A comparison of digital elevation models generated from different data sources

S. Rayburg, M. Thoms, M. Neave

10.1016/j.geomorph.2008.11.007

 

It can be challenging to accurately determine the topography of physically complex landscapes in remote areas. Ground-based surveys can be difficult, time consuming and may miss significant elements of the landscape. This study compares digital elevation models (DEMs) generated from three different data sources, of the physically complex Narran Lakes Ecosystem, a major floodplain wetland ecosystem in Australia. Topographic surfaces were generated from an airborne laser altimetry (LiDAR) survey, a ground-based differential GPS (DGPS) survey containing more than 20,000 points, and the 9″ DEM of Australia. The LiDARand DGPS-derived data generated a more thorough DEM than the 9″ DEM; however, LiDAR generated a surface topography that yielded significantly more detail than the DGPS survey, with no noticeable loss of elevational accuracy. Both the LiDAR- and the DGPS-derived DEMs compute the overall surface area and volume of the largest floodplain lake within the system to within 1% of each other. LiDAR is shown to be a highly accurate and robust technique for acquiring large quantities of topographic data, even in locations that are unsuitable for ground surveying and where the overall landscape is of exceptionally low relief. The results of this study highlight the potential for LiDAR surveys in the accurate determination of the topography of floodplain wetlands. These data can form an important component of water resource management decisions, particularly where environmental water allocations for these important ecosystems need to be determined.

 

A multi-resolution approach for filtering LiDAR altimetry data

J.L. Silván-Cárdenas, L. Wang

10.1016/j.isprsjprs.2006.06.002

 

Discrimination of above-ground objects from terrain has proven to be surprisingly difficult to automate in computers, especially for large areas of varied terrain characteristics. Several methods have been developed for filtering the LiDAR data, of which three approaches are more prevalent: linear prediction, slope based and morphological filtering. A common ground to all these approaches is that the range of scales at which feature variations exist tends to be smaller than the range of scales at which terrain variations exist. In this paper, a model-based approach is described in which multiscale gradient of the surface variation is computed and used to adaptively erode the gridded LiDAR data within a multi-resolution, analysis–synthesis framework, namely the multiscale Hermite transform (MHT). The method was tested over nineteen datasets, including urban and forest areas. An average coefficient of agreement was computed over all datasets and compared with that obtained from other methods. Results showed that the proposed method was within the top three among nine methods tested.

 

Ground Filtering Algorithms for Airborne LiDAR Data: A Review of Critical Issues

X. Meng, N. Currit, K. Zhao

10.3390/rs2030833

 

This paper reviews LiDAR ground filtering algorithms used in the process of creating Digital Elevation Models. We discuss critical issues for the development and application of LiDAR ground filtering algorithms, including filtering procedures for different feature types, and criteria for study site selection, accuracy assessment, and algorithm classification. This review highlights three feature types for which current ground filtering algorithms are suboptimal, and which can be improved upon in future studies: surfaces with rough terrain or discontinuous slope, dense forest areas that laser beams cannot penetrate, and regions with low vegetation that is often ignored by ground filters.

 

Segmentation of airborne laser scanning data using a slope adaptive neighborhood

S. Filin, N. Pfeifer

10.1016/j.isprsjprs.2005.10.005

 

This paper presents an algorithm for the segmentation of airborne laser scanning data. The segmentation is based on cluster analysis in a feature space. To improve the quality of the computed attributes, a recently proposed neighborhood system, called slope adaptive, is utilized. Key parameters of the laser data, e.g., point density, measurement accuracy, and horizontal and vertical point distribution, are used for defining the neighborhood among the measured points. Accounting for these parameters facilitates the computation of accurate and reliable attributes for the segmentation irrespective of point density and the 3D content of the data (step edges, layered surfaces, etc.) The segmentation with these attributes reveals more of the information that exists in the airborne laser scanning data.

 

Automated Extraction of Shorelines from Airborne Light Detection and Ranging Data and Accuracy  ssessment Based on Monte Carlo Simulation

H. Liu, D.Sherman, S. Gu

10.2112/05-0580.1

 

This research presents a segmentation-based, image processing method to automate the extraction of tidal datum referenced shorelines from airborne light detection and ranging (LIDAR) data. The method first segments a LIDAR digital elevation model (DEM) into a binary image, consisting of land and water pixels, by intersecting the LIDAR DEM and the tidal datum surface. A chain of image processing algorithms, including region grouping and labeling, two passes of image region scanning, a mathematical morphology operation, line tracing, and vectorization, is sequentially applied to the segmented binary image. Our applications to the upper Texas gulf coast show that the method is efficient, accurate, objective, and replicable. Spatially detailed shorelines can be derived from the LIDAR data with minimal human intervention. The method is a substantial technical improvement over standard cross-shore profile and contouring methods. We also examine and quantify the effects of vertical measurement error of the LIDAR system and the uncertainty in tidal datum determination on the shoreline extraction process using the Monte Carlo simulation technique. The Monte Carlo technique allows confidence intervals and summary error statistics to be calculated for each section of the extracted shoreline. Our analysis suggests that the horizontal position of the MHW shoreline derived from the LIDAR data is accurate within 4.5 m at the 95% confidence level.

 

Potential habitat connectivity of European bison (Bison bonasus) in the Carpathians

E. Ziółkowska, K. Ostapowicz, T. Kuemmerle, K. Perzanowski, V. C. Radeloff, J. Kozak

10.1016/j.biocon.2011.12.017

 

Habitat connectivity is important for the survival of species that occupy habitat patches too small to sustain an isolated population. A prominent example of such a species is the European bison (Bison bonasus), occurring only in small, isolated herds, and whose survival will depend on establishing larger, well-connected populations. Our goal here was to assess habitat connectivity of European bison in the Carpathians. We used an existing bison habitat suitability map and data on dispersal barriers to derive cost surfaces, representing the ability of bison to move across the landscape, and to delineate potential connections (as least-cost paths) between currently occupied and potential habitat patches. Graph theory tools were then employed to evaluate the connectivity of all potential habitat patches and their relative importance in the network. Our analysis showed that existing bison herds in Ukraine are isolated. However, we identified several groups of well-connected habitat patches in the Carpathians which could host a large population of European bison. Our analysis also located important dispersal corridors connecting existing herds, and several promising locations for future reintroductions (especially in the Eastern Carpathians) that should have a high priority for conservation efforts. In general, our approach indicates the most important elements within a landscape mosaic for providing and maintaining the overall connectivity of different habitat networks and thus offers a robust and powerful tool for conservation planning.

 

The Disappearance of the State from "Livable" Urban Spaces

K. B. Hankins, E.M. Powers

10.1111/j.1467-8330.2009.00699.x

 

This paper examines the absence of the state from the discourses and practices of "livable" urban spaces. Drawing from an ethnography of Atlantic Station, the USA's largest new urbanist infill development, we argue that "livable" urban spaces are increasingly arenas for luxury, theater, and consumption, and that the state, while an important actor in the creation of urban spaces such as Atlantic Station, has largely been made invisible. We see this in the absence of public institutions, such as schools, parks, and libraries, and in the absence of a collective political identity among Atlantic Station patrons. The disappearance of the state in the material spaces of the city suggests that the neoliberal project of individualism and consumerism is transforming the very notion of livability and the democratic possibilities of what makes urban space "livable".

 

‘It's a public, I reckon': Publicness and a Suburban Shopping Mall in Sydney's Southwest

A. Tyndall

10.1111/j.1745-5871.2009.00621.x

 

Traditionally, public space has been perceived as an integral part of fully functioning liberal democracy. Yet much research argues that public space is in decline due to regimes of neoliberal governance paralleled with a growth in quasi-public spaces such as shopping malls, casinos and gated communities. It is argued that these new spatial forms posit a commercialised, sanitised and ultimately exclusionary urban form in place of more egalitarian, engaging and ultimately democratic public spaces. Increasingly, however, urban research has questioned the veracity of the claims made about the nature of traditional public space as well as investigating the marginal and contingent nature of publicness as constituted by and enacted in a variety of places. Drawing on Foucault's concept of heterotopic space, this paper reports on a qualitative study based on focus group interviews conducted with users of a suburban shopping mall in Sydney's southwest. The research uncovers both a more complex and less overtly deterministic publicness than has previously been identified in such spaces. From these findings the paper argues for a conception of publicity which moves beyond the zero-sum game approach endemic in much work in this area to one which analyses the qualitative effect quasi-public spaces are having on the nature of publicness in the Australian context. The paper concludes by arguing that a rethinking of publicness allows room for the emergence of a more progressive public ethic.

 

Secular iconoclasm: purifying, privatizing, and profaning public faith

N. Howe

10.1080/14649360903068092

 

Secularists tend not to destroy religious icons, but to displace them. This, too, is a form of iconoclasm. By excluding certain symbols from public places, they treat them as idols—threats to the freedom of rational, rights-bearing citizens and thus to the sacred spaces of the democratic nation-state. In so doing, they inscribe these supposedly neutral spaces with specific cultural and religious norms. Yet contrary to increasingly popular arguments on both the right and left, these norms vary greatly from place to place, audience to audience, actor to actor. This variety makes it difficult if not impossible to speak of a coherent secular spatiality, let alone a coherent secular subject. In the USA, iconoclastic performances produce secular places in great variety, some hostile to religion, others to religious nationalism, and others to the state. Focusing on legal conflicts over state-sponsored religious speech, this article aims to problematize the notion of ‘secular normativity' by analyzing some of this geographical diversity.

 

Locating the public in research and practice

L.A. Staeheli, D. Mitchell

10.1177/0309132507083509

 

Discussions of public space and the public have become complicated in recent years. This article seeks to bring some clarity to these discussions by examining where participants in public space debates `locate' the public — those spheres or realms where participants believe a public is constituted and where public interest is found. To identify the ways in which public space is conceptualized and located, we analyze the literature on public space, interviews with scholars actively involved in public space research, and interviews with participants in a series of public space controversies in the USA. We find that differing definitions of `the public' that underlie these conceptualizations are rooted in strongly held political orientations and normative visions of democracy. But we also find that there is considerable overlap in how participants frame their understandings of publicity, and thus there is a basis for more thorough debate and even transformation of policy and practice.

 

Thou Shalt Not Misinterpret: Landscape as Legal Performance

N. Howe

10.1080/00045600701879466

 

Since the early 1990s cities and towns across the United States have been embroiled in a series of increasingly contentious lawsuits over displays of the Ten Commandments on government land. Part of a broader wave of litigation over religious iconography in public places, these cases are seen to embody a national confrontation between conservative Christians and their liberal enemies over the separation of church and state. In many cases, one side argues that the displays merely acknowledge the nation's Judeo-Christian heritage, the other that they alienate non-Christians and thus exclude them from public life. On both sides, efforts to explain how landscapes "speak"—and more important, to describe the psychological effects of such speech—have focused on the affective modalities of observation. How, courts ask, should a reasonable observer respond emotionally to religious symbols in the public square? What, if anything, is the political significance of his or her feelings? This debate is best understood as a form of agonistic social performance that serves not only to define substantive legal rights but also to shape the moral and aesthetic sensibilities of its audiences. By dramatizing landscape's power to inspire and overawe, alienate and offend, its adversaries seek to affirm different standards of public discourse and civic piety. In so doing, they ground the poetics of public space in the politics of national memory.

 

Locating Impropriety: Street Drinking, Moral Order, and the Ideological Dilemma of Public Space

J. Dixon, M. Levine, R. McAuley

10.1111/j.1467-9221.2006.00002.x

 

Drawing on research in urban sociology, cultural geography, and social psychology, this paper explores some of the moral rules that govern social relations in public places. In particular, we consider how certain practices become classified as everyday incivilities—infractions of the moral order that sustains public life. In order to develop this notion, we draw illustrations from an ongoing research project that is investigating social attitudes towards "street drinking," an activity that has led to the creation of "alcohol-free zones" in over 100 British cities during the past decade. As an emergent theme, this research has suggested that the classification of street drinking as either acceptable or unacceptable conduct is contingent upon the social construction of public space that users invoke. This theme is discussed in the context of wider struggles over citizenship and social control in the public domain—struggles manifest within "ideological dilemmas" (Billig et al., 1988) over the limits of free conduct, the tension between open and closed public spaces, and the attempt to distinguish "admissible" from "inadmissible" publics.

 

What is holistic landscape ecology? A conceptual introduction

Z. Naveh

10.1016/S0169-2046(00)00077-3

 

To meet the challenges of the emerging information-rich society, landscape ecology must become a holistic problem-solving oriented science by joining the transdisciplinary scientific revolution with a paradigm shift from conventional reductionistic and mechanistic approaches to holistic and organismic approaches of wholeness, connectedness and ordered complexity. Its central holistic concept is the Total Human Ecosystem as the highest level of co-evolutionary complexity in the global ecological hierarchy, with solar energy powered biosphere and fossil energy powered technosphere landscapes as its concrete systems. Landscape ecology could contribute to their structural and functional integration into a coherent sustainable ecosphere and thereby to the establishment of a sustainable balance between attractive and productive biosphere landscapes and healthy and livable technosphere landscapes for this and future generation. By utilizing new insights in self-organization of autopioetic systems and their cross-catalytic networks in the Total Human Ecosystem for synergistic benefits of the people, their economy and landscapes, such holistic landscape ecology together with other mission-driven transdisciplinary environmental sciences could serve as a catalyst for the urgently needed post-industrial symbiosis between nature and human society. This would ensure also their further biological and cultural evolution.

 

Creating landscape patterns by forest cutting: Ecological consequences and Principles

J.F. Franklin, R.T.T. Forman

10.1007/BF02275261

 

Landscape structural characteristics, such as patch size, edge length, and configuration, are altered markedly when management regimes are imposed on primeval landscapes. The ecological consequences of clearcutting patterns were explored by using a model of the dispersed patch or checkerboard system currently practiced on federal forest lands in the western United States. Thresholds in landscape structure were observed on a gradient of percentages of landscape cutover. Probability of disturbance,e.g., wildfire and windthrow, and biotic components,e.g., species diversity and game populations, are highly sensitive to these structural changes. Altering the spatial configuration and size of clearcuts provides an opportunity to create alternative landscapes that differ significantly in their ecological characteristics. Both ecosystem and heterogeneous landscape perspectives are critical in resource management.

 

Characterizing the complexity of landscape boundaries by remote sensing

J.P. Metzger,  E. Muller

10.1007/BF02093740

 

This paper presents a method for characterizing the complexity of landscape boundaries by remote sensing. This characterization is supported by a new boundary typology, that takes into account points where three or more landcovers converge (i.e., convergency points or coverts). Landscape boundary richness and diversity indices were proposed and calculated over 19 landscapes in South-East Brazil. Results showed that landscape boundaries, especially convergency points, provided an enrichment in landscape pattern analysis. Landcover boundary diversities were significantly related to landcover shape: elongated riparian units had the highest values for boundary diversity and coverts proportion indices. On the other hand, landscape analysis showed that indices of shape, richness, diversity and coverts proportion provided an additional evaluation of landcover spatial distribution within the landscape.

 

Relationships between landforms, geomorphic processes, and plant communities on a watershed in the northern Chihuahuan Desert

S. M. Wondzell, G. L. Cunningham, D. Bachelet

10.1007/BF02447522

 

The close correlation of plant communities to landforms and geomorphic surfaces resulted from differences in the redistribution of water and organic matter between landform in the northern Chihuahuan Desert. Biotic processes are limited by water and nitrogen, and the interactions between landforms, geomorphic processes, soils, and plant communities control the redistribution of these limiting resources within internally drained catchments. Geomorphic processes are regulated by the geologic structure and gross topographic relief of internally drained catchments over geological time scales. Land forming processes can be viewed as static at time scales of 10's to 100's of years, with individual landforms regulating geomorphic processes, namely erosion and deposition resulting from the horizontal redistribution of water within the catchment. The vegetation composition is a critical feedback, reinforcing the erosional or depositional geomorphic processes that dominate each landform.

The Jornada Long-Term Ecological Research site may be one of the simplest cases in which to decipher the relationship between landforms, geomorphic processes and plant communities. However, these geomorphic processes are common to all internally drained catchments throughout the Basin and Range Province, and result in the development of characteristic landforms and associated vegetation communities. Although the patterns may be modified by differences in parent material, watershed size, and land use history — erosional, depositional, and transportational landforms can still be identified.

The sharpness of ecotones between plant communities on individual landforms is related to the degree to which landforms are linked through the flow of water and sediment. Sharp ecotones occurred at the transition from depositional to erosional landforms where little material was transferred and steep environmental gradients are maintained. Gradual ecotones occurred at the transition from erosional to depositional landforms where large quantities of material were transferred leading to the development of a gradual environmental gradient.

The relationships between geomorphic processes and vegetation communities that we describe have important implications for understanding the desertification of grasslands throughout semi-arid regions of North America. Disturbances such as grazing and climate change alter the composition of plant communities, thereby affecting the feedbacks to geomorphic processes, eventually changing drainage patterns and the spatial patterns of plant communities supported within the landscape.

 

Geomorphology and ecology: Unifying themes for complex systems in biogeomorphology

J. A. Stallins

10.1016/j.geomorph.2006.01.005

 

The interaction of geomorphic and ecologic landscape components has been largely conceptualized as independent. In one direction, geomorphic processes and landforms shape the distribution of biota. Conversely, in the other direction, biota modify geomorphic processes and landforms. Increasingly, the interactions between geomorphic and ecological components are more circular and developmentally intertwined. In this paper, I integrate these two independent perspectives within the framework of complexity theory. I outline four themes that characterize complex systems in biogeomorphology: multiple causality and the concept of recursivity, the influence of organisms that function as ecosystem engineers, the expression of an ecological topology, and ecological memory. Implicit in all of these themes is the recognition that biogeomorphic systems are open and path dependent. They may exhibit a range of assembly states, from self-reinforcing stability domains to more transient configurations of organisms and environment.

 

Strategies for European innovation policy in the transport field

H. J. van Zuylen, K. M. Weber

10.1016/S0040-1625(02)00191-9

 

Technology offers opportunities to realise policy goals. The FANTASIE project, executed for the European Commission, has done a search for promising technological innovations in transport and has assessed their possible impacts on the goals of the Common Transport Policy. Individual policy measures that could foster these promising technological innovations have been identified. Beyond individual measures, robust and adaptive strategies need to be developed that can be adjusted to changing circumstances in order to cope with the complexity and high level of uncertainty involved. In addition, the balance between national and European policy measures deserves particular  attention. This leads us to suggest a number of policy packages that reflect the aforementioned principles of transport innovation policy design, as well as the specific constraints of the European policy context.

 

Infrastructure, programs, and policies to increase bicycling: An international review

J.Pucher, J.Dill, S. Handy

10.1016/j.ypmed.2009.07.028

 

Objectives. To assess existing research on the effects of various interventions on levels of bicycling. Interventions include infrastructure (e.g., bike lanes and parking), integration with public transport, education and marketing programs, bicycle access programs, and legal issues.

Methods. A comprehensive search of peer-reviewed and non-reviewed research identified 139 studies. Study methodologies varied considerably in type and quality, with few meeting rigorous standards. Secondary data were gathered for 14 case study cities that adopted multiple interventions.

Results. Many studies show positive associations between specific interventions and levels of bicycling. The 14 case studies show that almost all cities adopting comprehensive packages of interventions experienced large increases in the number of bicycle trips and share of people bicycling.

Conclusions. Most of the evidence examined in this review supports the crucial role of public policy in encouraging bicycling. Substantial increases in bicycling require an integrated package of many different, complementary interventions, including infrastructure provision and pro-bicycle programs, supportive land use planning, and restrictions on car use.

 

Applying the new appraisal approach to transport policy at the local level in the UK

W.Walton, J. Shaw

10.1016/S0966-6923(02)00051-0

 

In 1998 the UK government introduced a new, integrated transport policy signalling a move away from the principles of ‘predict and provide' towards those of ‘new realism'. As part of this policy shift, transport strategies are now to be assessed under the New Approach to Appraisal (NATA) which is designed to promote sustainability and provide a sterner test for new road proposals. Despite this, it is already evident that the construction of new roads has remained a cornerstone of the government's new transport strategy––albeit alongside considerable investment in public transport––which has been described as pragmatic multimodalism. This paper examines how the new appraisal approach has been applied at the local level in the formulation of the first Local Transport Strategy (LTS) for Aberdeen in north east Scotland and questions the effectiveness of NATA (and its Scottish equivalent, the New Appraisal Methodology, or NAM), as currently formulated, at promoting the delivery of genuinely integrated and sustainable local transport strategies. The analysis of Aberdeen's LTS is used to inform a discussion about the possible implications for future local transport policies across the UK.

 

Socio-political analysis of French transport policies: The state of the practices

V. Kaufmann, Ch. Jemelin, G. Pflieger, L.Pattaroni

10.1016/j.tranpol.2007.10.001

 

The article takes stock of transport policy research which was carried out in France between 1995 and 2002 or which deals specifically with French transport policy.

The article is divided into three parts. The first deals with a quantitative analysis of the body of research, which enables us to pinpoint those studies which deal specifically with our chosen topic. The second part consists of an analysis of the content of the selected research according to the sequential model used to analyse public policy, i.e. starting with the construction of the problem and ending with an evaluation of the measures introduced to solve the problem. The third and final part provides a critical summary of the main research findings.

 

The Oslo and Bergen toll rings and road-building investment – Effect on traffic development

and congestion

J. I.Lian

10.1016/j.jtrangeo.2007.08.004

 

When the toll rings around Bergen and Oslo were established in 1986 and 1990, respectively, they were part of major schemes to speed up road investments. In Oslo, 20% of the revenue was allocated for investments in public transport, while in Bergen, third the size of Oslo, investments were exclusively for road transport. This article focuses on how city size and public transport policy may influence effects of infrastructure investments on car traffic development and congestion. Oslo, having one million inhabitants, experienced moderate growth in car traffic, and public transport traffic volumes experienced a stronger growth than the national average. Still, congestion levels were only slightly changed. The smaller city Bergen, however, experienced a strong increase in car traffic and a strong decrease in public transport traffic. Despite the strong growth in car traffic, increased road capacity still seems to have resolved congestion problems, at least during the period under study. The result seems to indicate that in smaller cities increased road capacity might relieve congestion even if road traffic increases. Urban sprawl seems to be a major factor behind increased car traffic in both cities.

 

Transport policy in Australia - Evolution, learning and policy transfer

D.J.Bray, M. A.P.Taylor , D. Scrafton

10.1016/j.tranpol.2010.10.005

 

Urban transport policy in Australia has changed markedly over the period since the first generation of modern urban transport strategies were published in the 1960s. This is illustrated through a review of 43 transport strategies published for the five largest cities (Sydney, Melbourne, Brisbane, Perth and Adelaide) in Australia between 1965 and 2010. The review is complemented with observations from a survey of public servants in the policy and strategy divisions of state and territory transport agencies. The results of this research are examined using the Dolowitz–Marsh framework, considering the need to seek policy transfer, who is involved, what is transferred, from where policy lessons are learnt, the degree of transfer, constraints to policy learning and demonstration that transfer has occurred. The evidence for policy transfer and learning is mixed. Transport policy adopted by the states of Australia for their respective capital cities has been remarkably similar between the cities and has changed in a similar way over time, indicating the almost seamless transfer of concepts. Less positively, there is little published evidence that the performance of previous strategies has been critically examined and lessons learned, and that the approaches adopted in strategies are superior to alternative approaches and are able to achieve the objectives set for them.