STUDY OF THE ELECTRONIC TOTAL STATION TRAVEL FOCUSING LENS MOVEMENT INFLUENCE ON THE SIGHTING AXIS POSITION

When carrying out geodetic work inside production shops or on a construction site, it is necessary to significantly change the focusing of the telescope. Refocusing the telescope can lead to a shift in the sighting axis, and, accordingly, to a decrease in the accuracy of angular measurements. The article presents the results of laboratory studies to determine the horizontal error of collimation and vertical index error of the Leica total station for distances from 2 to 84 m. Therefore, after checking the collimation and vertical index error and automatically taking into account their influence, it is allowed performing geodetic measurements at one position of the vertical circle. In particular, this makes it possible to speed up the execution of fan-shaped trigonometric leveling with short sights, which is performed when observing the settlements of the foundations of industrial buildings and structures.

Lissajous-toric knots

A point in the [Formula: see text]-torus knot in [Formula: see text] goes [Formula: see text] times along a vertical circle while this circle rotates [Formula: see text] times around the vertical axis. In the Lissajous-toric knot [Formula: see text], the point goes along a vertical Lissajous curve (parametrized by [Formula: see text] while this curve rotates [Formula: see text] times around the vertical axis. Such a knot has a natural braid representation [Formula: see text] which we investigate here. If [Formula: see text], [Formula: see text] is ribbon; if [Formula: see text], [Formula: see text] is the [Formula: see text]th power of a braid which closes in a ribbon knot. We give an upper bound for the [Formula: see text]-genus of [Formula: see text] in the spirit of the genus of torus knots; we also give examples of [Formula: see text]’s which are trivial knots.

Digitization of the Belgrade Astronomical Observatory's vertical circle observational heritage

The aim of the paper is to present the digitization of the results of last observations of bright stars made by the Belgrade vertical circle ASKANIA N?80118 (D = 190 mm, f = 2578 mm) at the Astronomical Observatory of Belgrade. The observations are mainly made by Djuro Bozhichkovich in the period between 1982 and 1985. All of the found observational data and intermediary results are referenced and presented and some research possibilities are suggested.

Investigation of Systematic Errors for the Hybrid and Panoramic Scanners

The existence of terrestrial laser scanners (TLSs) with capability to provide dense three-dimensional (3D) data in short period of time has made it widely used for the many purposes such as documentation, management and analysis. However, similar to other sensors, data obtained from TLSs also can be impaired by errors coming from different sources. Then, calibration routine is crucial for the TLSs to ensure the quality of the data. Through self-calibration, this study has performed system calibration for hybrid (Leica ScanStation C10) and panoramic (Faro Photon 120) scanner at the laboratory with dimensions 15.5m x 9m x 3m and more than hundred planar targets that were fairly distributed. Four most significant parameters are derived from well-known error sources of geodetic instruments as constant (a0), collimation axis (b0), trunnion axis (b1) and vertical circle index (c0) errors. Data obtained from seven scan-stations were processed, and statistical analysis (e.g. t-test) has shown significant errors for the calibrated scanners.

The Modernization of the Pulkovo Photographic (Photoelectric) Vertical Circle by a CCD Array

The Zverev photographic vertical circle (PVC) of the Pulkovo observatory is in the process of modernization. The features of the vertical circle are: a)Maksutov mirror-lens optical system with small aberrations and wide passband: aperture: 20 cm, focal length: 200 cm, focal scale: 103 arcsec/mm.b)Very compact instrument: 140 cm total length, 60 cm — tube.c)Wide field: 25 × 25 mm = 40′ × 40′. Wide-field imaging can be combined with meridian observations.d)Easily-reversible instrument: reversing takes less than 30 seconds.e)Two divided vertical circles of glass. Photoelectric circle reading microscopes.f)Photographic micrometer in focal plane. This will be changed with a CCD micrometer.