Geodetski Vestnik (Dec 2018)

The influence of artificial illumination of invar levelling rods on the measurements with digital levels

  • Štefan Rákay,
  • Slavomír Labant,
  • Karol Bartoš,
  • Katarína Pukanská

DOI
https://doi.org/10.15292/geodetski-vestnik.2018.04.619-629
Journal volume & issue
Vol. 62, no. 4
pp. 619 – 629

Abstract

Read online

Since the digital levels operate on the principle of image processing of the bar code of levelling rod, recorded by a CCD sensor, the proper lighting (i.e. illumination of the bar code) is important to achieve accurate results. The prevention of inappropriate lighting conditions is important for the correct recording of the image of bar code section. This paper examines the systematic error as a function of the angle of incidence at which an bar code is illuminated by artificial lighting in low light conditions. Further, the procedure of measurements and the analysis of results for the identification of such errors is proposed. The results of experimental measurements highlight the inappropriateness of bar code illumination at an angle of incidence of more than about 45 °. From the practical measurements, it was found that the angle of incidence 55 ° corresponds to an error of about 0.02 mm, which is twice as much as the resolution of the height measurement determined by the manufacturer.

Keywords