5 Basics to Avoid Misreading a Total Station's Display

A total station is a surveying instrument that not only measures distance and angle but is used while checking many pieces of information on the screen, such as the instrument station, backsight point, coordinates, elevation, mirror height, measurement mode, and correction conditions.

On site, there are many situations where one moves to the next survey point in a short time, and if measurements are continued without adequately checking the display, this can lead to entering wrong input values, misunderstanding the measurement mode, mixing up coordinate systems, or misreading recorded data.

In this article, we explain five fundamentals that practitioners should understand to avoid misreading screen displays on total stations. Rather than listing model-specific operation names, the content is organized into concepts that are commonly easy to check in the field. It can also be used for daily pre-work checks, in-house training, site handovers, and reviewing survey data.

Table of Contents

• What happens if you misread the screen display of an electronic distance meter?

• Basic 1 Always confirm the measurement mode shown on the display

• Do not confuse the display of the two basic coordinate values with the height.

• Basic 3: Review the input/display of mirror height, instrument height, and correction value

• Standardize the reading of the four basic units, symbols, and decimal points

• Basic 5: Cross-check the measurement point names and observation results before and after saving

• Workplace rules to reduce misreading of on-screen displays

• Summary

What Happens If You Misread an Optical Distance Meter's Display

In work with a total station, it is important that the survey point seen on site, the survey point on the drawing, and the survey point displayed on the instrument screen all match. In actual operations, the instrument is set up, known points and backsight points are established, the mirror is sighted for measurement, and the results are recorded. Throughout this sequence, the screen display provides the operator with important information for making judgments.

If the screen display is misread, the measurement itself may appear to have been completed, yet the resulting data can be difficult to use as deliverables. For example, if you work without confirming the measurement mode, you might think you are performing a coordinate measurement when you have only checked distances, or you might think you are looking at the stakeout guidance screen when you are actually viewing a simple observation-results screen. Because numerical values are displayed on the screen, it can easily give the impression that measurements were taken correctly, which is a point to be careful about.

Also, misreading the display of coordinates or elevations can affect site staking and as-built verification. A horizontal position offset may be relatively easy to notice in some cases, but an elevation mix-up can be discovered only in later processes. In particular, for tasks related to design elevation, existing elevation, elevation difference, and judgments about cut and fill volumes, it is important not to read only the numbers without first confirming what the on-screen display actually represents.

Furthermore, mistakes in entering prism height or instrument height can affect all measurements. If you become complacent just because a number is present in the input field, you may not notice that yesterday’s settings or settings from another site remain. Total stations, convenient as they are, can retain previous settings, so without the habit of checking the display you may confuse the instrument’s proper operation with the correctness of the working conditions.

Misreading screen displays is not something that occurs only because of a lack of experience. In real work there are conditions that make it easy for anyone to skip checks: busy job sites, screens hard to see due to backlighting, operating while wearing gloves, hurried tasks after rain, and shift work involving multiple people. Therefore, instead of trying to prevent misreads by relying solely on individual attentiveness, it is important to decide in advance where on the screen to look, in what order to verify items, and at what points to say them out loud.

Basic 1 Always confirm the measurement mode being displayed

The first thing to check on a total station's screen is which measurement mode you are currently working in. The names shown vary by instrument and settings—distance measurement, angle measurement, coordinate measurement, stakeout, resection, radial observation, check survey, etc.—but the important thing is that the operator understands what the current screen is for.

On site, the screen the previous worker was using may still be left displayed. For example, even if the last time they were checking reference points and this time you intended to set out positions, if you press the measurement button without closely checking the screen, you may acquire data different from your intended purpose. It's easy to feel reassured when measurement values appear, but the numbers shown on the screen are not necessarily directly connected to the intended results.

To prevent misreading the measurement mode, make it a habit at the start of work to check the top of the screen, the menu names, and the item names on the measurement screen. For coordinate measurements, verify how the point name, horizontal distance, vertical angle, coordinate values, and elevation are displayed. For stakeout, understand how the lateral, longitudinal, and vertical differences relative to the design point are indicated. For angle checks, distinguish whether only the horizontal and vertical angles are displayed or whether distances and coordinate calculations are also reflected.

What you should pay particular attention to is the difference between verification tasks and recording tasks. On site, tasks that are merely meant to check a distance coexist with tasks intended to be formally retained as observation data. If you mistakenly treat a value measured only for checking as formal data, or conversely believe you have officially saved data when it was only a temporary display, you'll run into problems later when preparing reports or organizing as-built records. It is important to confirm things such as a display indicating that the data has been saved, the update of the measurement point number, and the reflection in the list of completed observations.

Also, when switching between non-prism measurements and measurements using a mirror, checking the on-screen display is indispensable. Because measurement stability changes depending on reflection conditions and the condition of the target, confirm on the screen that the intended measurement method is selected. If the measurement method is wrong, distance values may become unstable or you may end up measuring a different surface than the point you intended. Which method is appropriate depends on site conditions, so as a basic practice check the measurement mode shown on the screen together with the actual aiming target.

Measurement mode is one item that experienced users are especially likely to overlook. If you assume you are performing the same task every time, you become less likely to notice changes on the screen. Even briefly confirming before starting work “what mode am I in now?”, “what values will be saved from this screen?”, and “what will the next operation execute?” can reduce misreads. The screen display of an electro-optical total station should be treated not as a mere display of results but as an important confirmation area indicating the work state.

Basic 2: Do not confuse coordinate values and elevation display

Multiple numerical values related to coordinates and elevation may be displayed on the screen of a total station. Typical examples include coordinates corresponding to the east–west and north–south directions, elevation, the vertical difference as seen from the instrument, the difference from the design point, and heights that reflect the prism height. All of these are numbers related to position and elevation, but they do not have the same meaning.

Misreadings are prone to occur when multiple numerical values are displayed on the screen. For example, if you interpret the plan coordinate display and the elevation display in the same way, you might mistake which height needs to be checked on site. Also, you may think you are looking at the difference from the design values, but actually read the measured coordinates themselves. Don’t judge solely by whether the numbers are large or small; you need to verify what each field represents.

Coordinate values are displayed based on the coordinate system that is configured. Sometimes public coordinates are used, and other times site-specific local coordinates are used. Which one is correct depends on the project and drawing conditions, but mixing them can lead to major rework. It is important to confirm that the coordinates displayed on the screen match the coordinate system to be used for this site. In particular, when handling multiple site datasets on the same device or when recalling past data to work from, always review the name of the currently open working dataset and its coordinate settings.

When displaying heights, it is necessary to clearly distinguish between elevation and height differences. Elevation is a value based on a reference height system, whereas height differences may be shown as relative differences from an instrument point or a sighting point. Just because a numerical value related to height is displayed on the screen does not necessarily mean it represents the finished height to be used in construction. For each task, confirm what you are looking at—such as the difference from the design height, the existing height, or calculation results that reflect mirror height.

When positioning with an optical surveying instrument, guidance values for lateral and longitudinal directions and the height difference may be displayed at the same time. At that time, it is important to understand whether the on-screen indications are from the worker’s point of view, from the instrument’s perspective, or relative to the design line. Even if arrows or symbols are shown, misunderstanding their meaning can cause movement in the opposite direction on site. In particular, when the field worker and the instrument operator are separated, you need to share the reference for direction before simply converting the display into verbal instructions.

To avoid confusing coordinate values with elevation, it is effective to compare not only the on-screen item names but also the purpose of the task. Decide in advance whether what you want to check now is the horizontal position, the elevation, the difference from the design, or the consistency with reference points; then, when you look at the screen, you will be less likely to be drawn in by irrelevant numbers. Because total stations can display a large amount of information, don’t try to judge all the numbers at once—narrow the fields you view according to your purpose to help prevent misreading.

Basic 3 Review the input and display of mirror height, instrument height, and correction values

On a total station’s screen display, two items that have a significant practical impact are mirror height and instrument height. Mirror height relates to the height of the prism or reflector being measured, while instrument height relates to the height of the total station set up over the instrument point. Because both are involved in height calculations, entering incorrect values will affect the measurement results.

Misreading the mirror height is a relatively common mistake on site. A worker holding the mirror may have adjusted its height, yet the instrument’s input remains set to the previous value. Also, when using multiple mirror poles or when changing the type of mirror during work, you must verify that the mirror height displayed on the screen matches the actual height. Having a number shown on the screen and that number matching the current site condition are two different things.

The same applies to instrument height. When the instrument is repositioned or the tripod height is changed, the instrument height must be rechecked. Because entering the instrument height appears to be a one-time task, it is easy to forget to confirm the entry after repositioning. In particular, when moving from the previous instrument point and continuing work, check that the instrument point information and the instrument height displayed on the screen match the current setup. The more hurried the work on site, the more important it is to fix the sequence of setup, centering/leveling, backsight, and instrument height check as a single routine.

The display of correction values must not be overlooked. On total stations, correction settings for working conditions—such as meteorological conditions, distance corrections, scale factors, and reflection conditions—may be used. You do not pay attention to fine corrections for every job, but for public surveys or tasks that require strict precision control, you need to verify that the setting values match the working conditions. If there are correction-related indicators on the screen, check whether previous settings or settings from another site remain.

However, correction values are not something that field personnel can unilaterally decide to change. Because their handling depends on the survey plan, the client’s specifications, internal company standards, and the intended use of the delivered results, rules should be established in advance when necessary. The important thing is not to proceed with measurements without first checking the correction values displayed on the screen. Even before deciding whether to change them, understanding which settings are currently being used is the first step to preventing misinterpretation.

Mirror height, instrument height, and correction values may appear as small numbers on the screen display. However, they significantly affect surveying results. If an operator looks only at the measurement results shown in the center of the screen and overlooks the settings displayed around them, discrepancies that are difficult to trace later can occur. Check the settings before measurement; if you change conditions during measurement, recheck them; and record them after measurement. By thoroughly following this sequence, you can prevent not only misreading the screen display but also forgetting to apply settings.

Basic 4 Standardize how to read units, signs, and decimal points

On the display of an electro-optical surveying instrument, it is also important to standardize how units, signs, and decimal points are read. Distance, angle, coordinates, elevation, and differential values can be interpreted differently depending on the display units and number of digits. Even if the numerical values themselves are correct, misinterpreting the meaning of units or signs can lead to incorrect on-site judgments.

In distance displays, confirm whether values are shown in meters (m / ft) or whether the differences should be treated in millimeters (mm / in). When reading distances displayed on a screen with decimal points, if you do not decide which digit(s) will be used for on-site judgments, different workers will interpret them differently. When confirming construction positions, it is important to make decisions that match the site’s tolerance range and the purpose of the work rather than focusing on unnecessarily fine digits. On the other hand, underestimating the significance of digits can allow small misreadings to accumulate and lead to positional misalignment.

When displaying angles, pay attention to the distinction between horizontal and vertical angles, the angle units, and the display format. Operators who are not familiar with reading angles may confuse degrees-minutes-seconds displays with decimal displays, causing misunderstandings when confirming directions. If an angle is shown on the total station's screen, verify whether the value indicates the current sighting direction, an angle referenced to the backsight direction, or the difference from the design direction. Because angles can be difficult to relate to the on-site sense of direction, do not judge based on the screen alone; cross-check with the reference direction.

Misreading signs is a problem that frequently occurs in the field. There are many items on the screen that display a plus or minus—left/right, front/back, elevation differences, cut and fill, differences from design values, and so on. The issue is what those signs are referenced to. Whether “right” means right from the operator’s viewpoint or right from the instrument’s viewpoint, or whether it means outside or inside relative to the design line, the same sign can lead to different actions on site. It is dangerous to simply decide “raise because it’s plus” or “lower because it’s minus” without confirming the meaning of the sign.

Be careful not to misread decimal points. On site, displays can become hard to see due to rain, dust, reflections, screen dirt, scratches on protective films, and so on. Overlooking a decimal point can lead to a major misjudgment of a number’s magnitude. Similar-digit misreads can also occur. When recording values by hand, don’t just glance at the screen once; combining a readout with a repeat-back is safer. In particular, when handwriting station names, coordinate values, heights, differences, and the like, confirm that the person who read them aloud and the person who recorded them understand them in the same way.

To unify how units, signs, and decimal points are read, it is effective to decide on the expressions to be used on site. For example, when conveying vertical differences, avoid mixing terms such as "raise," "lower," "higher than design," and "lower than design." For left-right directions, also clarify whether they are from the instrument's perspective or the worker's. Even if the display on an optical surveying instrument is correct, the meaning can shift the moment it is put into words. It is important to align the rules for reading displays with the rules for communicating on site.

Basic 5 Cross-check measurement point names and observation results before and after saving

To use data measured with an optical total station in downstream processes, checks before and after saving are indispensable. To avoid misreading the display, you need to confirm not only the measured values but also the point name, point number, observation type, and the work data where it will be saved. Even if the measurement results are correct, if the point name is wrong, you will run into confusion when organizing the data later.

Misreading point names is a common error at sites where many similar names are used. For example, if reference points, auxiliary points, temporary points, as-built verification points, and batter board points are managed under similar names, it is easy to overlook a difference of a few characters on the screen. Even when managed by sequential numbering, if numbers are skipped or additional points are inserted, the name of the point you are currently measuring can easily become misaligned with the name that gets saved. It is important to cross-check the point name displayed on the screen with the drawings, coordinate lists, and on-site landmarks before measuring.

Before saving, confirm which measurement point the data about to be saved belongs to. After saving, check whether the point name has been updated, whether it is reflected in the list of observed points, and whether the required measurement values remain. Even if you think you pressed the Save button, you may be stuck on a confirmation screen or the data may have only been measured and not saved. Move on only after confirming that the screen shows a save-completed message, that the item has been added to the list, or that the display has advanced to the next measurement point.

When checking observed results, it is important to verify on the spot that the numerical values are not extremely wrong. If coordinate values fall far outside the expected range, distances do not match the on-site sense, a height is unnatural compared to surrounding points, or left-right differences are reversed from what was expected, investigate the cause immediately even after saving. Reviewing everything later makes it difficult to determine when something occurred. The moment the results appear on the total station’s screen is the earliest time to notice an anomaly.

Also, when working with multiple people, it is effective to verbally confirm measurement point names between the instrument operator and the mirror operator. The instrument operator reads aloud the measurement point name displayed on the instrument screen, and the mirror operator checks the on-site point name and location and responds, which reduces misidentification of measurement points. In particular, at sites where similar stakes or marks are lined up, it is important not to assume that the point you are looking at is the correct one. Cross-reference the screen display, the on-site marking, and the names on the drawings.

The save location for work data is also easy to overlook. When using the same total station for multiple sites or on multiple days, saving to a different work file can make the data hard to find later. Check the work name or job name shown on the screen, the date, and the work area, and confirm that the current survey results are being saved to the correct location. Verifying before and after saving may seem like a hassle, but considering downstream tasks such as data organization, report creation, and construction verification, spending a few seconds on site to check is well worth it.

Workplace Rules to Reduce Misreading of Screen Displays

To avoid misreading the screen display of an optical surveying instrument, a system that does not rely too heavily on individual experience is necessary. Even experienced operators can miss checks when site conditions are poor. Newcomers may memorize operation procedures without fully understanding the meaning of the numbers shown. Therefore, it is important for the entire site to have common verification rules.

First, standardize the on-screen check before starting work. Verify the current work data, measurement mode, instrument station, backsight, mirror height, instrument height, units, and correction settings once before taking measurements. You don't need to read everything aloud at length every time, but defining a minimum set of items to check reduces omissions. In particular, it's important not to assume the settings are correct—confirm them immediately after repositioning the instrument, immediately after a change of operator, and immediately after resuming work between morning and afternoon sessions.

Next, decide the order in which the screen display will be read. For example, standardize the on-site workflow so that you first check the work data name, then the measurement mode, then the measurement point name, then the set values, and finally the measurement results. If the order is not determined, operators may only look at the most noticeable numbers and overlook important settings. By formalizing the procedure for reading the screen, even less experienced personnel can check reliably and easily.

Measures are also needed for environments where the screen is hard to see. Direct sunlight, backlighting, raindrops, dust, and working in dark conditions make misreading the screen display more likely. When the screen is hard to see, adjust your body orientation or standing position, wipe the screen, or, if necessary, create shade—prepare a readable condition before operating. Operating by guesswork while the screen is hard to see can lead not only to pressing the wrong buttons but also to misreading numerical values. The display of a total station is a source of information for verification, so as a basic rule do not leave it in a difficult-to-read state.

Extra caution is needed when operating while wearing gloves. Misregistered button presses or touchscreen interactions can move you to an unintended screen or change the measurement mode. After operating, confirm that the screen is in the expected state. Don’t rely only on the tactile sensation of pressing a button—watch the screen changes as you proceed.

In in-house training, it is effective to set aside time to explain the meanings of the numbers displayed on the screen. If you only teach the operating procedures, staff may remember "where to press" but tend to be unclear about "what to look at to make judgments." By checking the meanings of measurement mode, coordinate values, height, difference values, save status, and so on while looking at the actual screen, on-site decision-making will improve. Especially for personnel who are not familiar with total stations, it is important to go through each screen item name one by one and explain how they relate to the drawings and the actual site conditions.

When handing over, share not only the progress of the work but also the state of the screen settings. By indicating which work data is being used, up to which measurement points have been saved, whether the mirror height has been changed, whether correction conditions have been modified, and whether any points were remeasured midway, you can reduce the risk that the next person will misinterpret the screen display. If you are uneasy about relying on verbal communication alone, leaving work notes or a checklist will make it easier to verify later.

Worksite rules to reduce misreads don't need to be complicated. Rather, it's important to build up simple checks that anyone can carry out consistently. Check the display before measuring, look at the results after measuring, confirm the point name after saving, and review the settings when conditions change. Even just standardizing these basics across the whole site makes it easier to reduce errors caused by on-screen displays.

Summary

The display of an EDM (electronic distance measurement instrument) is not just for viewing measurement results. It gathers the information needed for on-site decision making — the current measurement mode, job data, point names, coordinate values, elevation, prism height, instrument height, correction settings, save/status, and so on. For this reason, reading the display correctly contributes not only to surveying accuracy but also to preventing rework, organizing reports, and stabilizing construction quality.

To prevent misreadings, first confirm the measurement mode currently displayed. If you take measurements without understanding which screen you are on and what you are trying to measure, you may end up handling data that do not match your intended purpose. Next, it is important not to confuse coordinate values with height displays. Planar position, elevation, vertical difference, and deviation from design values have different meanings, so you must look at the field that matches your work purpose.

Always recheck the input display for mirror height, instrument height, and correction values. It is not sufficient for numbers to merely appear on the screen; you must confirm that those numbers correspond to the current field conditions. In addition, standardizing units, signs, and the way decimal points are read at the site can reduce errors in transmitting numerical values. Both before and after saving, compare the point name with the observation results to confirm they are recorded as the correct work data.

A total station is a convenient device that, when used correctly, can streamline on-site position checks and as-built management. On the other hand, if misreading the screen display is left unaddressed, it leads to assumptions such as believing measurements were taken, believing data were saved, or believing the results are correct. What’s important on site is to separate trusting the instrument from verifying its displayed information. Even if the instrument is functioning properly, if the settings or readings do not match site conditions, the results may be insufficient.

In daily work, it is important to make a habit of checking before starting work, after repositioning, after changing conditions, and after saving. Deciding where on the screen to look, in what order to check, and who will read aloud and who will repeat makes it easier to maintain stable operations even when the person in charge changes. In particular, at sites where multiple people use a total station, standardizing how the screen display is read can reduce misunderstandings during handovers.

In future fieldwork, it will also be important how the data obtained with a total station is linked to subsequent recording, verification, sharing, and construction management. By correctly reading the screen display and reliably performing on-site checks, and by reviewing the workflow from surveying operations to data utilization, it will be easier to proceed more stably with the management of positional information and the organization of records.