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Proceedings of the Institute of Geodesy and Cartography - No 106, Vol. L

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price: 35 PLN

Elżbieta Welker, Andrzej Sas-Uhrynowski
Changes of magnetic declination in the period of 1941–2000 at the former eastern Polish territories
Elaboration of the magnetic charts for the country demands some data at the points located outside of the country border. It concerns all magnetic components, declination including. Otherwise, one must determine the isogons running to the line of border, using extrapolation. If the magnetic field distribution is complicated, it leads to errors. In case of the northern and eastern Polish areas, the errors in declination may reach even several degrees. Usually the data from abroad may be obtained by exchange with the neighbouring countries. The necessary declination data from Germany, Czechs and Slovakia have been obtained by exchange. At the North, the magnetic survey on the Baltic Sea has been performed in the period 1970–1990 within the frame of the Polish-Russian co-operation. But, unfortunately, it was impossible to obtain the data from the western regions of the former Soviet Union.
Luckily, the old magnetic data, covering also the former Polish territories, which presently belong to Russia (Kaliningrad Region), Lithuania, Belarus and Western Ukraine, have been found in the archive. There  were catalogues of declination and maps of declination worked out in the period of 1935–1941 by Polish and Lithuanian specialists, and German catalogues as well as maps of the magnetic deviation, worked out for the epoch 1941.5 by the Wermacht Topographic Service. 
The magnetic observatories to the East of Poland are far apart each from another, therefore there were some problems to determine the changes of declination, which had taken place since 1941. The lack of magnetic repeat stations on these territories has made additional difficulties. To solve the task, at first the data from magnetic observatories, published by Golovkov until 1980, have been used. The declination data for the next period 1980–2000  have been obtained from the observatories Surlari, Panaguriste, Hurbanovo, Pleshchenice and Lvov as well as from Golovkov, who still collects the observatory data. The results of observations at the Polish repeat stations at the East: Ogrodniki, Bełżec and Cisna, have also been used to control the data from Lvov. The period 1941–2000 has been divided into three 20-year intervals and the changes for each interval have been determined separately. At the end, all changes have been added up and applied to reduce the archival data to the epoch 2000.5.
In 1996, the co-operation with Lithuanian and Belarussian specialists begun. It resulted in common research of magnetic secular variations on our territories. Eleven magnetic repeat stations in Belarus and six stations in Luthuania have been established within the framework of this co-operation. The measurements at the stations have been performed twice. Received results have been also used to control the archival data reduced to the epoch 2000.
The work shows that magnetic repeat stations are indispensable to analyse the time and space distribution of secular variations, especially in the regions where the magnetic observatories are sparsely located.

Zbigniew Bochenek
Preparation of the method of land use change detection on the basis of analysis of multitemporal high-resolution satellite data
Results of complex studies aimed at preparation of optimal method for detection of land use changes on the basis of digital analysis of multitemporal satellite data were presented in the article. Various types of satellite images, characterized by different ground and spectral resolutions – Landsat TM, SPOT HRV, IRS 1C and QuickBird – were used in these studies. At the preparatory phase methods of geometric and radiometric correction, as well as normalization methods, were analyzed. As a result of these works normalization method, optimal for comparing multispectral, multitemporal  images, based on stable in time land cover types, was determined.
At the second stage of the works methods of creating change detection maps on the basis of multitemporal satellite data were thoroughly analyzed. The following approaches were studied:

• Method of subtracting radiometric values in particular spectral channels
• Method of subtracting normalized difference vegetation index
• Method of comparing principal component images
• Classification of multitemporal dataset
• Method of comparing two classification images
• Method of analysis of change vectors

As a result of the performed research works usefulness of the above mentioned methods was assessed, considering precision of distinguishing changes of land use within urban areas. In case of the methods based on subtraction of original and transformed images the work was concentrated on finding optimal threshold levels for separating changed and non-changed areas. It was found, that values of threshold level depends on type of satellite data and on spectral band. In case of the methods based on classifications the research works were aimed at determination of the method, which enables to distinguish the detailed land use/land cover classes, especially within urban areas, with the adequate accuracy. As a result of comparison of various methods it was found, that the method of independent classification of satellite data collected at different dates and their comparison is the most effective method for creating change detection maps. For urban areas, characterized by very complex land use pattern, method of object-oriented classification, which allows to take into consideration spectral and non-spectral image features, proved to be optimal. Application of this method for Warsaw area enabled to distinguish four levels of urban density, characterized by various contribution of anthropogenic objects and green areas.
Comparison of two classification maps, prepared with the use of this method, allowed for preparation of change detection map, presenting character of changes of land use and land cover within Warsaw area. This map represents changes concerning transition of non-urban areas to built-up land and transformations related to urban density.

Krystyna Stankiewicz
Application of neural networks to classification of ENVISAT and ERS microwave images for crop identification
Method of classification of ENVISAT and ERS microwave images with the use of neural networks was presented in the article. Features of the classified images, which are important for crop identification, were described. Author presented the successive steps, which were done in order to prepare microwave data for classification. Classification was performed for mean values of the modified backscattering coefficient, related to image segments, which represent homogeneous areas. The results of classification done for the whole set of images and for selected subsets were presented in the article.

Krystyna Stankiewicz
Crop recognition on ENVISAT and ERS microwave images
The presented work was aimed at examination of possibilities of crop recognition on microwave images. The study was based on ENVISAT and ERS images, collected from the end of April till August 2003. Justification of selection of images and method of their processing, in order to prepare them for interpretation, were presented in the article. The necessary field information was collected from three test sites located in Poznań region. Analysis of cluster separability in spectral space defined by images was applied for examining crop recognition. Using variance analysis possibility of application of the modified backscattering coefficient was verified. Mean values of this coefficient γ were calculated on the basis of image data.
The following conclusions were drawn from the analyses:

• rape, sugar bets, corn, alfa-alfa and cereals are recognizable on microwave images;
• rape can be discriminated already at the end of April / beginning of May on the basis of at least two ENVISAT microwave images, using different polarizations;
• discrimination of various crop species is possible, but due to signature similarity recognition of particular species can be significantly dependent on acquisition dates and on terrain conditions, first of all on soil moisture;
• effectiveness of crop recognition greatly depends on number of microwave images and dates of their acquisition;
• selection of images collected with various polarizations is crucial for crop recognition;
• large angle of incidence of microwave beam is favourable for crop recognition.

Vegetation period in 2003 was not typical due to extremely low rainfall level. Conclusions concerning crop recognition are not universal, because they were drawn for conditions characterized by very low soil and vegetation moisture.

Albina Mościcka, Janusz Ostrowski
Integration of cartographic and statistic presentation of  patial information contained in raster soil-cartographic database
The article concerns problem of logical integration of cartographic and statistic data. This process is based on creating integrated thematic layers in the course of modeling and on integration of the resultant data, while preparing content of thematic map, through its provision with statistic information, e.g. in the form of diagrams or the other forms of cartographic presentation. It is planned to prepare simultaneously cartographic and statistic documentation presenting lists with the acreages of the mapped elements. Authors presented in the article methodical solutions and their practical application on the example of raster, marginal soil database, created on the basis of spatial reference grid.

Agata Hościło
Succession of scrub vegetation within middle basin of the Biebrza National Park
Analysis of aerial photographs taken in 1963 and 1997, and 2000 Landsat ETM+ image reveals, that process of succession of scrub vegetation within middle basin of the Biebrza National Park is highly advanced.  In the course of nearly 40 years significant increase of areas covered with scrub vegetation characterized by various densities was observed.  That situation is mainly caused by discontinuance of agricultural usage of grasslands and by progress in marshland drainage. On the area of Biebrza marshlands also rapid recession of scrub vegetation is locally observed (in the triangle delimited by Woźnawiejski channel, Ełk and Jerzgnia rivers); it is caused by natural or anthropogenic accidental events – mainly fires.