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IS 14488:1998 is the Indian Standard (BIS) for electronic distance measuring instruments (edm). This code of practice provides guidelines for the use of Electronic Distance Measuring (EDM) instruments in surveying. It details the operating principles, sources of error, field procedures for accurate measurement, and the methodology for calibration and applying atmospheric corrections.
Lays down general requirements and methods of test for electronic distance measuring instruments used in surveying.
Overview
Status
Current
Usage level
Specialized
Domain
Geotechnical — Surveying and Geotechnical Investigation
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
Practical Notes
! Atmospheric corrections for temperature and pressure are critical for achieving specified accuracy; never use default or assumed values for high-precision work.
! Always verify the prism constant setting in the instrument matches the actual constant of the reflector being used, as mismatches are a common source of systematic error.
! Regular field checks, such as measuring a known baseline, are essential to monitor instrument performance between formal calibrations.
ISO 17123-4:2012ISO (International Organization for Standardization)
HighCurrent
Optics and optical instruments — Field procedures for testing geodetic and surveying instruments — Part 4: Electro-optical distance meters (EDMs)
Directly corresponds to the field testing and calibration procedures for EDMs.
ISO 17123-5:2018ISO (International Organization for Standardization)
MediumCurrent
Optics and optical instruments - Field procedures for testing geodetic and surveying instruments - Part 5: Total stations
Covers total stations, which integrate EDMs, reflecting modern surveying practice.
BS 7334-8:1992BSI (British Standards Institution), UK
HighWithdrawn
Surveying instruments. Specification for measuring equipment for building construction. Methods for determining the accuracy in use of electro-optical distance measuring instruments (EDMs)
Was the British national standard for determining the in-use accuracy of EDMs.
DIN 18723-4:1990-12DIN (Deutsches Institut für Normung), Germany
HighWithdrawn
Field methods for accuracy tests of survey instruments; electro-optical distance meters
Was the German national standard for field testing of EDM accuracy before ISO adoption.
Key Differences
≠IS 14488 (1998) covers both electro-optical and microwave EDMs, whereas modern standards like ISO 17123-4 (2012) focus exclusively on electro-optical instruments, as microwave EDMs are now obsolete.
≠IS 14488 is a comprehensive 'Code of Practice' covering principles, types, corrections, and use. ISO 17123-4 is more narrowly focused as a 'Field Procedure for Testing', part of a modular series of standards.
≠The ISO standard is more statistically rigorous, specifying formal hypothesis tests (e.g., F-test) and clear criteria for comparing experimental standard deviation with manufacturer specifications, which is less formalized in IS 14488.
≠IS 14488 provides specific atmospheric correction formulae (e.g., from Barrell and Sears, Edlen) in its annex. ISO 17123-4 is less prescriptive, recommending the use of the manufacturer's provided formula which is typically based on more recent Ciddor or updated Edlen equations.
Key Similarities
≈Both standards mandate the determination and application of corrections for instrumental, atmospheric (temperature, pressure, humidity), and geometric errors.
≈Both standards advocate for calibrating and testing EDMs on a multi-pillar, high-precision baseline of known distances to determine instrumental constants and scale errors.
≈Both standards provide procedures for determining the instrument's additive constant (zero error), a fundamental calibration check, by measuring a line in separate, collinear segments.
≈Both IS 14488 and ISO 17123-4 recognize the importance of using stable, high-quality prism reflectors and ensuring they are correctly oriented towards the instrument during testing.
Parameter Comparison
Parameter
IS Value
International
Source
Accuracy Acceptance Criterion
Qualitative comparison against manufacturer specifications; lacks a formal statistical test for acceptance.
Statistical test: Calculated experimental standard deviation (s) must be less than or equal to the manufacturer's specified standard deviation (σ).
ISO 17123-4:2012
Covered EDM Technologies
Explicitly covers Electro-optical and Microwave instruments.
Focuses exclusively on Electro-optical Distance Meters (EDMs).
ISO 17123-4:2012
Atmospheric Correction Formula Source
Provides specific formulae from Barrell and Sears (1939) and Edlen (1966) in Annex A.
Recommends using the formula provided by the instrument manufacturer, assuming it is appropriate for the desired accuracy.
ISO 17123-4:2012
Example Calibration Baseline Layout
Annex B suggests a baseline with specific monument distances (e.g., 0, 30m, 150m, 500m, 1000m).
Annex A suggests a baseline with 4 to 6 fixed points over a range of at least 500m, without prescribing exact intermediate distances.
ISO 17123-4:2012
Statistical Test for Conformity
Describes procedures but does not include a formal statistical hypothesis test for conformity.
Includes a formal statistical test (F-test or chi-squared test) to check if the instrument is within its specified state of adjustment.
ISO 17123-4:2012
Test Measurement Series
Recommends taking 'a set of readings' (e.g., 5 or 10) but is less rigid in its specification across all tests.
Specifies the exact number of measurement series and repetitions required for different test procedures (e.g., 'three series of measurements').
ISO 17123-4:2012
⚠ Verify details from original standards before use
Key Values5
Quick Reference Values
Standard temperature for calibration20 °C
Standard pressure for calibration760 mm Hg
Standard relative humidity for calibration60%
Typical accuracy of short-range EDM±(3mm + 2ppm)
Typical wavelength for infrared EDM0.8 to 0.95 μm
Key Formulas
First Velocity Correction (ppm) = (279.6 - 0.925t - 2.24P) + 0.05e — Simplified formula for atmospheric correction
Tables & Referenced Sections
Key Tables
No tables data
Key Clauses
Clause 4 - Principles of Electronic Distance Measurement
Errors arise from the instrument itself, atmospheric conditions (temperature, pressure, humidity), and operational procedures like instrument/reflector centering (Clause 5).
Why is atmospheric correction necessary for EDM?+
The speed of light/microwaves used by the EDM varies with the density of the air (refractive index), which is affected by temperature, pressure, and humidity. Correction is required to convert the measured path length to a true horizontal distance (Clause 8).
What is a prism constant?+
It's a correction value specific to a reflector prism that accounts for the offset between the prism's optical center and its physical plumb point. It must be correctly set in the EDM instrument.