This paper presents Satellite Maps from the years 1968 and 2006 and the first unique Aerial Map of the area of the Bledowska-Desert in Little-Poland from the year 1926 with the clearly visible environmental changes by forestation and vegetation of plants. The origin, its decline and the recently undertaken measures to win back the desert are described, a rarity of geologic nature in the European graduation. The Desert-Landscape was put within the scope of the project NATURA 2000 on the list of the EU-Commission of the areas of common meaning (GGB) in the continental biographical regions.
Problem of antenna phase center variations in satellite leveling
phase center variations, GNSS data processing, satellite leveling, geoid models, normal heights
Satellite leveling is the procedure used to determination orthometric (normal) heights, on the base of ellipsoidal heights derived with GNSS techniques and additional information which make possible geoid (quasi-geoid) undulation determination. Geoid to ellipsoid separations can be get from geoid models, which accuracy in last years has significantly grown. However, for accurate determination of orthometric (normal) heights it is also important exact determination of ellipsoidal heights from GNSS measurements, which accuracy degrades a number of factors. One of the most important in heights determining, is antenna phase center variations problem. It is well known that magnitude of antenna phase center variations (PCV) can reach several centimeters. Unfortunately part of so-called commercial GNSS post-processing software does not include corrections to the antenna PCV. The paper presents results of solutions this problem with help of a subroutine which introduces PCV corrections to code and phase observations. This approach has been tested using GPS data at four measurement points. Three different types of antenna were used in observations. Processing GPS observations ware done with Ashtech Solutions and Topcon Tools software. The heights derived with satellite leveling were compared to heights got from geometrical precise leveling. The results of studies on one hand confirmed significant influence of antenna PCV onto exactitude of heights determination as well as usefulness of proposed procedure to introducing correction to GNSS observations.
Application of free geomatic software for statutory community tasks
Milena Nowotarska, Robert Szczepanek
free software, geomatics, local government, QGIS, gvSIG
The paper describe analysis of potential use of free geomatic software in local government work, on the example of two popular programs. Presence of polish versions, implementation of standards and functions, simplicity of use and technical support were taken into consideration. Based on selected task, procedures of their completion were analysed and described. As free software is available free of charge, the only cost is related to implementation and training. As result of analysis it was stated, that QGIS is an interesting alternative for presently used in Poland tools, while gvSIG at the moment can be recommended mainly for data display, as gvSIG doesn’t support properly polish letters coding. Both programs are simple in operation and contain all basic functions, important from local government employee point of view.