Thomas Blaschke

Bio: Thomas Blaschke is an academic researcher from University of Salzburg. The author has contributed to research in topics: Landslide & Geographic information system. The author has an hindex of 56, co-authored 348 publications receiving 17021 citations. Previous affiliations of Thomas Blaschke include Goethe University Frankfurt & Research Studios Austria.

Object based image analysis for remote sensing

Abstract: Remote sensing imagery needs to be converted into tangible information which can be utilised in conjunction with other data sets, often within widely used Geographic Information Systems (GIS). As long as pixel sizes remained typically coarser than, or at the best, similar in size to the objects of interest, emphasis was placed on per-pixel analysis, or even sub-pixel analysis for this conversion, but with increasing spatial resolutions alternative paths have been followed, aimed at deriving objects that are made up of several pixels. This paper gives an overview of the development of object based methods, which aim to delineate readily usable objects from imagery while at the same time combining image processing and GIS functionalities in order to utilize spectral and contextual information in an integrative way. The most common approach used for building objects is image segmentation, which dates back to the 1970s. Around the year 2000 GIS and image processing started to grow together rapidly through object based image analysis (OBIA - or GEOBIA for geospatial object based image analysis). In contrast to typical Landsat resolutions, high resolution images support several scales within their images. Through a comprehensive literature review several thousand abstracts have been screened, and more than 820 OBIA-related articles comprising 145 journal papers, 84 book chapters and nearly 600 conference papers, are analysed in detail. It becomes evident that the first years of the OBIA/GEOBIA developments were characterised by the dominance of ‘grey’ literature, but that the number of peer-reviewed journal articles has increased sharply over the last four to five years. The pixel paradigm is beginning to show cracks and the OBIA methods are making considerable progress towards a spatially explicit information extraction workflow, such as is required for spatial planning as well as for many monitoring programmes.

Geographic Object-Based Image Analysis - Towards a new paradigm.

Abstract: The amount of scientific literature on (Geographic) Object-based Image Analysis – GEOBIA has been and still is sharply increasing. These approaches to analysing imagery have antecedents in earlier research on image segmentation and use GIS-like spatial analysis within classification and feature extraction approaches. This article investigates these development and its implications and asks whether or not this is a new paradigm in remote sensing and Geographic Information Science (GIScience). We first discuss several limitations of prevailing per-pixel methods when applied to high resolution images. Then we explore the paradigm concept developed by Kuhn (1962) and discuss whether GEOBIA can be regarded as a paradigm according to this definition. We crystallize core concepts of GEOBIA, including the role of objects, of ontologies and the multiplicity of scales and we discuss how these conceptual developments support important methods in remote sensing such as change detection and accuracy assessment. The ramifications of the different theoretical foundations between the ‘per-pixel paradigm’ and GEOBIA are analysed, as are some of the challenges along this path from pixels, to objects, to geo-intelligence. Based on several paradigm indications as defined by Kuhn and based on an analysis of peer-reviewed scientific literature we conclude that GEOBIA is a new and evolving paradigm.

What’s wrong with pixels? Some recent developments interfacing remote sensing and GIS

Abstract: While remote sensing made enormous progress over the last years in terms of improved resolution, data availability and public awareness, a vast majority of applications rely on basic image processing concepts developed in the 70s: per-pixel classification of in a multi-dimensional feature space. It is argued that this methodology does not make use of any spatial concepts. Especially in high-resolution images it is very likely that neighbouring pixels belong to the same land cover class as the pixel under consideration. The authors argue for classification of homogeneous groups of pixels reflecting our objects of interest in reality and use algorithms to delineate objects based on contextual information in an image on the basis of texture or fractal dimension. ZUSAMMENFASSUNG Was ist mit den Pixeln los? Neue Entwicklungen zur Integration von Fernerkundung und GIS. Fernerkundung hat sich in den vergangenen Jahren bezüglich Bildauflösung, Datenverfügbarkeit und öffentlicher Präsenz enorm weiterentwickelt, trotzdem basieren nahezu alle Anwendungen auf den methodischen Grundlagen der Bildverarbeitung aus den 70er Jahren: individuelle Pixel werden im mehrdimensionalen Spektralraum klassifiziert, ohne irgendwelche räumlichen Konzepte zu berücksichtigen. Insbesondere bei hochauflösenden Bildern gehören benachbarte Pixel mit hoher Wahrscheinlichkeit zur selben Kategorie wie das aktuelle Pixel. Die Autoren argumentieren für Klassifikationsansätze homogener Gruppen von Pixeln, die realweltlichen Objekten entsprechen und aus kontextueller Bildinformation (Textur, fraktale Dimension) abgeleitet werden. Dr. Thomas Blaschke 1 Patterns do matter, or: the need for change We start our considerations of recent remote sensing practice from the user’s point of view and, more precisely, from a geographical or landscape ecology point of view: The world in its complexity and manifold relationships cannot easily be grasped in full depth. Creating models of the world or computer-based representations of its surface poses a series of problems. In landscape ecology, there is a growing awareness about continuity of phenomena and discontinuities of scales. Forman (1995) described this ambiguity through the metaphor of a person gradually descending with a spaceship or balloon. Human perception abruptly starts to discover patterns and mosaics. Many mosaics are quasi-stable or persistent for a while, separated by rapid changes that represent the “domains of scale”. Each domain exhibits certain spatial patterns, which in turn are produced by a certain causal mechanism or group of processes. Back to remote sensing: The ultimate goal is to mirror, elucidate, quantify and to describe surface patterns in order to contribute to an understanding of the underlying phenomena and processes. Since the start of the first Landsat satellite in 1972, we achieve this in more or less the same way: We measure some reflectance at the Earth’s surface. The smallest unit is called a ‘pixel’. In this paper, we do not question the pixel as an important and necessary entity. Instead, we argue for a somewhat different handling of our entities introducing the concepts of neighbourhood, distance and location. All these concepts are not new. In fact, entire disciplines like Geography are based on these conINTERFACING REMOTE SENSING AND GIS

The Theory of Island Biogeography

Abstract: Preface to the Princeton Landmarks in Biology Edition vii Preface xi Symbols Used xiii 1. The Importance of Islands 3 2. Area and Number of Speicies 8 3. Further Explanations of the Area-Diversity Pattern 19 4. The Strategy of Colonization 68 5. Invasibility and the Variable Niche 94 6. Stepping Stones and Biotic Exchange 123 7. Evolutionary Changes Following Colonization 145 8. Prospect 181 Glossary 185 References 193 Index 201

Principles of Neural Science

Abstract: I have developed "tennis elbow" from lugging this book around the past four weeks, but it is worth the pain, the effort, and the aspirin. It is also worth the (relatively speaking) bargain price. Including appendixes, this book contains 894 pages of text. The entire panorama of the neural sciences is surveyed and examined, and it is comprehensive in its scope, from genomes to social behaviors. The editors explicitly state that the book is designed as "an introductory text for students of biology, behavior, and medicine," but it is hard to imagine any audience, interested in any fragment of neuroscience at any level of sophistication, that would not enjoy this book. The editors have done a masterful job of weaving together the biologic, the behavioral, and the clinical sciences into a single tapestry in which everyone from the molecular biologist to the practicing psychiatrist can find and appreciate his or

The Production of Space

Abstract: ‘The Production of Space’, in: Frans Jacobi, Imagine, Space Poetry, Copenhagen, 1996, unpaginated.

Object based image analysis for remote sensing

Abstract: Remote sensing imagery needs to be converted into tangible information which can be utilised in conjunction with other data sets, often within widely used Geographic Information Systems (GIS). As long as pixel sizes remained typically coarser than, or at the best, similar in size to the objects of interest, emphasis was placed on per-pixel analysis, or even sub-pixel analysis for this conversion, but with increasing spatial resolutions alternative paths have been followed, aimed at deriving objects that are made up of several pixels. This paper gives an overview of the development of object based methods, which aim to delineate readily usable objects from imagery while at the same time combining image processing and GIS functionalities in order to utilize spectral and contextual information in an integrative way. The most common approach used for building objects is image segmentation, which dates back to the 1970s. Around the year 2000 GIS and image processing started to grow together rapidly through object based image analysis (OBIA - or GEOBIA for geospatial object based image analysis). In contrast to typical Landsat resolutions, high resolution images support several scales within their images. Through a comprehensive literature review several thousand abstracts have been screened, and more than 820 OBIA-related articles comprising 145 journal papers, 84 book chapters and nearly 600 conference papers, are analysed in detail. It becomes evident that the first years of the OBIA/GEOBIA developments were characterised by the dominance of ‘grey’ literature, but that the number of peer-reviewed journal articles has increased sharply over the last four to five years. The pixel paradigm is beginning to show cracks and the OBIA methods are making considerable progress towards a spatially explicit information extraction workflow, such as is required for spatial planning as well as for many monitoring programmes.