Tacheometric survey calculator: field book reduction, contour plan and 3D terrain

Enter the station data and the readings to staff points — the calculator computes horizontal distances, height differences, elevations and coordinates, draws a contour plan and a 3D terrain model.

H of station, mi (instrument height), mContour interval, mX of stationY of stationα₀ (to the reference, circle at 0°)Distance DVertical circleМО (index error, for face-left readings)

Field book: staff points

№	№	β (horiz. circle)	D, m	ν or FL	v, m (empty = i)
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You can paste a block from Excel or Word: click a cell and press Ctrl+V.

Angles in degrees and minutes: 12°30′, 12 30, −0°40′. The table can be pasted from Excel. Leave v empty if you sighted at instrument height. The circle reads 0° on the reference point with bearing α₀.

Calculate

Reducing a tacheometric field book

ν = FL − IE; stadia: d = D·cos²ν, h′ = ½·D·sin 2ν; slope distance: d = D·cos ν, h′ = D·sin ν; h = h′ + i − v; H = H_st + h; X = X_st + d·cos α, Y = Y_st + d·sin α.

Contours are drawn by triangulating the points and interpolating linearly along triangle sides.

FAQ

How is the horizontal distance computed?

Stadia: d = D·cos²ν; total station slope distance: d = D·cos ν.

How is the spot height found?

H = H_st + h′ + i − v.

What is the index error?

The vertical circle reading for a horizontal line of sight; ν = FL − IE.

How are contours drawn from spot heights?

Triangulate the points, interpolate the contour levels along triangle sides and join them.

Which contour interval?

Usually 0.5 or 1 m for 1:500–1:1000 plans, 0.25–0.5 m for flat terrain.