FAQ Measuring Accuracy

This is infrequently used content, but to expand accessibility to a wider audience we are using a machine for translation. Please excuse any unanticipated translation errors. -Thank you, Leica Geosystems.​

What are favorable/unfavorable measuring conditions?

Favorable/average measuring conditions:

  • Materials with good reflecting characteristics, meaning they reflect the laser beam in a divergent 
    (not mirrored!) manner
  • Laser dot is brighter than the ambient light
  • Operating within the allowable temperature range 14° to 122°F (-10° + 50° C)

 Unfavorable measuring conditions:

  • Highly reflective surfaces
  • Highly absorbing surfaces, such as wet or dark surfaces
  • Operating at the limits of the allowable temperature range
  • Not waiting for temperature calibration
  • Very intensive ambient light
  • Shimmering
  • For optical and safety reasons, do not measure against colorless liquids (water) or glass

What accuracy of my Leica DISTO™ can I expect when using the functions for indirect measurements? 

Some Leica DISTO™ devices are offering the possibility of measuring heights or widths using indirect measurement functions with Pythagoras theorem or with inclination sensor. Generally it is recommended to measure any height directly at the object by using simple distance measurement. If this is not possible because the object is not accessible or a high accuracy is not needed measurements can be also taken with the indirect measurement functions. (More information can be found here.)

How accurate is Leica DISTO™ at 0.5m, 1m … to 200m?

The measurement deviation for Leica DISTO™ devices is not directly proportional to the measured distance. Therefore the accuracy of a Leica DISTO™ remains constant until a range specified in the manual. After this range the accuracy will change by a value proportional to the distance which is also specified in the operation manual. In many cases a maximum measurement deviation will not be exceeded.
E.g. the Leica DISTO™D3 is having an accuracy of 1mm up to 10m. After this the deviation will increase by 0,025mm/m (so at 30m the accuracy will be 1,5mm). After 30m the deviation will increase by 0,1mm/m (at 100m the measurement deviation might be 8,5mm).

Please note that measurement conditions may have an influence on the accuracy. Read more about this in the FAQ for "typical accuracy". The tolerance is not proportional to the measured distance, it is the same over the entire distance. However, over long distances, additional errors of +/-5 ppm (parts per million) (+/-0.5mm/100m) come into play. 

What does the term "typical" in relation to the product accuracy mean?

Leica Geosystems specifies its DISTO™ for a standard deviation of 2б (Sigma). 

The term typical means for measurements under normal measurement conditions. Targets in very bright conditions or bad reflecting targets may have an influence on the measurement accuracy. We therefore recommend, especially if high accuracy is required, the use of target plates or shading of the targetpoint.

What is measuring accuracy?

Measuring accuracy is specified in accordance with ISO-recommendation ISO/R 1938-1971, with a statistical safety of 95% (2s, i.e. two-fold standard deviation). Typical measuring accuracy is based on average measuring conditions within the specified measurement range. It is not valid for special application functions and calculations, such as Pythagoras and is not valid in tracking mode (continuous tracking).

How can I monitor my measuring equipment on my own?

Monitoring of measuring equipment for Leica DISTO™ –users who perform the required monitoring themselves, in accordance with their quality management systems: Measure an easily accessible distance of 2 to 10 m with a distance measuring instrument approved by your national bureau of standards. Make 10 measurements over the same distance. Determine the deviation of your measurements from the actual distance and calculate the standard deviation from the results. Record the value and set the time for the next series of measurements. Repeat these check measurements regularly, especially before and after important measuring tasks. Mark the Leica DISTO™ with an”inspected” sticker and protocol the entire monitoring process. Your Leica DISTO™ meets the specified accuracy, if the standard deviation is equal to or less than the value stated as the typical standard deviation. A Leica DISTO™ checked on the test distance works with the specified accuracy over the entire specified measuring and temperature ranges. For more information please download enclosed PDF.

Monitoring of Measuring Equipment (en)