START First steps Deutsch Guide : Measurement lists

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General structure of a measurement record Measurement lists for Traverses and Universal computer Measurement lists for Sets of angles and distances and Station centring Measurement lists for Vertical networks and Trilateration and multilateration Quantities in the station rows may be: Quantities in the target rows may be: Quantities for network lines may be: Units Measurement lists with distances etc. in grid scale Missing measurements
Measurement lists are lists of measurement records, a special kind of tabular data records. Measurements are various types angles, distances, height (differences) and much more.

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At the moment measurement lists are used by the following computation tools:




START First steps Deutsch General structure of a measurement record

In each non-empty row of a coordinate list one measurement set is defined. Each row consists of one up to seven fields separated by semicolon or white space (column separator):

Blank rows as well as pure comment rows are ignored.

START First steps Deutsch Measurement lists for Traverses and Universal computer

(see / / / )

The succession of stations in a measurement list and the succession of target rows belonging to one station is arbitrary. This is true even for .

On each point there may be multiple station setups, such that this point recurs in station rows. However, for only the first station setup is used, which is indicated by a warning.

Each target point can be measured at a station multiple times, usually in the case of so-called . In this case it is recommended to process each station setup separately by , where in conjuction with the determination of instrument errors, set means and standard deviations are computed. Otherwise only simple means are computed.

START First steps Deutsch Measurement lists for Sets of angles and distances and Station centring

(see / / / )

are in principle built as described in the preceding section, but consist only of target rows, all belonging to the same station. There is only one station. The succession of all rows is arbitrary.

START First steps Deutsch Measurement lists for Vertical networks and Trilateration and multilateration

(see / / / )

Each data record contains the data belonging to one network line followed by up to five measurements and/or accuracy measures. All rows start with two pointnames: startpoint and endpoint of the network line. The succession of all rows is arbitrary.

START First steps Deutsch Quantities in the station rows may be:

orientation angle o
specifies the ⇓ azimuth of the horizontal circle scale index of the station.
instrument height ih
specifies the height of the tacheometer tilting axis above the station marking (usually zero, if the station point is not marked)
default target height th
replaces all missing target heights in this measurement list (default value)

START First steps Deutsch Quantities in the target rows may be:

Coordinates and
polar measurements
Coordinates and polar measurements
horizontal angle r
is the angle between the horizontal circle scale index of the station and the target, measured in the horizontal plane of the station (horizontal angle). If the associated zenith angle is missing then the face 1 is assumed.
azimuth t
is the horizontal angle between grid north and the target
horizontal distance e or slope distance s
horizontaler oder schräger Abstand von Stand- und Zielpunkt oder Anfangs- und Endpunkt
zenith angle v
is the angle between the zenith and the target. Elevation angles are not supported yet.
target height th
specified the height of the reflexion point or targeted point above the target marking (usually zero, if the station point is not marked)
height difference dh
specifies the height of the reflexion point or targeted point above the tacheometer tilting axis (negative if the tilting axis is higher)

Angles are oriented from the X or north axis to the Y or east axis, this is for the lefthanded system, seen from above, clockwise (⇑ figure).

START First steps Deutsch Quantities for network lines may be:

nivellierte
Netzlinie AE
levelled network line

specific for spirit levelling networks

Height difference dh (required)
is the difference between endpoint and startpoint height of a line. If from startpoint to endpoint it goes uphill, height differences are specified positive, otherwise negative or zero.
Length of levelling line l (optional)
specifies the approximate length of a levelling line and may be used to define weights. The values must not be negative.
trigonometrische
Netzlinie AE
trigonometric network line AE

specific for trigonometric vertical networks

Zenith angle v
Horizontal distance e or slope distance s
Instrument height ih
Target height th
have the same meaning as in the station and target rows.

All values are always required. Missing values ih, th are padded by the default values, if any.

for both kinds of vertical networks

Standard deviation (a priori) σdh or weight pdh of the height difference
are used in the adjustment for the stochastic model. Only one of both values can be present. A default value pads all missing values in this column, or all values. Otherwise a missing accuracy measure is treated as zero standard deviation or infinite weight, which means that in the adjustment the related height difference acts as a constraint.
Also for trigonometric vertical networks these values refer to the adjustable height difference dh = s·cot(v) + ih - th, i.e. they include measurement errors in the instrument height and target height.
Code (optional)
is currently ignored.

specific for trilateration and multilateration networks

horizontal distance e or slope distance s
have the same meaning as in the station and target rows.
Standard deviation (a priori) σe or σs or weight pe or ps of the height difference
are used in the adjustment for the stochastic model. Only one kind of accuracy measure can be present. A default value pads all missing values in this column, or all values. If accuracies are entirely missing, all weights are set to unity, while a warning is issued.

START First steps Deutsch Units

All angular quantities o, r, t, v are expected in the specified angle unit.

All other quantites e, s, dh, l, ih, th are always expected in the natural length unit , i.e. in case of a grid system the grid scale must not be applied beforehand.
ExceptionLengths of levelling lines l may have a different unit of length, i.e. it may be kilometres, while the other quantities are specified in metres. Moreover, a grid scale can be neglected here.

START First steps Deutsch Measurement lists with distances etc. in grid scale

In the unit for metric quantities e, s, dh, l, ih, th must always be the natural length unit .

If for the grid system in a measurement list the grid scale is always applied nonetheless, please temporarily change the system type to cartesian (XYZ or YXZ) lefthanded and perform the computations. Now everything is computed in the grid scale. Afterwards reset the system type back to grid system (northing easting height or easting northing height).

By the way, the same trick works for translation parameters as well as for edge lengths and lattice spacings for Create lattice points.

START First steps Deutsch Missing measurements

Measurement values can be missing in any way, in the all measurements can be missing and only pointnames are given. Blind targets. If a value in missing inside the row, the ;; notation can be used, exemplary in Cylinder through seven points.

Missing measurements are always treated as unknown, also instrument and target heights! Here and there a default value may be given.

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