Kinkeldey C.,HafenCity University Hamburg
ISPRS International Journal of Geo-Information | Year: 2014
Analysis of land cover change is one of the major challenges in the remote sensing and GIS domain, especially when multi-temporal or multi-sensor analyses are conducted. One of the reasons is that errors and inaccuracies from multiple datasets (for instance caused by sensor bias or spatial misregistration) accumulate and can lead to a high amount of erroneous change. A promising approach to counter this challenge is to quantify and visualize uncertainty, i.e., to deal with imperfection instead of ignoring it. Currently, in GIS the incorporation of uncertainty into change analysis is not easily possible. We present a concept for uncertainty-aware change analysis using a geovisual analytics (GVA) approach. It is based on two main elements: first, closer integration of change detection and analysis steps; and second, visual communication of uncertainty during analysis. Potential benefits include better-informed change analysis, support for choosing change detection parameters and reduction of erroneous change by filtering. In a case study with a change scenario in an area near Hamburg, Germany, we demonstrate how erroneous change can be filtered out using uncertainty. For this, we implemented a software prototype according to the concept presented. We discuss the potential and limitations of the concept and provide recommendations for future work. © 2014 by the authors; licensee MDPI, Basel, Switzerland.
Stephenson U.M.,HafenCity University Hamburg
Acta Acustica united with Acustica | Year: 2010
In room acoustics as well as in noise immission prognosis, ray tracing methods are efficient and widely used. Nevertheless, as is well recognised, these energetic methods assuming incoherent superposition fail when diffraction becomes important. The aim is to solve this main deficiency, but the energetic model shall be retained. However, since random emitted particles never pass edges exactly, analytical edge diffraction approaches may not be applied. These and other general problems of combining diffractions with the numerical methods of geometrical room acoustics are discussed in the first part of the paper. To introduce diffraction but preserve the algorithmic advantage of ray tracing, the author had proposed a sound particle diffraction model based on Heisenbergs uncertainty relation (UR) introducing the concept of a 'diffraction angle probability' and an 'edge diffraction strength' (the closer the by-pass-distance the stronger the diffraction effect'). This model, already presented in 1986, demonstrated very good agreements with the expected transfer functions of the basic reference cases of a half-infinite screen and a slit in far field. It has now for the first time been embedded in a full ray tracing program enabling also finite source and receiver distances. The results have also been compared with the exact wave-theoretical results of Svenssonts secondary edge source model. For most cases of the screen and the slit the agreements are very good (less than 1 dB). Also - not self evident - the reciprocity principle seems fulfilled. Exploiting the UR seems to be a useful approach not only for light - as has been published in the field of optical ray tracing - but also for sound. However, whether the method works also with higher order diffraction and with other structures has not yet been investigated for sound. A very difficult practical problem remains the explosion of computing time which may be solved by the re-unification -algorithm provided by Quantized Pyramidal Beam Tracing. © S. Hirzel Verlag.
Poplin A.,HafenCity University Hamburg
Computers, Environment and Urban Systems | Year: 2012
The aim of this paper is to study the implementation of online games to encourage public participation in urban planning. Its theoretical foundations are based on previous work in public participatory geographical information systems (PP GISs), play and games, with a special focus on serious games. Serious games aim to support learning processes in a new, more playful way. We developed the concept of playful public participation in urban planning, including playful elements such as storytelling, walking and moving, sketching, drawing, and games. A group of students designed an online serious public participatory game entitled NextCampus. The case study used in NextCampus was taken from the real-world question of a possible move of a university campus to a new location in the city of Hamburg, Germany. The development of the serious public participatory game NextCampus resulted in a physical prototype, user interface design, and a computational model of the game. The NextCampus game was tested with the help of two groups of urban planning students and presented to three external experts who provided valuable recommendations for further development. The critical comments questioned the level of complexity involved in such games. The positive comments included recognition of the potential for joy and the playfulness a game like NextCampus could evoke. © 2011 Elsevier Ltd.
Kinkeldey C.,HafenCity University Hamburg
International Journal of Geographical Information Science | Year: 2014
Analyses of spatiotemporal data are affected by different kinds of uncertainty, and various studies have shown that their impact can be severe. This is especially true for land cover change analysis based on remotely sensed data – it has been shown that ignoring uncertainty can lead to unreliable results. Approaches are needed that incorporate information on uncertainty into the analysis. However, usable models and methods are still rare and the supposed positive effect of uncertainty information has not been extensively studied. In this contribution, we describe the development of ICchange, an interactive visual prototype for the exploratory analysis of land cover change following a geovisual analytics approach. Apart from serving as proof of concept, the prototype will be used to evaluate the role of uncertainty information during change analyses. We conducted a qualitative evaluation of the prototype using low-level tasks to test basic usability. The input from the study is used to improve the design. A special focus is placed on the visual representation of uncertainty in one of the views that did not perform satisfyingly. The prototype presented here will be used in future studies to evaluate the role of uncertainty in real-world change analysis. © 2014, © 2014 Taylor & Francis.
Roetzel A.,Deakin University |
Tsangrassoulis A.,University of Thessaly |
Dietrich U.,HafenCity University Hamburg
Building and Environment | Year: 2014
The building sector has a significant share in a county's total greenhouse gas emissions, and as a reaction to the Kyoto commitment most countries are constantly adjusting building energy requirements in order to reduce greenhouse gas emissions and mitigate the climate change. While it is easier to set standards for the building fabric and for technical systems, the impact of occupants on comfort and energy performance in buildings has proven to be important, but is a lot harder to account for. This paper therefore aims to investigate the magnitude of influence of occupants in relation to climate and architectural design on thermal comfort and CO2 emissions in offices in different climate zones of the world. The aim is to identify typical patterns and key parameters for optimisation.For this purpose, a parametric study for a typical cellular office room has been conducted using the simulation software EnergyPlus. Two different occupant scenarios are each compared with three different architectural design variations and modelled in the context of three different locations for the IPCC climate change scenario A2 for 2030. The evaluation of the results is focused on two different modes of operation. For natural ventilation adaptive thermal comfort according to ASHRAE Standard 55 has been evaluated, and for mixed mode operation final energy consumption and resulting CO2 emissions. The results indicate a first approach to estimate comfort levels based on climatic data, architectural design priorities and occupancy. Additionally, warmer climates seem to have larger optimisation potential for comfort and energy performance in offices compared to colder climates. © 2013 Elsevier Ltd.