The Effect of Mounting Height on GNSS Receiver Positioning Accuracy in Forest Conditions

In spite of the high prices of GNSS receivers, many users decide to invest in this equipment because of the high accuracy of X, Y and Z data capture. Measurements in forested environments are affected by the increased positional error because of the signal multipath effect caused by trees. The main idea of this paper is to raise the antenna of a GNSS receiver during measurements, in order to reduce the multipath effect in the highest part of forests. A 15 meter pole was used in order to capture the GNSS signal at a height of 5, 10 and 15 m above ground level, in various forest conditions. The main factor, which determines the precision and accuracy, is the operational mode of the receiver. When in the FIXED mode, the results obtained are more reliable than those obtained when in the FLOAT mode. Due to difficult conditions in the forest stand, FIXED mode occurrence is not always possible, but much more likely at higher elevations. The FLOAT mode, however, is more likely to occur in the forest conditions and the obtained accuracy of the X and Y coordinates was ±0.81 m and 1.11 m for the elevation (Z coordinate). The best results were achieved for X and Y coordinates at an altitude of 10 m in a leafless state with an average error of ±0.54 m for the FLOAT mode. We cannot assume, therefore, that raising the GNSS antenna will improve the precision and accuracy in every case

Geomatyka w nauczaniu leśników na uczelniach rolniczych

The idea for this publication was barn in June 2015, during a meeting of Polish teachers involved with Geographic lnformation Systems. The meeting was initiated by the Department of Geoinformation, Faculty of Geographical Sciences, University of Łódź, which received a grant to organize it. The discussion and presentations from academic teachers representing various universities in Poland were very interesting and sometimes heated. it would be advisable for other educators to familiarise themselves with the aspects of GIS education among Polish geographers, foresters, surveyors and other users. The experience of Geoinformation education in Poland is still modest, so the views of people who have been involved at Polish universities with it since the 1990s should be interesting to readers. Geographic lnformation Systems (GIS) – the integration of environmental and climate issues as an important factor for economic development and quality of life – an innovative second-degree studies. Akronim GIS-E-QL: GIS for environment and quality of life. Project objectives: The main aim of the project is to start-up attractive and innovative second­ degree studies – geoinformation in mutual cooperation of the FGS and the FMCS, students education, improving the competence of academic teachers, conference organization, publishing, cooperation with practitioners and establishing contacts with partners from Norway. This aim is consistent with the “Ana lysis of the economy's demand for graduates in key field of strategy in the context of the Europe 2020” 2012 and “Strategy for development of higher education in Poland 2020”, in the field of promoting innovative courses, formed collectively with practitioners, raising awareness of the environment. Joint actions of educators and practitioners, supported the by the strengthening of university's hardware, software and spatial data, will ensure a high quality project. The existing cooperation with practitioners indicate that further training is necessary and they would like to see postgraduates in their institutions. The final beneficiaries of the project will be the students and the academical teaching staff and indirectly the economy of the region. Students who graduate will be the main recipient of the project, the next will be teaching staff who will have contact with the practices and Norwegian partners with similar interests. In broad terms the project will benefit Polish and European economy and environment.This book has been prepared within the project „Geographic Information Systems (GIS) – the integration of environmental and climate issues as an important factor of economic development and quality of life – an innovative second-degree studies” supported by a grant from Norway through the Norway Grants and co-financed by the Polish funds. (Agreement No FSS/2014/HEI/W/0114/U/0013)

GIS w polskiej edukacji wyższej – dyskusja

The idea for this publication was barn in June 2015, during a meeting of Polish teachers involved with Geographic lnformation Systems. The meeting was initiated by the Department of Geoinformation, Faculty of Geographical Sciences, University of Łódź, which received a grant to organize it. The discussion and presentations from academic teachers representing various universities in Poland were very interesting and sometimes heated. it would be advisable for other educators to familiarise themselves with the aspects of GIS education among Polish geographers, foresters, surveyors and other users. The experience of Geoinformation education in Poland is still modest, so the views of people who have been involved at Polish universities with it since the 1990s should be interesting to readers. Geographic lnformation Systems (GIS) – the integration of environmental and climate issues as an important factor for economic development and quality of life – an innovative second-degree studies. Akronim GIS-E-QL: GIS for environment and quality of life. Project objectives: The main aim of the project is to start-up attractive and innovative second­ degree studies – geoinformation in mutual cooperation of the FGS and the FMCS, students education, improving the competence of academic teachers, conference organization, publishing, cooperation with practitioners and establishing contacts with partners from Norway. This aim is consistent with the “Ana lysis of the economy's demand for graduates in key field of strategy in the context of the Europe 2020” 2012 and “Strategy for development of higher education in Poland 2020”, in the field of promoting innovative courses, formed collectively with practitioners, raising awareness of the environment. Joint actions of educators and practitioners, supported the by the strengthening of university's hardware, software and spatial data, will ensure a high quality project. The existing cooperation with practitioners indicate that further training is necessary and they would like to see postgraduates in their institutions. The final beneficiaries of the project will be the students and the academical teaching staff and indirectly the economy of the region. Students who graduate will be the main recipient of the project, the next will be teaching staff who will have contact with the practices and Norwegian partners with similar interests. In broad terms the project will benefit Polish and European economy and environment.The experience of Polish scientists and educators in the GIS has not been as long as mentioned by Michael F. Goodchild who jointly with Ross Newkirk (Goodchild 2006) started the fi rst GIS training course at the University of Western Ontario in Canada in 1975. Discussions on the scope of knowledge included in the GIS have continued at most universities that have offered such classes. In 1988/89, owing to the National Centre for Geographic Information and Analysis (NCGIA), the 3-volume document of over 1000 pages was put together to include curriculums, student materials and other teaching aids. We have good models and we can use them. Meetings and discussions about the GIS education have been and still are regularly held all over the world (Forer P., Unwin D. 1999). When employees of Polish universities were starting to learn the GIS software and possibilities, Morgan J. M., Fleury B., Becker R. A. (1996) had already identifi ed over 800 higher education institutions all over the world that had offered at least one GIS course. The rapid development of new technologies, methods, the creation of new labour markets has arisen discussions on the contents GIS training in various centres of higher education, e.g. in the Netherlands, the US, and those have been similar to the ones presented in this article (Toppen F. J. 1992) and some issues needed to be resolved in court (DiBiase, D. 2008). You can see how important these meetings of educators are for exchanging opinions and experience. They have allowed to meed people representing various fi elds involved in the geoinformation, which may result in co-operation and new educational initiatives, and sometimes, competition. Finally, we should agree with prof. J. Gaździcki (2009 p. 12) that “It is obvious that the success of any measures to modernise education in the area under consideration depends on the interest of academic communities, involvement of research and academic staff in these endeavours, their will, ambition and willingness to co-operate”.This book has been prepared within the project „Geographic Information Systems (GIS) – the integration of environmental and climate issues as an important factor of economic development and quality of life – an innovative second-degree studies” supported by a grant from Norway through the Norway Grants and co-financed by the Polish funds. (Agreement No FSS/2014/HEI/W/0114/U/0013)

Rapid Static Positioning Using a Four System GNSS Receivers in the Forest Environment

Global Navigation Satellite Systems (GNSS) are crucial elements used in forest inventories. Forest metrics modeling efficacy depends on the accuracy of determining sample plot locations by GNSS. As of 2021, the GNSS consists of 120 active satellites, ostensibly improving position acquisition in forest conditions. The main idea of this article was to evaluate GIS-class and geodetic class GNSS receivers on 33 control points located in the forest. The main assumptions were operating on four GNSS systems (GPS, GLONASS, Galileo, and BeiDou), keeping a continuous online connection to the network of reference stations, maintaining occupation time-limited to 60 epochs, and repeating all the measurements three times. Rapid static positioning was tested, as it compares the true performance of the four GNSS systems receivers. Statistical differences between the receivers were confirmed. The GIS-class receiver achieved an accuracy of 1.38 m and a precision of 1.29 m, while the geodetic class receiver reached 0.74 m and 0.91 m respectively. Even though the research was conducted under the same data capture conditions, the large variability of positioning results were found to be caused by cycle slips and the multipath effect

Modeling light conditions on the forest floor

Contemporary models of light conditions on the forest floor can be divided into two categories: undercanopy models that allow the light conditions in a stand under the canopy to be simulated, and models that take into account shielding from the side. Under-canopy models precisely estimate the availability of wavelengths of light spatially distributed under the canopy of stands: however these models require a large amount of data on the spatial structure of forest stands. The other class of models describes the light conditions on a particular open surface. These incorporate shielding from the side and are easier to use as they require less data than under-canopy models. In practice, in forest conditions, such models require data on the size, shape, and geographical location of surveyed surfaces (e.g. gaps, and cut areas) and on the height of the surrounding stand. Often, these data are available in databases, such as the State Forest Information System (SILP), can otherwise be obtained relatively easily (and inexpensively). Compared to under-canopy models, these models provide a cheap way to obtain useful information on variation in the light environment that affects the microclimate for regenerating plants on clearcuts and canopy gaps

Wykorzystanie numerycznego modelu terenu (NMT) w analizie zróżnicowania facjalnego osadów wezbraniowych Wisły między Basonią a Solcem nad Wisłą oraz jego znaczenia dla koncentracji metali ciężkich

Celem pracy było określenie przydatności cyfrowego modelu terenu (NMT) do identyfikacji zróżnicowania środowisk depozycji współczesnych utworów wezbraniowych, a także określenie związku między poszczególnymi strefami morfodynamicznymi równi zalewowej a koncentracją metali ciężkich w osadach powierzchniowych. Badania prowadzono na odcinku doliny środkowej Wisły w obrębie jej Małopolskiego Przełomu. Poszczególne strefy morfodynamiczne były identyfikowane z wykorzystaniem analizy numerycznego modelu terenu o rozdzielczości 10 m oraz na podstawie wyników badań terenowych. Położenie granic wychodni i form rzeźby równi zalewowej określono w terenie, wykorzystując odbiorniki kodowe DGPS. W trakcie badań pobrano 110 próbek osadów wezbraniowych. Charakterystyka litologiczna obejmowała analizę granulometryczną, oznaczenie zawartości CaCO3, składu mineralnego frakcji iłowej, a także zawartości substancji organicznej. Badano zawartość Cu, Pb, Zn, Ni, Co, Cr, Sr, Cd i V oraz stosunek Fe do Al. Wyniki oznaczeń laboratoryjnych poddane zostały analizie statystycznej. Otrzymane zróżnicowanie zawartości metali ciężkich w osadach wezbraniowych koresponduje z wydzielonymi dziewięcioma typami form rzeźby równi zalewowej Wisły

Impacts of forest spatial structure on variation of the multipath phenomenon of navigation satellite signals

The GNSS (Global Navigation Satellite System) receivers are commonly used in forest management in order to determine objects coordinates, area or length assessment and many other tasks which need accurate positioning. Unfortunately, the forest structure strongly limits access to satellite signals, which makes the positioning accuracy much weak comparing to the open areas. The main reason for this issue is the multipath phenomenon of satellite signal. It causes radio waves reflections from surrounding obstacles so the signal do not reach directly to the GNSS receiver’s antenna. Around 50% of error in GNSS positioning in the forest is because of multipath effect. In this research study, an attempt was made to quantify the forest stand features that may influence the multipath variability. The ground truth data was collected in six Forest Districts located in different part of Poland. The total amount of data was processed for over 2,700 study inventory plots with performed GNSS measurements. On every plot over 25 forest metrics were calculated and over 25 minutes of raw GNSS observations (1500 epochs) were captured. The main goal of this study was to find the way of multipath quantification and search the relationship between multipath variability and forest structure. It was reported that forest stand merchantable volume is the most important factor which influence the multipath phenomenon. Even though the similar geodetic class GNSS receivers were used it was observed significant difference of multipath values in similar conditions

Impacts of forest spatial structure on variation of the multipath phenomenon of navigation satellite signals

The GNSS (Global Navigation Satellite System) receivers are commonly used in forest management in order to determine objects coordinates, area or length assessment and many other tasks which need accurate positioning. Unfortunately, the forest structure strongly limits access to satellite signals, which makes the positioning accuracy much weak comparing to the open areas. The main reason for this issue is the multipath phenomenon of satellite signal. It causes radio waves reflections from surrounding obstacles so the signal do not reach directly to the GNSS receiver’s antenna. Around 50% of error in GNSS positioning in the forest is because of multipath effect. In this research study, an attempt was made to quantify the forest stand features that may influence the multipath variability. The ground truth data was collected in six Forest Districts located in different part of Poland. The total amount of data was processed for over 2,700 study inventory plots with performed GNSS measurements. On every plot over 25 forest metrics were calculated and over 25 minutes of raw GNSS observations (1500 epochs) were captured. The main goal of this study was to find the way of multipath quantification and search the relationship between multipath variability and forest structure. It was reported that forest stand merchantable volume is the most important factor which influence the multipath phenomenon. Even though the similar geodetic class GNSS receivers were used it was observed significant difference of multipath values in similar conditions