Route calibration |
|
|
«Route calibration» mode must be called before using all other modes for calculation based on measurements, otherwise calculations may be performed with errors. For calibration it is necessary to select a linear object - a route on the map and then enter the values required for calibration in the dialog. Two variants of calibration are provided: - by length of a route; - by data from a file. At calibration by «length of a route» numerical values of slope distance and measurement of the entire route are used. For calculation of scale factor the user-entered value of a route measurement and the calculated slope length of the entire route are used. Calculation of M coordinate is made for the entire route by uniform values. In this case the route is presented by the metrics of one object without subobjects. At calibration by «data from a file», you can use different scale factors for individual sections of the route. Calibration by «by data from a file» is intended for use at measurement of distances on roads with a binding to kilometre signs. As a rule, the distances between kilometer posts can differ significantly from the value of 1 km (both up and down). On such route different scale factors for each kilometer of road are used. The calculation of the M coordinate is performed with preliminary segmentation of the route and the calculation of different values of the scale factor. For calibration a CSV file containing information about measurements of kilometer posts is used: SXYHМ, where S - the serial number of the kilometer post. X - the value of the X coordinate of the kilometer post Y - the value of the Y coordinate of the kilometer post H - the value of the H coordinate of the kilometer post M - measurement of the length of the segment between kilometer posts. In the file, one line corresponds to the description of each kilometer of the road, starting from 1 (one). The measurement of the 0th kilometer is 0 (zero) and is not included in the file. The route slope length (DH) and the route measurement value (M) are used to calculate the M coordinate. The slope length of the route is calculated taking into account the coordinate H, is equal to the sum of the slope lengths of the segments between the kilometer posts and is calculated by the formula: j<=J DH = Ʃ sqrt (Dj2 * ΔHj2) j=1 j - number of the current segment of the route metric (section) J - number of route metric segments (sections) Dj - length of the metric segment of the current point in the map projection ΔHj - a difference of points heights of a current segment of the metric Information about the heights (H) of the route points can be obtained in advance from the matrix of heights of the relief. If there is no height, the slope length is equal to the length calculated in the map projection (DH = D). A single value of measurement of a route length (M) is entered by the user. The measurement values of route kilometers (M) are obtained from the file. To correct the difference in DH and M values, the scale factor (K) is calculated, a parameter used in calculating the spatial position of the picket. The scale factor is calculated using the formula: K = M/ DH M – measured length of a route DH – slope length of a route
Calibration by file is intended for calibration of autoroads and the railways by information about the distances between kilometer pickets. In a file the all pickets located on a route from the first to the last point should be described. The route must be represented by an object without subobjects. If the number of route subobjects does not match the number of kilometer pickets, the calibration is not performed. When calibrating by a file, a checking onto a topological consistency of kilometer pickets and a route line is additionally carried out. If points are outside a route line on distance of more the tolerance, calibration is not carried out.
|
Calibration is the process of calculating the M coordinate for 