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Ways of improving the accuracy of digital aerial photography by the railway transport inventoy

Dorozhynskyy O., Dychko L.

Geomatics, Landmanagement and Landscape

2014

no. 2

19--30

The development of railway sector around the world has always been a vital issue, as it plays important social, financial and economical role and influences the development of the country a lot. Because of constant growth and modernizing of the railway sector all processes and items of land and property fund have to be monitored. On the basis of the world experience, trends in the development of methods and technologies of area mapping it has been established that for the inventory of land and property fund objects cartographic material at 1 : 500 or 1 : 1000 scales suits the most. With the large amounts of work (for example area of mapping and number of railroad objects) it is reasonable to use digital aerial photography and technology of digital data processing, in particular methods of digital photogrammetry. In order to increase the accuracy of creating the cartographic component, the authors suggest, when choosing the parameters of aerial photography, taking into account spatial resolution of camera system, its geometrical properties, the influence of external factors and first of all the atmospheric refraction. It has been proved that by highly precise aerial photography the accuracy of fixation of angular elements of camera orientation with the help of Inertial Navigation Systems (INS) may be insufficient. Therefore it is recommended to thicken core network using block phototriangulation. This paper presents the description and results of experimental work, which helped to create cartographic material from digital images at 1 : 3000 scale with an accuracy of 4–5 cm, which fully meets the requirements for holding inventory, monitoring, maintenance, design and construction.The development of railway sector around the world has always been a vital issue, as it plays important social, financial and economical role and influences the development of the country a lot. Because of constant growth and modernizing of the railway sector all processes and items of land and property fund have to be monitored. On the basis of the world experience, trends in the development of methods and technologies of area mapping it has been established that for the inventory of land and property fund objects cartographic material at 1 : 500 or 1 : 1000 scales suits the most. With the large amounts of work (for example area of mapping and number of railroad objects) it is reasonable to use digital aerial photography and technology of digital data processing, in particular methods of digital photogrammetry. In order to increase the accuracy of creating the cartographic component, the authors suggest, when choosing the parameters of aerial photography, taking into account spatial resolution of camera system, its geometrical properties, the influence of external factors and first of all the atmospheric refraction. It has been proved that by highly precise aerial photography the accuracy of fixation of angular elements of camera orientation with the help of Inertial Navigation Systems (INS) may be insufficient. Therefore it is recommended to thicken core network using block phototriangulation. This paper presents the description and results of experimental work, which helped to create cartographic material from digital images at 1 : 3000 scale with an accuracy of 4–5 cm, which fully meets the requirements for holding inventory, monitoring, maintenance, design and construction.

Aspekty dokładności generowania NMT na podstawie obrazów z cyfrowej kamery ADS40

Ewiak I., Karwel K., Kraszewski B.

Archiwum Fotogrametrii, Kartografii i Teledetekcji

2008

Vol. 18a

111--119

W artykule zaprezentowano analizę porównawczą dokładności generowania numerycznego modelu terenu (NMT) w oparciu o dane pozyskane skanerową lotniczą kamerą cyfrową ADS40 i przetworzone przy udziale różnych systemów fotogrametrycznych. Prace prowadzone były w Zakładzie Fotogrametrii, Instytutu Geodezji i Kartografii w ramach realizacji projektu badawczego finansowanego przez Ministerstwo Nauki i Szkolnictwa Wyższego w latach 2007-2009, którego jednym z głównych celów jest określenie metodyki opracowania NMT z trzylinijkowej lotniczej kamery cyfrowej. W niniejszym artykule opisano metodykę generowania numerycznego modelu terenu na podstawie stereoskopowych zobrazowań z cyfrowej kamery lotniczej ADS40. Do badań wykorzystano blok fotogrametryczny składający się z trzech szeregów zdjęć, z których każde pozyskane było w kanale panchromatycznym w sekwencji przód-wstecz oraz w kanale czerwonym w nadirze. Do opracowania danych źródłowych wykorzystano moduły programów Image Station firmy Intergraph, DTM Box firmy Inpho oraz Leica Photogrammetry Suite firmy ERDAS. Do analizy porównawczej wykorzystano NMT wygenerowane na podstawie sekwencji zorientowanych zewnętrznie zobrazowań ADS40 z uwzględnieniem elementów pomiaru GPS oraz IMU, a także pomiaru dodatkowych punktów wiążących. Do oceny dokładności NMT wykorzystano dane referencyjne w postaci profili kontrolnych pomierzonych w terenie techniką GPS. W wyniku przeprowadzonych badań stwierdzono, że dokładność automatycznego generowania NMT na podstawie zobrazowań z trzylinijkowej kamery ADS40 waha się w przedziale od 0.13 m do 1.42 m. Dokładność ta zależy głównie od kanałów spektralnych zobrazowań użytych w procesie pomiaru korelacyjnego, kąta obrazującego linijki detektora oraz użytego systemu pomiarowego. Na podstawie analiz dokładnościowych potwierdzono, że najlepsze wyniki uzyskano dla NMT wygenerowanych przy wykorzystaniu obrazów ADS40 pozyskanych przy stosunku bazowym modelu stereoskopowego bliskim 0.8.

The paper discusses a comparative analysis of accuracy in generation of the digital elevation model (DEM) on the basis of ADS40 data processed by different photogrammetric systems. The research, supported by the Ministry of Science and Higher Education, was carried out in 2007- 2009 at the Photogrammetry Department of the Institute of Geodesy and Cartography. One of the main aims of the project was to develop a methodology for measuring DEM based on ADS40 images. The research made use of the photogrammetric block containing three strips of images, each taken in the panchromatic mode in sequence forward and backward, and in the red range of the visible band in the nadir. The source data were procured by using modules of the Image Station Intergraph, DTM Box Inpho and the Leica Photogrammetry Suite ERDAS software. The DEMs generated based on a sequence of ADS40 images and their absolute orientation elements estimated with GPS and IMU measurement as well as additional pass and tie points were used in the comparative analysis. To estimate the accuracy of DEM, reference data in the form of terrain profiles measured by GPS were used as well. The analyses allowed to conclude that the accuracy of automatic measurement of DEM altitude points, based on different combinations of ADS40 images, ranges between 0.13 and 1.42 m. The accuracy depends mainly on the spectral resolution of images used in correlative measurement, in viewing the detector line angle , and on the measuring system used. The DEM accuracy analyses demonstrated the best results of autocorrelation measurements to be obtained for the ADS40 stereoscopic model base ratio of 0.8.