map already is, the message will be given out, offering to change a name of a result map.

After specifying a step of a grid it will be corrected in view of multiple in relation to the minimal element of one of entrance matrixes, into greater party. For example, if the element of one of matrixes is equal to 25 meters at the specifying a step of 40 meters it will be corrected up to value of 50 meters.

The plan of earth works represents the drawing in the form of a grid of squares with the size of the side specified by user. The less side of a square, the higher the accuracy of calculation. In corners of each square the titles (project points, points of landscape relief and work points) are placed.

In dialog of the task the types of lines for a border, for grid and for lines of zero works are separately set up. Also types of titles for each position are set up and what title into what position to deduce. By default the following values are installed: for A position - the Work point, for B position - the Project point, for C - the Landscape point and for D -  Bulk of earth masses. In dialog the opportunity of a choice of visibility of each of positions is stipulated. All data about lines and titles are chosen from the classifier of the open vector map.

Between corners of squares with work points of different signs the points coordinates of  zero work are calculated. After junction of points of zero works the line of zero works is created.

Depending on presence on the square's sides of points of zero works 2 types of squares distinguish:

- homogeneous, when for all corners the signs of work points coincide, and on all square should be executed either an embankment, or  hollow. The calculated bulk is deduced into the center of a square;

- heterogeneous, when signs of work points at various tops do not coincide also a square is shared by a line of zero works onto sites of  hollow and an embankment. The calculated volumes are deduced into the centers of sites.

If in one of tops of a square even in one of matrixes the height is not certain, the squares adjoining this top are not processed.

The calculated bulks (bulk of positive values, bulk of negative values, the arithmetic sum and the absolute sum) are deduced into corresponding fields of a dialog box of the task.

At calculation of bulks by work points for a homogeneous square the bulk of earth masses V0 is determined as volume of the prism having the area of basis P, equal to the area of a square, and the height equal to an average arithmetic from work points h of all four corners

                         V0 = P * (h1+h2+h3+h4)/4.

Bulks of earth masses in heterogeneous squares are determined after division by their line of zero works and by auxiliary lines (on the plan are not shown) onto separate figures - rectangular triangles, rectangles, trapezes, etc. Bulk of works Vr in separate figures is calculated by the formula

                           Vr = Pr*hср,

where Pr - the area of a separate figure; hср - an average work point of this figure.

At calculation of bulks by discretes of a matrix the surface (matrix) of qualities containing a difference of a project matrix and a matrix of landscape at first is built, with step equal to half of minimal step of one of entrance matrixes of heights. Then bulks of each element of a matrix of the qualities belonging the given square are calculated by formula Velem = h * Pelem, where h - value of a matrix of qualities.

At a choice simultaneously of two variants of calculation the calculated values are deduced on a map one above another: from above by work points, under it in brackets - by discretes of a matrix

In a heterogeneous square with two zero lines (it is divided into three parts) the value calculated by discretes of a matrix, is deduced the common value for two parts with an identical sign into the left top part of a square.