WebGIS: Anwendungen über ArcGIS Server in der Kantonalen Verwaltung Luzern

Eine immer größere Zahl von Mitarbeitern öffentlicher Verwaltungen arbeitet direkt oder indirekt mit Geodaten. Nicht alle sind Spezialisten im Umgang mit GIS Software. ArcGIS Server bietet mit einem umfangreichen Framework die Möglichkeit, angepasste GIS Anwendungen zu entwickeln, den Funktionsumfang auf benötigte Funktionen zu reduzieren und komplexe Arbeitsabläufe zu optimieren. Die Abteilung Geoinformation und Vermessung des Kantons Luzern entwickelt seit dem Jahr 2006 in Zusammenarbeit mit der Universität Bern ArcGIS Server-basierte Webanwendungen für verschiedene Abteilungen der kantonalen Verwaltung. In dieser Zeit sind mehrere Anwendungen entstanden, darunter eine Webapplikation für die effiziente Erfassung, Beurteilung und Verwaltung von Waldeingriffsflächen (Waldportal), für die dynamische Abgrenzung und Auswertung von Einzugsgebieten, sowie für das Betrachten von aufgezeichneten Videos von Kantonsstraßenabschnitten. In der Präsentation werden die genannten Applikationen vorgestellt und Hintergründe der Entwicklung sowie der Architektur besprochen.

A comparison of pixel and object-based land cover classification. A case study of the Asmara region, Eritrea

In this paper we compare the performance of two image classification paradigms (object- and pixel-based) for creating a land cover map of Asmara, the capital of Eritrea and its surrounding areas using a Landsat ETM+ imagery acquired in January 2000. The image classification methods used were maximum likelihood for the pixel-based approach and Bhattacharyya distance for the object-oriented approach available in, respectively, ArcGIS and SPRING software packages. Advantages and limitations of both approaches are presented and discussed. Classifications outputs were assessed using overall accuracy and Kappa indices. Pixel- and object-based classification methods result in an overall accuracy of 78% and 85%, respectively. The Kappa coefficient for pixel- and object-based approaches was 0.74 and 0.82, respectively. Although pixel-based approach is the most commonly used method, assessment and visual interpretation of the results clearly reveal that the object-oriented approach has advantages for this specific case-study.

Capacity Building in Geoprocessing

Manual used for the implementation of CDE's Geoprocessing courses in the South and East. Composed of 6 modules covering important aspects of GIS handling and implementation: 1) Introduction to GIS; 2) Management issues; 3) GIS data preparation; 4) GIS data presentation; 5) Vector data analysis; 6) Raster data analysis. At the moment the manual is designed for use with ArcGIS. Work on a manual for use with open source software is currently ongoing. This manual was successfully used during several GIS training events in Kenya and Tajikistan.

An automated method for mapping physical soil and water conservation structures on cultivated land using GIS and remote sensing techniques

An efficient and reliable automated model that can map physical Soil and Water Conservation (SWC) structures on cultivated land was developed using very high spatial resolution imagery obtained from Google Earth and ArcGIS, ERDAS IMAGINE, and SDC Morphology Toolbox for MATLAB and statistical techniques. The model was developed using the following procedures: (1) a high-pass spatial filter algorithm was applied to detect linear features, (2) morphological processing was used to remove unwanted linear features, (3) the raster format was vectorized, (4) the vectorized linear features were split per hectare (ha) and each line was then classified according to its compass direction, and (5) the sum of all vector lengths per class of direction per ha was calculated. Finally, the direction class with the greatest length was selected from each ha to predict the physical SWC structures. The model was calibrated and validated on the Ethiopian Highlands. The model correctly mapped 80% of the existing structures. The developed model was then tested at different sites with different topography. The results show that the developed model is feasible for automated mapping of physical SWC structures. Therefore, the model is useful for predicting and mapping physical SWC structures areas across diverse areas.

Size-frequency distribution of boulders ≥7 m on comet 67P/Churyumov-Gerasimenko

Aims. We derive for the first time the size-frequency distribution of boulders on a comet, 67P/Churyumov-Gerasimenko (67P), computed from the images taken by the Rosetta/OSIRIS imaging system. We highlight the possible physical processes that lead to these boulder size distributions. Methods. We used images acquired by the OSIRIS Narrow Angle Camera, NAC, on 5 and 6 August 2014. The scale of these images (2.44−2.03 m/px) is such that boulders ≥7 m can be identified and manually extracted from the datasets with the software ArcGIS. We derived both global and localized size-frequency distributions. The three-pixel sampling detection, coupled with the favorable shadowing of the surface (observation phase angle ranging from 48° to 53°), enables unequivocally detecting boulders scattered all over the illuminated side of 67P. Results. We identify 3546 boulders larger than 7 m on the imaged surface (36.4 km2), with a global number density of nearly 100/km2 and a cumulative size-frequency distribution represented by a power-law with index of −3.6 +0.2/−0.3. The two lobes of 67P appear to have slightly different distributions, with an index of −3.5 +0.2/−0.3 for the main lobe (body) and −4.0 +0.3/−0.2 for the small lobe (head). The steeper distribution of the small lobe might be due to a more pervasive fracturing. The difference of the distribution for the connecting region (neck) is much more significant, with an index value of −2.2 +0.2/−0.2. We propose that the boulder field located in the neck area is the result of blocks falling from the contiguous Hathor cliff. The lower slope of the size-frequency distribution we see today in the neck area might be due to the concurrent processes acting on the smallest boulders, such as i) disintegration or fragmentation and vanishing through sublimation; ii) uplifting by gas drag and consequent redistribution; and iii) burial beneath a debris blanket. We also derived the cumulative size-frequency distribution per km2 of localized areas on 67P. By comparing the cumulative size-frequency distributions of similar geomorphological settings, we derived similar power-law index values. This suggests that despite the selected locations on different and often opposite sides of the comet, similar sublimation or activity processes, pit formation or collapses, as well as thermal stresses or fracturing events occurred on multiple areas of the comet, shaping its surface into the appearance we see today.