Updating of digital topographic maps in the new national spatial coordinate system: case Fergana valley in Uzbekistan

The classical geodetic coordinate system (CS42) in Uzbekistan uses the Krasovsky ellipsoid. The implementation of new information technologies, such as the Global Navigation Satellite System, became the basis for the development of a new national open geocentric coordinate system. This paper describes the development of a distortion grid for transforming horizontal spatial data from the local geodetic datum CS42 to a geocentric datum WGS84 for 1:100000 scale maps of the Fergana Valley in Uzbekistan. A first version of the distortion grid file has been created for transforming between CS42 and WGS84 for the whole territory of the country. The significant influence of the longitudinal drift of the region has been confirmed. The grid was used to transform topographic maps at a scale of 1:100000 for the Fergana Valley. Changing the map datum has shifted the grid of coordinate systems by 70 m in the East and 7 m in the North.

TRANSFORMATION OF SPATIAL DATA INTO THE STATE GEODETIC COORDINATE SYSTEM OF 2011 IN GIS SOFTWARE

The article describes the implementation of the coordinate transformation procedures in GIS (on the example MapInfo Professional) between the existing in the country coordinate systems (SC-42, SC-95, MCS, based on them) and SCS-2011, allowing the reader to learn how to calculate the parame-ters of Helmert transformations between these coordinate systems using GOST 32453-2017. The article notes the problem of the transformation accuracy on the global parameters established by GOST 32453-2017 and the resulting need to determine local versions of these parameters, leading to the creation of uncoordinated spatial data sets in GSK-2011, additional costs and complicating work of consumers. In order to solve this problem, it is proposed to consider the formulation of the task of transition to the implementation of cadastral work from coordinate systems based on SС-42 to MСS, created at SCS-2011, as an actual problem of improving the geodetic support of the country

Combined Positioning Device for the Control System of the Microtunnel Boring Machine

The issues of developing a combined positioning device for the microtunnel boring machine control system are considered. A device combining laser and inertial methods of determining coordinates is proposed, which provides the possibility of determining the coordinates and spatial position of the tunneling shield during the construction of straight and curved tunnels by the pushing method. A method for connecting the positioning device with the microtunnel boring machine control system based on the RS-485 wired interface is proposed. A method for calculating coordinates has been developed that takes into account the rotation of the local coordinate system relative to the local geodetic coordinate system.

Short-Term Realization of the ITRS with GNSS/SLR/VLBI/DORIS

<p>International Terrestrial Reference Frame (ITRF) is the realization of the International Terrestrial Reference System (ITRS), which can be used for the variety applications such as earth research, surveying and mapping. 2000 National Geodetic Coordinate System (CGCS2000) has been established and widely applied as a long-term reference frame in China, however, a software for short-term reference frame establishment is also developed to provide high accuracy applications based on the fusion of GNSS/SLR/VLBI/DORIS. We analyzed the covariance from sinex format of the GNSS/SLR/VLBI/DORIS and the quality of local ties. The errors between the local ties and the ITRF2014 within 1cm was 89% in north direction and 85% east direction. We used inner constraints as the method of datum realization and Helmert variance component estimation for giving the weight of different space geodetic GNSS/SLR/VLBI/DORIS. Finaly, short-term terrestrial reference frame realization software can produce the weekly, monthly and annual frame products for high accuracy applications.</p>

Geocentric Coordinate Systems and Actual Problems of Modernization of the State Geodetic Network

The article describes the state of the geocentric coordinate system of the Russian Federation. Current problems of the geodetic coordinate system are described, and a method for solving this problem is proposed.

Method for determining the normal heights from satellite data, taking into account the deviations of the plumb lines

Currently, using in Vietnam for constructing is normal height and method of leveling geometry. During the construction, it is necessary to transfer height through difficult terrain, such as large rivers or high mountains. In such situations, the transfer of altitude with the help of GNSS will allow to reduce labor costs in comparison with the transfer of altitude using the geometric method. However, the key issue is interpret the altitude defined by the GNSS to a normal height with an accuracy that meets the requirements for leveling grids in engineering geodesy. In this article has been offered algorithm for determining normal altitudes from satellite data and taking into account the deviations of the plumb line. Using GNSS technology are determined coordinates in the geodetic coordinate system or in the spatial one corresponding to the ellipsoid WGS-84. The technique for determining the normal heights from the data of satellite determinations is considered. A computational algorithm is proposed that includes taking into account the deviations of the plumb line and their determination by rotation of the ellipsoid, and also assuming the presence of geometric leveling data. An example of the implementation of an algorithm on a specific object is shown.

Rapid Mapping Method Based on Free Blocks of Surveys

While producing large-scale larger than 1:2000 maps in cities or towns, the obstruction from buildings leads to difficult and heavy tasks of measuring mapping control points. In order to avoid measuring the mapping control points and shorten the time of fieldwork, in this paper, a quick mapping method is proposed. This method adjusts many free blocks of surveys together, and transforms the points from all free blocks of surveys into the same coordinate system. The entire surveying area is divided into many free blocks, and connection points are set on the boundaries between free blocks. An independent coordinate system of every free block is established via completely free station technology, and the coordinates of the connection points, detail points and control points in every free block in the corresponding independent coordinate systems are obtained based on poly-directional open traverses. Error equations are established based on connection points, which are determined together to obtain the transformation parameters. All points are transformed from the independent coordinate systems to a transitional coordinate system via the transformation parameters. Several control points are then measured by GPS in a geodetic coordinate system. All the points can then be transformed from the transitional coordinate system to the geodetic coordinate system. In this paper, the implementation process and mathematical formulas of the new method are presented in detail, and the formula to estimate the precision of surveys is given. An example has demonstrated that the precision of using the new method could meet large-scale mapping needs.

Computation of Radiation Budget on an Oblate Earth

The effects of the earth’s oblateness on computation of its radiation budget from satellite measurements are evaluated. For the Clouds and the Earth’s Radiant Energy System (CERES) data processing, geolocations of the measurements are computed in terms of the geodetic coordinate system. Using this system accounts for oblateness in the computed solar zenith angle and length of day. The geodetic and geocentric latitudes are equal at the equator and poles but differ by a maximum of 0.2° at 45° latitude. The area of each region and zone is affected by oblateness as compared to geocentric coordinates, decreasing from zero at the equator to 1.5% at the poles. The global area receiving solar radiation is calculated using the equatorial and polar axes. This area varies with solar declination by 0.0005. For radiation budget computations, the earth oblateness effects are shown to be small compared to error sources of measuring or modeling.

Chinese Geodetic Coordinate System 2000 and its Comparison with WGS84

It is a general trend to adopt the geocentric coordinate system as a geodetic datum for the international measurement community. The definition and realization of Chinese geocentric three-dimensional coordinate system (CGCS2000) which has been employed since July 1st, 2008 were introduced in detail. The defining parameters and derived constants of the reference ellipsoid used were given. The comparison between CGCS2000 and WGS84 was carried out. The differences of geodetic coordinates of a point between the two coordinate systems, normal gravity and vertical gradient of normal gravity on the two ellipsoids caused by the change of the flattening of the ellipsoid were analyzed. The results show that these differences could be neglected in view of present measurement accuracies.