2.6.2. Resection Calculator

2.6.2.1. Overview

The Resection calculator computes the position (X, Y, Z) and orientation of a total-station setup from directions and distances to known control points, using a rigorous iterative least-squares adjustment. It is a faithful re-implementation of the teramon resection: given the same input it reproduces teramon’s adjusted coordinates and its adjustment statistics, so it can be used to re-solve and cross-check a teramon resection.

Unlike the Free Station calculator, this tool accepts raw two-face readings (face I / face II, several rounds per point) and reduces them itself, reads teramon’s own .rs1 / .rs2 / .res files, and solves a separate trigonometric height net so the result is a full three-dimensional position at the instrument centre.

The tool is found under Calculations > Survey Calculator > Resection.

2.6.2.2. Inputs

Settings (top-left editor):

Key

Default

Meaning

Station name

ST

Name of the solved (free) station.

Seed X / Y / Z

0

Approximate station coordinates. A starting position is required — the adjustment is iterative and linearises about this seed (it is read from .rs1 on import).

Instrument height

0.000

Height of the instrument above the setup mark (metres). Read from .rs1.

Sdif

50

Convergence threshold on the change of the cost function between iterations.

SigmaDir

5

Direction standard error (teramon units; 5 = 0.5 mgon).

DeviceA / DeviceB

0.5

Distance error model constants (≈ 5 mm + 0.05 cm/km).

The four numeric settings default to teramon’s own values; leave them as they are to match teramon.

Known points grid — one row per control point (held fixed):

Name · X · Y · Z · Target height · Use

Observations grid — one row per raw pointing:

Target · Set · Face · Hz (gon) · Vz (gon) · Slope dist · UseH · UseV

Rules:

  • All angles are in gon (400-gon circle). Vz is the zenith angle (100 gon is a level sight). There is no DMS input.

  • Observations are raw two-face: enter Face as RI (face I) or RII (face II), and use Set to number the rounds. Several rounds and both faces per target are averaged automatically before the adjustment (face II is folded by ±200 gon in Hz and 400−Vz in the vertical, then meaned).

  • UseH includes the target in the horizontal (position) net; UseV in the vertical (height) net.

  • Target height is a property of the control point (its column in the Known points grid), not of each shot.

  • Decimal comma and decimal point are both accepted.

2.6.2.3. What Compute does

  1. Reduces the raw two-face / multi-round readings to one direction, zenith and slope distance per target.

  2. Horizontal net — an iterative weighted least-squares adjustment with the controls held fixed and the station free, solving X, Y and one orientation unknown from the directions and the derived horizontal distances. This reproduces teramon’s algorithm exactly, including its weighting and convergence rule.

  3. Vertical net — a trigonometric-height adjustment for the station height. The reported Z is the height of the instrument centre (station ground mark height + instrument height); the ground-mark height is Z − instrument height.

2.6.2.4. Results

The results panel reports the solved station X, Y, Z (instrument centre) and orientation, the adjustment statistics for both nets (kritirio, standard deviation, degrees of freedom — the same figures teramon prints), a clean, unit-consistent sigma0 computed alongside (directions in mgon, distances in mm), and the per-target residuals.

  • A WARNING line appears if the adjustment did not converge within the iteration limit (check the geometry and observations).

  • If the solve cannot start, the panel shows a diagnostic — most often a missing station seed or a target that is not in the Known points grid.

The sketch pane shows the controls, the solved station and the sight rays; scroll to zoom, drag to pan.

2.6.2.5. Import / Save / Load

Import teramon… reads teramon’s resection files. Pick the .rs1 (control points, station seed and instrument height); the matching .rs2 (reduced observations) and/or .res (raw two-face field record) with the same base name are read automatically. This fills the grids so the setup can be re-solved. Import is read-only — the calculator does not write teramon files.

Save… / Load… use the calculator’s own tagged-CSV format that round-trips the grids:

STATION,ST,265423.9804,4363955.4316,573.7537,0.24
CTRL,R3,265420.8154,4364009.3436,576.3112,0.000
OBS,R3,1,RI,396.24201,97.26278,54.05766,1,1
OBS,R3,1,RII,196.24251,302.73894,54.05736,1,1
SET,Sdif,50
SET,SigmaDir,5
SET,DeviceA,0.5
SET,DeviceB,0.5

  • STATION,name,X,Y,Z,instrumentHeight

  • CTRL,name,X,Y,Z,targetHeight

  • OBS,target,set,face,Hz,Vz,Slope,useH,useV

  • SET,key,value for each adjustment setting.

2.6.2.6. Notes

  • Coordinates follow the convention X = Easting, Y = Northing, Z = up, metres; angles in gon.

  • The tool reproduces teramon’s figures faithfully, including teramon’s own convention of pooling direction and distance weights in mixed units. The separate clean sigma0 is provided as a unit-consistent quality indicator; it does not change the solved coordinates.

  • The reported Z is at the instrument centre. Subtract the instrument height to get the ground-mark height.