This paper is an attempt to bring together and summarize the research, based on the use of the new opportunities provided by the development of optoelectronic for engineering geodesy works. Optical fiber solutions, which are described in this article, have many advantages. One of the most important is the lack of electrical power and indifferent behavior towards strong electromagnetic fields. In addition, this type of solutions are characterized by transmission the measuring signal over long distances, which allows to eliminate the observer from a dangerous work environment. Of course, these methods have some disadvantages. The waveguides are characterized by high fragility and sensitivity of alkaline. Moreover, the prices for fiber-based systems are very high, the reason for this is the high fiber production costs. It should be noted, however, there have been recently observed a significant decline in prices. Taking into account the long-term viability and stability of the sensor there is noticed the upward trend for their use. This article presents a preliminary division of use of waveguides in the geodetic works. Author describes passive and active ways of using fiber as a part of the measurement system. A significant part of the study is devoted to the description of the active optical fiber sensors. This content refers to the theoretical basis of their operation and the number of measurement points which can be simulated by appropriate selection of the solution. There were specified in comparison types of the measured parameters and precision of their determination for each of the presented sensors. The practical part presented the sensor system in the form of a “delta” rosette and selected effects of the acquisition, processing and visualization of data using dedicated software. At the conclusion, there were classified certain real objects applications and elaborated on the theoretical possibility of using these systems.
Geographic Information System, ArcGIS, database, analysis, Moravian wine trails, cycletourism
The paper deals with the creation of a geographic information system (GIS) with the main emphasis of its use in cycling. The data collection on the trail, obtaining of the maps data and their processing and transformation into the System – Uniform Cadastral Trigonometric Network (S-UCTN) are described. The import of geodata, geodatabase creation and a graphic representation design of cycle tracks and infrastructure are explained. The conclusion is devoted to a real use of GIS – tasks of searching and querying, creating of outputs, and are also the possibilities to export to other formats (ArcReader, ArcPad, ArcScene and GeoPDF) and platforms (PDA, tablet, web map server) have been explored.
ACCURACY ASSESSMENT OF THE HEIGHT COMPONENT OF THE AIRBORNE LASER SCANNING DATA COLLECTED IN THE ISOK SYSTEM FOR THE WIDAWA RIVER VALLEY
Kamila Pawłuszek, Marcin Ziaja, Andrzej Borkowski
airborne laser scanning, DTM, ISOK, accuracy
The main application of airborne laser scanning (ALS) technology is the data collection for creating high quality digital elevation models (DEM). In Poland, almost entire area of the country has been scanned for the implementation phase of extraordinary hazards (mostly water hazards) protection system (ISOK). The quality of acquired data was a subject of inspection at the acquisition time. In this study, an alternative methodology was applied to evaluate the height component accuracy of the ALS data. For the inner accuracy evaluation (data consistency), subsets of the point cloud representing flat surfaces (e.g. roofs) were used. This data was approximated by a plane using least squares method. Based on residuals between approximated plane and the ALS data a mean square error was calculated. Numerical tests were executed for 36 planes representing roofs, roads, meadows and arable fields. For the anthropogenic areas the estimated mean square error is similar to the accuracy of distance measurement by a scanning system and ranges from two to four cm. In the case of natural surfaces that are characterized by high roughness, the error increases to a value of three to twenty cm. In order to assess the external (absolute) accuracy of the ALS data, heights of the reference points measured by geodetic techniques were compared with the heights of corresponding (neighboring) ALS points. The accuracy assessment was carried out for three classes of the land use (arable fields and meadows, roads, forests) and four test areas, located in the area of Widawa River Valley. The absolute accuracy varies for different types of land use from slightly more than ten cm for roads to more than double the value for forests.