Geoinformation Issues Vol. 3, No 1, 2011
Editorial pages, contents, reviewers of journal "Geoinformation Issues"
editorial pages, contents, reviewers of journal to download
Walyeldeen Godah, Jan Krynski
Validation of GOCE gravity fi eld models over Poland using the EGM2008 and GPS/levelling data
DOI: 10.34867/gi.2011.1
Abstract. Since the mid of 2010, global geopotential models based on GOCE mission data became available. The fi rst two releases of GGMs contained four different solutions while in the third release only two solutions have been generated. In the presented study the available GOCE-derived gravity fi eld models were evaluated in terms of height anomalies and gravity anomalies over Poland with the use of the respective functionals calculated from the EGM2008 geopotential model as well as height anomalies at 184 stations of high precision GPS/levelling control traverse.
The fi t of GOCE gravity fi eld models with the EGM2008 in terms of height anomalies and gravity anomalies measured with a standard deviation is below 10 cm, and 3 mGal, respectively. Their fi t with GPS/levelling height anomalies at the stations of GPS/levelling control traverse is at the level of 10 cm. The results obtained indicate some improvement of the consecutive releases of GOCE gravity fi eld models.
Elzbieta Welker
The infl uence of variations of the Earth’ magnetic fi eld on the elaboration of geomagnetic observations in Poland
DOI: 10.34867/gi.2011.2
Abstract. The increase of accuracy of magnetic measurements generated the need of testing of the infl uence of variations of the geomagnetic fi eld on their elaboration.
On the basis of the magnetic data obtained from European observatories and from magnetic stations operating in 2010 and 2011, the chart of amplitude changes of Y magnetic fi eld component (magnetic declination too) in Poland and the chart of time shift between the records of Belsk Observatory – considered as central observatory – as well as the records from other measurement points were processed.
Data from some geomagnetic stations operating in the 1960. (with records of D, H and Z components) stored in the database at the Institute of Geodesy and Cartography, Warsaw, were re-used to analyse geomagnetic field intensity changes (Uhrynowski, 1962, 1964). The error of transforming analogue data from paper records to the digital form is bigger than amplitude changes of declination D and H component.
The results of Fourier transformation of millions of data from magnetic observatories allowed for mapping the distribution of amplitude changes of Y component and time shift of records from chosen European observatories with respect to Belsk Observatory.
The range of amplitude changes of the X, Y and Z components of the geomagnetic fi eld intensity in Poland is exceptionally small. It reaches only ±2–3 nT which is at the level of the error of geomagnetic data elaboration. The range of time shift of the record from points by eastern border of Poland with respect to those by western border of Poland vary from –6 to +15 minutes for Y component. The test made with data from secular point (repeat station) measurements from 2009–2011 shows that the differences between results obtained without and with time corrections reach only 10-30² for declination and inclination, and 5 nT for total intensity vector length. The use of the magnetograms from Belsk Observatory for the geomagnetic measurement reduction without any time corrections does not, however, generate any signifi cant error infl uencing the measured components accuracy.
Jan Ziobro
Integrated sensor orientation – ground control points for a large-block aerotriangulation
DOI: 10.34867/gi.2011.3
Abstract. The article describes research on the number and distribution of ground control points (GCPs) for large blocks of aerotriangulation using Integrated Sensor Orientation Technology (ISO). The study was conducted through simulation of aerotriangulation. Simulations were performed for fi ve common types of image blocks in Poland and for 2 levels of measurement precision established on the basis of previously performed studies of 19 large blocks constructed in 2008 – 2010.
The utility of the developed rules for designing GCPs distributions were checked in real aerotriangulations of 10 large blocks of images. In the study a reference is made to the accuracy required by Polish national standards, to homogeneity of the results, as well as to the reliability of measurements.
The test results defi ne a suffi cient number of GCPs for the aerotriangulation of large rectangular blocks and for the ribbon block (block of three strips). For rectangular blocks the required GCPs number defi ned as the number of photos per one control point is 40 to 150 and for a ribbon block is 24 to 45, a number that depends on the level of measurement precision and on the shape of the block.
Bartłomiej Kraszewski
Calibration of digital SLR Nikon D3X for the use in digital photogrammetry projects
DOI: 10.34867/gi.2011.4
Abstract. Results of research on calibration of high-resolution digital camera Nikon D3X have been presented. CMOS matrix stability in recording process of digital images, calculation of principle distance as well as principal point, radial distortion and tangential distortion were determined. The interior orientation parameters determined during calibration in test project were examined. All test images were obtained using three replaceable Nikkor lens of 24, 35 and 50 mm focal length. The calibration process was executed in Camera Calibration and Field Calibration modules of PhotoModeler software using convergent terrestrial images. It was also executed for single photo in DLT module of AeroSys software. For the determination of interior orientation parameters of digital camera for each lens the 2D and 3D test fi elds were used. Stability and repeatability of recorded digital images on CMOS matrix were examined on 25 control points which were evenly distributed on a white calibration table. Accuracy of pixel position on the image for 24 mm, 35 mm and 50 mm focal length was 0.06, 0.08 and 0.04 of image pixel, respectively. It was found that interior orientation parameters calculated using the PhotoModeler software for both calibration methods were correctly determined while when using the Aerosys software they were determined with lower accuracy. The very high accuracy of elaboration of a test photogrammetric project for each camera lens was obtained using interior orientation parameters calculated on the basis of convergent images and 3D fi eld.
Agata Ciołkosz-Styk, Adam Styk
Measuring maps graphical density via digital image processing method on the example of city maps
DOI: 10.34867/gi.2011.5
Abstract. During the centuries the main problem on mapping was to obtain the suffi cient and reliable source data; presently, an appropriate selection of the desired information from the deluge of available data is a problem. An availability of large amount of data induces to transfer the possibly rich information by means of map. It often results in overloading the cartographic documents, that is why they become less communicative and diffi cult to read. This situation is well illustrated by the example of city maps which are the most commonly used and thus the most frequently published cartographic products. Many user groups with different needs as well as preparation to read maps use these high volume publications. Therefore, the maps communication effectiveness problem is of particular importance.
The city maps are the most complex cartographic presentations, because the presented areas are the places with the greatest concentration of different kinds of objects and forms of human activity arising from the civilization development. Conveying these specifi c features on the city maps leads to the problem of selecting the most relevant elements of content in terms of user’s needs, since presenting all objects and their characteristics is impossible if the city map readability is to be kept.
Although complexity has been the cartographers’ object of interest for many years, because it exerts an impact on readability and effectiveness of cartographic documents, none of the measures used so far may be applied for automatic determination of complexity of such graphically complicated objects as city maps.
Therefore a novel approach was needed for these applications. For that purpose digital image processing techniques have been proposed and successfully applied by the authors. The analysis of the spatial distribution of the objects’ edges on the map surface, calculated using continuous wavelet transform, is the basis of the proposed measure. The method allows for comparison of complexity of city maps loaded by different type of graphical elements (point signatures, lines, text, etc.). Extended analyses of selected cartographic materials proved the usability of the method for quantitative estimation of city map complexity via formal index.
Andrzej Ciolkosz
Mapping of land use changes in Poland using Earth observation data
DOI: 10.34867/gi.2011.6
Abstract. Mapping of land use for the needs of reconstruction of the country was one of the main tasks of the Head Offi ce of the Land Surveying set up after the Second World War. Up to present day such map has not been made despite of many attempts and the high demand for this type of map primarily by the spatial economy. The main reason was the lack of raw materials and high cost of fi eld works.
The situation changed with the launch of Landsat satellite. Images taken by this satellite were used for the preparation of land use map covering the entire country. They were also used to compilation the land cover databases developed within the three CORINE Land Cover (CLC) projects in 1990, 2000 and 2006. Comparison of these databases allowed an analysis of land use changes occurred within 16 years. These changes were relatively small, far below expectations.
CLC database was also compared with a map of land use developed on the basis of topographic maps from the 1930’s. The comparison showed changes that have occurred on the surface representing almost 10% of the total area of the country. They reveal both some effects of hostilities, the current expansion of the country, as well as the effects of natural disasters which hit Poland in recent years.
Images taken by Landsat have also been applied to study the damage of forests in the Sudety Mountains. Several degrees of damage to spruce stands have been distinguished on the basis of satellite images. They were also used to study the development of brown coal mine and its impact on dropping the groundwater level in the vicinity of mine as well as to determine the development of Warsaw built-up areas in the last 80 years.
Katarzyna Dąbrowska-Zielińska, Andrzej Ciołkosz, Alicja Malińska, Maciej Bartold
Monitoring of agricultural drought in Poland using data derived from environmental satellite images
DOI: 10.34867/gi.2011.7
Abstract. In Poland one can observe a lack of suffi cient amount of rainfall during plant growth season. This results in the occurrence of agricultural drought and the consequent drop in crop yields. For the early detection of drought, satellite images taken by environmental and meteorological satellites have been used. On the basis of these images various plant indices like NDVI, VCI and TCI have been determined. Analysis of changes in these indices allows preparation of maps showing the emergence and extent of drought. These vegetation indices were also used in the model of cereal yield forecast. Comparison of the results provided by the model show a high conformity with the results published by the Polish Central Statistical Offi ce. Elaborated model estimating crop yield reduction due to drought, based on satellite-derived data allows venture of measures to mitigate results of drought and prevent the lowering yields by artifi cial irrigation.