This paper aims at developing the 3D land model of Bencecu de Sus, Timiş County, Romania, as a result of land survey. Land survey was done with a Leica GPS 1200 equipment, an extremely powerful instrument, that contains a number of applications. GPS 1200 can be used as either reference or rover for static or kinematic measurements (RTK); it can be used for topographic surveys, tracing, monitoring, and seismic measurements. GPS 1200 receivers are designed to work in the hardest conditions being able to operate in immersions up to 1 m; it is shock proof and vibration proof, it operates on rain, in dust, sand, and snow, at temperatures between -400C and +650C. In this paper, we used the RTK (Real Time Kinematic) method for GPS measurements using, for the 3D model of the land, the reference station in Timisoara, Romania, i.e. TIM_2.3. The measuring engine used by Leica GPS 1200 is of the SmartTrack type which reaches satellites in just a few seconds: it is ideal for the areas with obstructions where other receivers cannot reach any position. The antenna used to achieve the work is of double frequency (GX 1230) with SmartTrack and is designed to also support GLONASS signals, GPS L15 signals, as well as the signals of the future European GPS network GALILEO. Leica GPS 1200 uses a keyboard of the QWERTY type, touch screen or common screen and allows direct visualisation of the land survey; it has also available the ZOOM and PAN functions. Data can be exported directly by the GPS 1200 receiver but, for the present paper, data download was done with the Leica Geo Office Combined Programme. The reference system of the GPS is WGS 84 (World Geodetic System 1984) that is defined like the ITRF system of coordinates of the determined land points. Using on an increasingly larger scale of the positioning systems through satellite and of the global systems of mapping through satellite to carry out geodesic works can bring about serious practical difficulties if the results need to be reported to older maps or digital data. The main difficulty consists in turning geocentric data into local data describing old data or vice versa. After downloading, data processing and turning coordinates from ETRS89 into STEREO’70 with the TransDatRO 4.01 application, we calculated the 3D land model with the TopoLT Programme, a programme functioning on the AutoCad platform. Building up a 3D model consists in developing a continuous area through interpolation starting from the field data. Topographic survey, due to the quality of the data provided, is one of the most important methods of acquiring data at local scale and particularly of completing existing datasets with detail data. Using GPS (Global Positioning System) to acquire the data necessary for the development of the Numerical Land Model is a more economic alternative for classical topographic survey.
3DModel, GPS, ETRS89, STEROGRAFIC 1970, TopoLT, TransDatRO, WGS 1984
Presentation: oral