Total Station Not Accurate? 10 Common Causes of Surveying Errors Malaysia

When survey results do not match known coordinates, construction grid lines or previous measurements, it is easy to conclude:

“The total station is not accurate.”

However, the total station itself is only one possible source of error.

Incorrect results can also come from the tripod, tribrach, prism, prism constant, instrument height, prism height, backsight, centering, levelling or field procedure.

Before sending an instrument for repair, it is useful to systematically identify where the problem may be coming from.

Here are 10 common causes of total station surveying errors.

1. Total Station Is Not Properly Centred

The total station should be accurately positioned over the intended survey station.

If the instrument is offset from the control point, the observations are being made from a different physical position.

Centering errors can occur because of:

• Poor tripod positioning

• Optical plummet misalignment

• Laser plummet misalignment

• Tripod movement

• Failure to recheck centering after levelling

A good setup procedure is:

Centre → Level → Recheck Centre → Recheck Level

For precision work, do not skip the final centering check.

2. Total Station Is Not Correctly Levelled

Incorrect levelling is another common source of problems.

Before measurement, check:

• Circular level

• Electronic level

• Levelling screws

• Tripod stability

• Tribrach stability

Do not rely on the compensator to correct a badly levelled instrument.

The compensator is designed to deal with small residual tilt within its specified range, not replace proper setup.

3. Wrong Backsight

A backsight establishes the orientation of the total station.

If the wrong backsight point or coordinates are used, subsequent measurements can be incorrectly oriented.

This can be particularly serious because the total station may continue working normally.

The measurements can look internally consistent while the entire survey orientation is wrong.

Always verify:

• Occupied station

• Backsight point

• Backsight coordinates

• Orientation

• Point identification

before starting large amounts of fieldwork.

4. Wrong Instrument Height

Instrument height is used when calculating elevations and coordinates.

A simple data-entry mistake can therefore produce incorrect results.

For example:

Actual instrument height: 1.520 m
Entered instrument height: 1.250 m

The difference is:

0.270 m

That is a major error for elevation-related work.

Measure the instrument height carefully and confirm the entered value.

5. Wrong Prism Height

Prism height is another frequent field error.

If the prism pole is set at one height but another value is entered into the total station, calculated elevations can be wrong.

This commonly happens when:

• Prism pole height is changed

• Different operators share equipment

• A mini prism is introduced

• The value from a previous setup remains stored

Whenever prism height changes:

Change the physical height → Update the instrument setting

6. Wrong Prism Constant

The prism constant affects EDM distance measurement.

Different prism systems may require different constants.

If the wrong setting is selected, the total station can produce a systematic distance offset.

This is particularly dangerous because the readings may be very repeatable.

The operator may therefore believe the measurements are accurate.

Always check:

Prism Type → Prism Constant → EDM Mode

especially when changing prisms.

7. Prism Pole Is Not Vertical

Even if the total station setup is perfect, the target itself can introduce errors.

If the prism pole is leaning, the prism is no longer positioned directly over the intended ground point.

The resulting position error becomes more significant as the pole height and tilt increase.

Use the pole bubble carefully and maintain the prism pole vertically when measuring important points.

For precision work, the condition and adjustment of the prism-pole bubble should also be considered.

8. Tripod or Tribrach Is Unstable

The total station may be perfectly calibrated but still produce unreliable results if its physical support moves.

Check for:

• Loose tripod joints

• Loose tripod head

• Tripod legs sinking into the ground

• Damaged tribrach

• Loose levelling screws

• Instrument not properly secured

This is particularly important on construction sites where the instrument may be set up on:

• Soft soil

• Loose aggregate

• Wet ground

• Temporary platforms

• Surfaces exposed to vibration

Always consider the complete setup:

Ground → Tripod → Tribrach → Total Station

9. Atmospheric and Environmental Conditions

Long-distance measurements can be affected by environmental conditions.

Factors may include:

• Temperature

• Atmospheric pressure

• Heat shimmer

• Rain

• Fog

• Strong sunlight

• Line of sight close to hot surfaces

In Malaysia, strong daytime heating can create visible atmospheric turbulence over roads, concrete slabs and open construction areas.

For precision measurements, follow the total station manufacturer's procedures regarding atmospheric corrections and operating conditions.

10. Total Station Requires Calibration or Repair

After the setup, prism and field procedure have been checked, the problem may indeed come from the total station.

Possible areas include:

• Horizontal angle measurement

• Vertical angle measurement

• EDM

• Compensator

• Telescope alignment

• Optical or laser plummet

• Levelling system

• Mechanical movement

This becomes more likely when the same abnormal result occurs repeatedly under controlled conditions.

Total Station Accuracy Troubleshooting Checklist

When measurements look wrong, do not immediately change random settings.

Work through the problem systematically:

1. Check control point

↓

2. Check centering

↓

3. Check levelling

↓

4. Check station coordinates

↓

5. Check backsight

↓

6. Check instrument height

↓

7. Check prism height

↓

8. Check prism constant

↓

9. Check EDM/target mode

↓

10. Check tripod and tribrach

↓

11. Repeat measurement

↓

12. Compare with known reference

If the discrepancy remains, consider professional instrument inspection.

How Do I Know Whether the Error Comes From the Total Station or Surveyor?

Try to make the test as controlled as possible.

Use:

• Known control points

• Known reference distance

• Stable tripod

• Correct prism

• Verified prism constant

• Experienced operator

• Repeated observations

If the problem disappears after correcting the setup, the instrument may be functioning normally.

If the same discrepancy continues under controlled conditions, the total station deserves closer investigation.

Why Are My Coordinates Wrong but Distance Looks Correct?

If distance appears reasonable but coordinates are incorrect, investigate setup information such as:

• Station coordinates

• Backsight coordinates

• Orientation

• Instrument height

• Prism height

A coordinate problem does not automatically indicate an EDM problem.

Why Is My Distance Wrong but Angles Look Normal?

Check:

• Prism constant

• Prism type

• EDM mode

• Prism condition

• Atmospheric settings

• Targeting

If these are correct, EDM performance can then be investigated.

Why Are My Elevations Wrong?

Elevation discrepancies may be associated with:

• Instrument height

• Prism height

• Vertical angle

• Poor levelling

• Prism pole tilt

• Incorrect control elevation

• Telescope/vertical angle alignment

Check the simplest field inputs before assuming an internal fault.

Why Does My Total Station Give Different Results Every Time?

Inconsistent results can indicate instability rather than a fixed calibration offset.

Check:

• Tripod movement

• Tribrach looseness

• Prism pole movement

• Poor targeting

• Heat shimmer

• Compensator behaviour

• Mechanical play

Repeatability is an important troubleshooting clue.

Total Station Was Dropped – Can I Continue Using It?

A significant impact should not be judged only by whether the instrument still powers on.

A total station may continue measuring while an internal alignment has changed.

After a significant drop, consider checking:

• Horizontal angle

• Vertical angle

• EDM

• Compensator

• Telescope alignment

• Optical or laser plummet

• Levelling system

For critical construction or control work, inspection before returning the instrument to service is advisable.

Field Check vs Professional Calibration

Field checks are valuable.

They can help identify:

• Setup errors

• Wrong settings

• Repeatability problems

• Obvious measurement discrepancies

But:

Field Check ≠ Formal Calibration

Professional calibration provides a more controlled assessment of instrument measurement performance.

Total Station Accuracy Check & Calibration Malaysia

MTM Precision provides total station inspection, troubleshooting, calibration, servicing and repair in Malaysia.

If your survey team is experiencing:

• Wrong coordinates

• Distance discrepancies

• Angle discrepancies

• Elevation errors

• Compensator errors

• Plummet alignment problems

• Total station repeatedly going out of level

• Problems after a drop or impact

the complete setup can be considered to determine whether the issue comes from the operator settings, prism, tribrach, EDM, angle system, compensator or instrument alignment.

When possible, provide the exact symptom and bring the accessories normally used with the instrument. This can make troubleshooting more effective.

Contact MTM Precision

MTM Precision Sdn. Bhd.
Showroom & Service Centre
No. 29-1 & 29-2, Jalan Bandar 18,
Pusat Bandar Puchong,
47160 Puchong, Selangor, Malaysia

🌐 Website: www.mtmpre.com.my
📧 Email: mtmpre@yahoo.com
📱 WhatsApp: +6016-660 7346