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Examples of object-oriented classification performed on high-resolution satellite images

100%

Lewiński S., Zaremski K., Kwiatkowska J. M.

Miscellanea Geographica. Regional Studies on Development

2004

vol. 11

349-358

Information about the types of land cover and its use is obtained by the visual interpretation of the color composite of satellite images or by the use of automatic classification algorithms. For obvious reasons, the automatic classification methods make it possible to obtain information quicker and much faster than the traditional interpretation method. The commonly used automatic methods of satellite image classification, based on supervised or unsupervised classification algorithms, are the most accurate when used with low resolution images. In the case of images with 1-meter-sized pixels, showing a diversity of land cover forms, it is not possible to obtain satisfactory results. New classification techniques, based on object-oriented classification algorithms, have been developing for a couple of years now. In contrast to the traditional methods, the new operating procedure does not involve the classification of single pixels, but of entire objects, into which the content of the satellite image is divided. Aside from the spectral values of the pixels, the shape of the objects created by the pixels and the relationships between the objects, are also considered during the analysis. Similar to visual interpretation, variation in the texture of the image can also be taken into account in this case. The aim of this article is to present the possibility of using high density satellite images in object-oriented classification. The classification presented is that of a high-rise built area in Wrocław and of bridges on the Vistula River in Warsaw.

Rozwój badań nad klimatem lokalnym Krakowa

51%

Bokwa A.

Acta Geographica Lodziensia

2019

vol. 108

7-20

Badania nad klimatem lokalnym Krakowa, realizowane po II wojnie światowej, opierały się na obserwacjach i pomiarach stacjonarnych na stacjach meteorologicznych i w punktach pomiarowych działających okresowo, na pomiarach mobilnych, a także na analizie danych sodarowych i satelitarnych. Zróżnicowana rzeźba terenu jest równie ważnym czynnikiem kształtującym klimat lokalny Krakowa jak użytkowanie/pokrycie terenu. Miejską wyspę ciepła należy rozpatrywać jako element struktury termicznej obszaru miasta i okolic w mezoskali, z uwzględnieniem inwersji temperatury powietrza i asymetrii termicznej doliny Wisły w Krakowie i okolicy. Pole opadów atmosferycznych jest znacząco zróżnicowane, głównie wskutek urozmaiconej rzeźby terenu. Sumy roczne opadu są wyższe w mieście niż poza miastem o ok. 80 mm, wyższa jest także liczba dni z opadem, ale dotyczy to tylko dni z sumą dobową poniżej 5 mm. Położenie Krakowa w dolinie Wisły i osłonięcie wypu-kłymi formami terenu od południa, północy i zachodu powoduje, że naturalna wentylacja pozioma i pionowa jest zła, co przyczynia się do częstego występowania ponadnormatywnych stężeń zanieczyszczeń powietrza. Średnia roczna prędkość wiatru w centrum miasta wynosi 1,8 m•s–1, a częstość cisz atmosferycznych sięga 30%.

Studies on local climate of Kraków conducted after the Second World War were based on observations and measurements at regular meteorological stations and at short-term measurement points, as well as on mobile measurements and analyses of sodar and satellite data. The diversified landform and the land use/land cover are equally important factors controlling the local climate of Kraków. The urban heat island should be studied as an element of the thermal structure of the city, in the mesoscale, including the impact of air temperature inversions and thermal asymmetry of the Vistula river valley in Kraków. Atmospheric precipitation is highly differentiated spatially due to the impact of relief. The annual totals are higher in the city than in the surrounding areas by about 80 mm; the number of days with precipitation is also greater but the latter is true only for daily totals below 5 mm. The location of Kraków in the Vistula river valley and the sheltering effect of the convex landforms to be found south, north and west of the city are the reason for poor natural horizontal and vertical ventilation, which in turn often generates air pollution concentrations above the acceptable levels. The mean annual wind speed in the city centre is 1.8 m•s–1, and the frequency of atmospheric calm reaches 30%.

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Examples of object-oriented classification performed on high-resolution satellite images

Rozwój badań nad klimatem lokalnym Krakowa