bluuebunny/crossref_metadata_2025 huggingface dataset:
Mismatch between observed and modeled trends in dissolved upper-ocean oxygen over the last 50 yr
Authors: Stramma L. , Oschlies A. , Schmidtko S.
Published: October 2012

Abstract. Observations and model runs indicate trends in dissolved oxygen (DO) associated with current and ongoing global warming. However, a large-scale observation-to-model comparison has been missing and is presented here. This study presents a first global compilation of DO measurements covering the last 50 yr. It shows declining upper-ocean DO levels in many regions, especially the tropical oceans, whereas areas with increasing trends are found in the subtropics and in some subpolar regions. For the Atlantic Ocean south of 20° N, the DO history could even be extended back to about 70 yr, showing decreasing DO in the subtropical South Atlantic. The global mean DO trend between 50° S and 50° N at 300 dbar for the period 1960 to 2010 is –0.066 μmol kg−1 yr−1. Results of a numerical biogeochemical Earth system model reveal that the magnitude of the observed change is consistent with CO2-induced climate change. However, the pattern correlation between simulated and observed patterns of past DO change is negative, indicating that the model does not correctly reproduce the processes responsible for observed regional oxygen changes in the past 50 yr. A negative pattern correlation is also obtained for model configurations with particularly low and particularly high diapycnal mixing, for a configuration that assumes a CO2-induced enhancement of the C : N ratios of exported organic matter and irrespective of whether climatological or realistic winds from reanalysis products are used to force the model. Depending on the model configuration the 300 dbar DO trend between 50° S and 50° N is −0.027 to –0.047 μmol kg−1 yr−1 for climatological wind forcing, with a much larger range of –0.083 to +0.027 μmol kg−1 yr−1 for different initializations of sensitivity runs with reanalysis wind forcing. Although numerical models reproduce the overall sign and, to some extent, magnitude of observed ocean deoxygenation, this degree of realism does not necessarily apply to simulated regional patterns and the representation of processes involved in their generation. Further analysis of the processes that can explain the discrepancies between observed and modeled DO trends is required to better understand the climate sensitivity of oceanic oxygen fields and predict potential DO changes in the future.
Northern peatland carbon stocks and dynamics: a review
Authors: Yu Z. C.
Published: October 2012

Abstract. Peatlands contain a large belowground carbon (C) stock in the biosphere, and their dynamics have important implications for the global carbon cycle. However, there are still large uncertainties in C stock estimates and poor understanding of C dynamics across timescales. Here I review different approaches and associated uncertainties of C stock estimates in the literature, and on the basis of the literature review my best estimate of C stocks and uncertainty is 500 ± 100 (approximate range) gigatons of C (Gt C) in northern peatlands. The greatest source of uncertainty for all the approaches is the lack or insufficient representation of data, including depth, bulk density and carbon accumulation data, especially from the world's large peatlands. Several ways to improve estimates of peat carbon stocks are also discussed in this paper, including the estimates of C stocks by regions and further utilizations of widely available basal peat ages. Changes in peatland carbon stocks over time, estimated using Sphagnum (peat moss) spore data and down-core peat accumulation records, show different patterns during the Holocene, and I argue that spore-based approach underestimates the abundance of peatlands in their early histories. Considering long-term peat decomposition using peat accumulation data allows estimates of net carbon sequestration rates by peatlands, or net (ecosystem) carbon balance (NECB), which indicates more than half of peat carbon (> 270 Gt C) was sequestrated before 7000 yr ago during the Holocene. Contemporary carbon flux studies at 5 peatland sites show much larger NECB during the last decade (32 ± 7.8 (S.E.) g C m−2 yr–1) than during the last 7000 yr (∼ 11 g C m−2 yr–1), as modeled from peat records across northern peatlands. This discrepancy highlights the urgent need for carbon accumulation data and process understanding, especially at decadal and centennial timescales, that would bridge current knowledge gaps and facilitate comparisons of NECB across all timescales.
Tidal and seasonal carbon and nutrients dynamics of the Guadalquivir Estuary and the Bay of Cádiz (SW Iberian Peninsula)
Authors: Ribas-Ribas M. , Carracedo L. I. , Anfuso E. , Forja J. M.
Published: October 2012

Abstract. To study the effects of the physical environment on carbon and nutrients cycles dynamics in the north eastern shelf of the Gulf of Cádiz, changes in currents, tides, salinity, temperature, carbon system parameters (fugacity of CO2 (fCO2), dissolved organic carbon, dissolved inorganic carbon and pH) and others related (dissolved oxygen, total dissolved nitrogen, nutrients and suspended particulate matter) were measured in transects across the Guadalquivir Estuary and Bay of Cádiz mouths. Thus, the main objective of this study is to investigate the influence of these inner ecosystems on the carbon and nutrient distributions in the adjacent continental shelf. Three cruises have been undertaken in June 2006, November 2006 and February 2007, each one covering one complete tidal cycle during June, both systems were exporting components to the adjacent continental shelf of the Gulf of Cádiz. In an annual scale, Guadalquivir Estuary exported components while Bay of Cádiz imported them. Diurnal variability of fCO2 could have a potentially important implication on the estimate of air-sea CO2 fluxes. Monthly studies should be undertaken to completely understand this dynamic system.
The Nexus Land-Use model version 1.0, an approach articulating biophysical potentials and economic dynamics to model competition for land-use
Authors: Souty F. , Brunelle T. , Dumas P. , Dorin B. , Ciais P. , Crassous R. , Müller C. , Bondeau A.
Published: October 2012

Abstract. Interactions between food demand, biomass energy and forest preservation are driving both food prices and land-use changes, regionally and globally. This study presents a new model called Nexus Land-Use version 1.0 which describes these interactions through a generic representation of agricultural intensification mechanisms within agricultural lands. The Nexus Land-Use model equations combine biophysics and economics into a single coherent framework to calculate crop yields, food prices, and resulting pasture and cropland areas within 12 regions inter-connected with each other by international trade. The representation of cropland and livestock production systems in each region relies on three components: (i) a biomass production function derived from the crop yield response function to inputs such as industrial fertilisers; (ii) a detailed representation of the livestock production system subdivided into an intensive and an extensive component, and (iii) a spatially explicit distribution of potential (maximal) crop yields prescribed from the Lund-Postdam-Jena global vegetation model for managed Land (LPJmL). The economic principles governing decisions about land-use and intensification are adapted from the Ricardian rent theory, assuming cost minimisation for farmers. In contrast to the other land-use models linking economy and biophysics, crops are aggregated as a representative product in calories and intensification for the representative crop is a non-linear function of chemical inputs. The model equations and parameter values are first described in details. Then, idealised scenarios exploring the impact of forest preservation policies or rising energy price on agricultural intensification are described, and their impacts on pasture and cropland areas are investigated.
Technical Note: Improving computational efficiency in large linear inverse problems: an example from carbon dioxide flux estimation
Authors: Yadav V. , Michalak A. M.
Published: October 2012

Abstract. Addressing a variety of questions within Earth science disciplines entails the inference of the spatio-temporal distribution of parameters of interest based on observations of related quantities. Such estimation problems often represent inverse problems that are formulated as linear optimization problems. Computational limitations arise when the number of observations and/or the size of the discretized state space become large, especially if the inverse problem is formulated in a probabilistic framework and therefore aims to assess the uncertainty associated with the estimates. This work proposes two approaches to lower the computational costs and memory requirements for large linear space-time inverse problems, taking the Bayesian approach for estimating carbon dioxide (CO2) emissions and uptake (a.k.a. fluxes) as a prototypical example. The first algorithm can be used to efficiently multiply two matrices, as long as one can be expressed as a Kronecker product of two smaller matrices, a condition that is typical when multiplying a sensitivity matrix by a covariance matrix in the solution of inverse problems. The second algorithm can be used to compute a posteriori uncertainties directly at aggregated spatio-temporal scales, which are the scales of most interest in many inverse problems. Both algorithms have significantly lower memory requirements and computational complexity relative to direct computation of the same quantities (O(n2.5) vs. O(n3)). For an examined benchmark problem, the two algorithms yielded a three and six order of magnitude increase in computational efficiency, respectively, relative to direct computation of the same quantities. Sample computer code is provided for assessing the computational and memory efficiency of the proposed algorithms for matrices of different dimensions.
3D GEOVISUALIZATION – DEFINITION AND STRUCTURES FOR THE ASSESSMENT OF USEFULNESS
Authors: Bleisch S.
Published: October 2012

Abstract. 3D geovisualizations are quite popular, typical examples include 3D city models or virtual globes. They are reported to be more useful when they not only depict the real world but also include additional information. The creation of 3D geovisualizations is often very technology driven and we are yet missing solid theory. The paper aims to compile definitions and structures that allow the consideration and evaluation of the usefulness of 3D geovisualization with additional abstract information less focussing on technical and implementational aspects. The different purposes of 3D geovisualizations, as illustrated through the geovisualization cube, together with considerations of the specific characteristics of 3D visualizations, for example the inherent need for navigation, build the base for conscious design decisions. Those decisions can build upon existing theories from related disciplines, such as cartography or information visualization, but need to consider onto what dimension of the three-dimensional space the data is mapped. A categorisation of the use of 3D space is discussed before reviewing different task definitions. A generic task structure which allows separation between interaction and navigational tasks together with the presented definitions and the categorisation of using 3D space build the basic framework for considering, evaluating and discussing the usefulness of 3D geovisualizations and ultimately support 3D geovisualization theory building. The knowledge of what works well and is useful in specific contexts can improve future technological developments and hopefully make 3D geovisualizations become an important tool for the visual exploration of 3D geospatial data sets.
LANDSCAPE VISUALISATION ON THE INTERNET
Authors: Imhof M. P. , Cox M. T. , Harvey D. W. , Heemskerk G. E. , Pettit C. J.
Published: October 2012

Abstract. The Victorian Resources Online (VRO) website (http://www.dpi.vic.gov.au/vro) is the principal means for accessing landscapebased information in Victoria. In this paper we introduce a range of online landscape visualisations that have been developed to enhance existing static web content around the nature and distribution of Victoria's landforms and soils as well as associated processes. Flash is used to develop online visualisations that include interactive landscape panoramas, animations of soil and landscape processes and videos of experts explaining features in the field as well as landscape "flyovers". The use of interactive visualisations adds rich information multimedia content to otherwise static pages and offers the potential to improve user's appreciation and understanding of soil and landscapes. Visualisation is becoming a key component of knowledge management activities associated with VRO – proving useful for both "knowledge capture" (from subject matter specialists) and "knowledge transfer" to a diverse user base. A range of useful visualisation products have been made available online, with varying degrees of interactivity and suited to a variety of users. The use of video files, animation and interactive visualisations is adding rich information content to otherwise static web pages. These information products offer new possibilities to enhance learning of landscapes and the effectiveness of these will be tested as the next phase of development.
SIMULTANEOUS VISUALIZATION OF DIFFERENT UTILITY NETWORKS FOR DISASTER MANAGEMENT
Authors: Semm S. , Becker T. , Kolbe T. H.
Published: October 2012

Abstract. Cartographic visualizations of crises are used to create a Common Operational Picture (COP) and enforce Situational Awareness by presenting and representing relevant information. As nearly all crises affect geospatial entities, geo-data representations have to support location-specific decision-making throughout the crises. Since, Operator's attention span and their working memory are limiting factors for the process of getting and interpreting information; the cartographic presentation has to support individuals in coordinating their activities and with handling highly dynamic situations. The Situational Awareness of operators in conjunction with a COP are key aspects of the decision making process and essential for coming to appropriate decisions. Utility networks are one of the most complex and most needed systems within a city. The visualization of utility infrastructure in crisis situations is addressed in this paper. The paper will provide a conceptual approach on how to simplify, aggregate, and visualize multiple utility networks and their components to meet the requirements of the decision-making process and to support Situational Awareness.
EVALUATING PHOTOGRAMMETRIC APPROACH OF IMAGE-BASED POSITIONING
Authors: Li X. , Wang J.
Published: October 2012

Abstract. In recent years, researches in the domain of location-based services have increasingly focused on developing and utilizing alternative positioning techniques for in GPS-denied environment. Image based positioning technique holds good promise for such applications. In this paper, a previously proposed image-based positioning system using photogrammetric methods has been put into rigorous evaluation. The precision and accuracy of such photogrammetric approach of image-based positioning is depending on the precision and accuracy of final space resection process, which is a function of PGCP distribution and measurement accuracy, and any factor that has certain impact on either of these two major components will to certain degree influence final positioning accuracy. Therefore in this article, the way that different factors influencing the positioning accuracy are analysed through both mathematical model and experiments, which includes simulations and tests based on real data. Through evaluation of such system, we aims at better understanding image-based positioning system alike so as to find its strength, weaknesses and ways to improve the overall performance for it to realize its full potential.
A New Models for Emergency Evacuation under the Disaster Condition
Authors: Tang L. , Yang X. , Huang F. , Xu H. , Li Q.
Published: October 2012

Abstract. People must face many disasters every day, which cause losses in property and human lives. It is significant how to establish the emergency evacuation model and for high density population in large areas according to the actual situation of their emergency evacuation. This paper put forward a Multi-levels Emergency Evacuation Model (MEE) based on the collective evacuation for high density of population in large areas under the earthquake condition in China, which firstly find the best ways from the multi-gathering points(Origins) in the disaster area to multi-settling points(Destinations )in the safe area based on the road impedance such as the traffic, road speed limit and pavement damage to weight the evacuation ability of road network, and secondly determine the evacuation auto numbers on the every routes which is at the target to deliver all the evacuating people from the Origins to Destinations in the shortest time. The experiment area is Dezhou city in Shandong province of China, and an emergency evacuation platform was put up according to the multilevel emergency evacuation model using Google map API and C# as development platform, and the result show us that MEE is promised to be a new methods for emergency evacuation.
ONTOLOGICAL STANDARDIZATION FOR HISTORICAL MAP COLLECTIONS: STUDYING THE GREEK BORDERLINES OF 1881
Authors: Gkadolou E. , Tomai E. , Stefanakis E. , Kritikos G.
Published: October 2012

Abstract. Historical maps deliver valuable historical information which is applicable in several domains while they document the spatiotemporal evolution of the geographical entities that are depicted therein. In order to use the historical cartographic information effectively, the maps' semantic documentation becomes a necessity for restoring any semantic ambiguities and structuring the relationship between historical and current geographical space. This paper examines cartographic ontologies as a proposed methodology and presents the first outcomes of the methodology applied for the historical map series «Carte de la nouvelle frontière Turco-Grecque» that sets the borderlines between Greece and Ottoman Empire in 1881. The map entities were modelled and compared to the current ones so as to record the changes in their spatial and thematic attributes and an ontology was developed in Protégé OWL Editor 3.4.4 for the attributes that thoroughly define a historical map and the digitised spatial entities. Special focus was given on the Greek borderline and the changes that it caused to other geographic entities.
THE DEVELOPMENT OF CADASTRAL DOMAIN MODEL ORIENTED AT UNIFIED REAL ESTATE REGISTRATION OF CHINA BASED ON ONTOLOGY
Authors: Li M. , Zhu X. , Shen C. , Chen D. , Guo W.
Published: October 2012

Abstract. With the certain regulation of unified real estate registration taken by the Property Law and the step-by-step advance of simultaneous development in urban and rural in China, it is the premise and foundation to clearly specify property rights and their relations in promoting the integrated management of urban and rural land. This paper aims at developing a cadastral domain model oriented at unified real estate registration of China from the perspective of legal and spatial, which set up the foundation for unified real estate registration, and facilitates the effective interchange of cadastral information and the administration of land use. The legal cadastral model is provided based on the analysis of gap between current model and the demand of unified real estate registration, which implies the restrictions between different rights. Then the new cadastral domain model is constructed based on the legal cadastral domain model and CCDM (van Oosterom et al., 2006), which integrate real estate rights of urban land and rural land. Finally, the model is validated by a prototype system. The results show that the model is applicable for unified real estate registration in China.
REAL TIME SEMANTIC INTEROPERABILITY IN AD HOC NETWORKS OF GEOSPATIAL DATA SOURCES: CHALLENGES, ACHIEVEMENTS AND PERSPECTIVES
Authors: Mostafavi M. A. , Bakillah M.
Published: October 2012

Abstract. Recent advances in geospatial technologies have made available large amount of geospatial data. Meanwhile, new developments in Internet and communication technologies created a shift from isolated geospatial databases to ad hoc networks of geospatial data sources, where data sources can join or leave the network, and form groups to share data and services. However, effective integration and sharing of geospatial data among these data sources and their users are hampered by semantic heterogeneities. These heterogeneities affect the spatial, temporal and thematic aspects of geospatial concepts. There have been many efforts to address semantic interoperability issues in the geospatial domain. These efforts were mainly focused on resolving heterogeneities caused by different and implicit representations of the concepts. However, many approaches have focused on the thematic aspects, leaving aside the explicit representation of spatial and temporal aspects. Also, most semantic interoperability approaches for networks have focused on automating the semantic mapping process. However, the ad hoc network structure is continuously modified by source addition or removal, formation of groups, etc. This dynamic aspect is often neglected in those approaches. This paper proposes a conceptual framework for real time semantic interoperability in ad hoc networks of geospatial data sources. The conceptual framework presents the fundamental elements of real time semantic interoperability through a hierarchy of interrelated semantic states and processes. Then, we use the conceptual framework to set the discussion on the achievements that have already been made, the challenges that remain to be addressed and perspectives with respect to these challenges.
FACILITATING INTEGRATED SPATIO-TEMPORAL VISUALIZATION AND ANALYSIS OF HETEROGENEOUS ARCHAEOLOGICAL AND PALAEOENVIRONMENTAL RESEARCH DATA
Authors: C. Willmes  , S. Brocks  , D. Hoffmeister  , C. Hütt  , D. Kürner  , K. Volland  , G. Bareth
Published: October 2012

Abstract. In the context of the Collaborative Research Centre 806 "Our way to Europe" (CRC806), a research database is developed for integrating data from the disciplines of archaeology, the geosciences and the cultural sciences to facilitate integrated access to heterogeneous data sources. A practice-oriented data integration concept and its implementation is presented in this contribution. The data integration approach is based on the application of Semantic Web Technology and is applied to the domains of archaeological and palaeoenvironmental data. The aim is to provide integrated spatio-temporal access to an existing wealth of data to facilitate research on the integrated data basis. For the web portal of the CRC806 research database (CRC806-Database), a number of interfaces and applications have been evaluated, developed and implemented for exposing the data to interactive analysis and visualizations.
OPTIMIZATION OF LAND USE SUITABILITY FOR AGRICULTURE USING INTEGRATED GEOSPATIAL MODEL AND GENETIC ALGORITHMS
Authors: Mansor S. B. , Pormanafi S. , Mahmud A. R. B. , Pirasteh S.
Published: October 2012

Abstract. In this study, a geospatial model for land use allocation was developed from the view of simulating the biological autonomous adaptability to environment and the infrastructural preference. The model was developed based on multi-agent genetic algorithm. The model was customized to accommodate the constraint set for the study area, namely the resource saving and environmental-friendly. The model was then applied to solve the practical multi-objective spatial optimization allocation problems of land use in the core region of Menderjan Basin in Iran. The first task was to study the dominant crops and economic suitability evaluation of land. Second task was to determine the fitness function for the genetic algorithms. The third objective was to optimize the land use map using economical benefits. The results has indicated that the proposed model has much better performance for solving complex multi-objective spatial optimization allocation problems and it is a promising method for generating land use alternatives for further consideration in spatial decision-making.
EARTH OBSERVATION DATA INTEROPERABILITY ARRANGEMENT WITH ONTOLOGY REGISTRY
Authors: Nagai M. , Ono M. , Shibasaki R.
Published: October 2012

Abstract. Standardization organizations are working for syntactic and schematic level of interoperability. At the same time, semantic interoperability must be considered as a heterogeneous condition and also very diversified with a large-volume data. The ontology registry has been developed and ontological information such as technical vocabularies for earth observation has been collected for data interoperability arrangement. This is a very challenging method for earth observation data interoperability because collaboration or cooperation with scientists of different disciplines is essential for common understanding. Multiple semantic MediaWikis are applied to register and update technical vocabularies as a part of the ontology registry, which promises to be a useful tool for users. In order to invite contributions from the user community, it is necessary to provide sophisticated and easy-to-use tools and systems, such as table-like editor, reverse dictionary, and graph representation for sustainable development and usage of ontological information. Registered ontologies supply the reference information required for earth observation data retrieval. We proposed data/metadata search with ontology such as technical vocabularies and visualization of relations among dataset to very large scale and various earth observation data.
A VOMR-TREE BASED PARALLEL RANGE QUERY METHOD ON DISTRIBUTED SPATIAL DATABASE
Authors: Fu Z. , Liu S.
Published: October 2012

Abstract. Spatial index impacts upon the efficiency of spatial query seriously in distributed spatial database. In this paper, we introduce a parallel spatial range query algorithm, based on VoMR-tree index, which incorporates Voronoi diagrams into MR-tree, benefiting from the nearest neighbors. We first augments MR-tree to store the nearest neighbors and constructs the VoMR-tree index by Voronoi diagram. We then propose a novel range query algorithm based on VoMR-tree index. In processing a range query, we discuss the data partition method so that we can improve the efficiency by parallelization in distributed database. Just then a verification strategy is promoted. We show the superiority of the proposed method by extensive experiments using data sets of various sizes. The experimental results reveal that the proposed method improves the performance of range query processing up to three times in comparison with the widely-used R-tree variants.
BRAZILIAN AMAZONIA DEFORESTATION DETECTION USING SPATIO-TEMPORAL SCAN STATISTICS
Authors: C. A. O. Vieira  , N. T. Santos  , A. P. S. Carneiro  , A. A. S. Balieiro
Published: October 2012

Abstract. The spatio-temporal models, developed for analyses of diseases, can also be used for others fields of study, including concerns about forest and deforestation. The aim of this paper is to quantitatively check priority areas in order to combat deforestation on the Amazon forest, using the space-time scan statistic. The study area location is at the south of the Amazonas State and cover around 297.183 kilometre squares, including the municipality of Boca do Acre, Labrea, Canutama, Humaita, Manicore, Novo Aripuana e Apui County on the north region of Brazil. This area has showed a significant change for land cover, which has increased the number of deforestation's alerts. Therefore this situation becomes a concern and gets more investigation, trying to stop factors that increase the number of cases in the area. The methodology includes the location and year that deforestation’s alert occurred. These deforestation's alerts are mapped by the DETER (Detection System of Deforestation in Real Time in Amazonia), which is carry out by the Brazilian Space Agency (INPE). The software SatScanTM v7.0 was used in order to define space-time permutation scan statistic for detection of deforestation cases. The outcome of this experiment shows an efficient model to detect space-time clusters of deforestation’s alerts. The model was efficient to detect the location, the size, the order and characteristics about activities at the end of the experiments. Two clusters were considered actives and kept actives up to the end of the study. These clusters are located in Canutama and Lábrea County. This quantitative spatial modelling of deforestation warnings allowed: firstly, identifying actives clustering of deforestation, in which the environment government official are able to concentrate their actions; secondly, identifying historic clustering of deforestation, in which the environment government official are able to monitoring in order to avoid them to became actives again; and finally, verify that distances between the deforestation warning and the roads explain part of the significant clustering.
VISUAL AND STATISTICAL ANALYSIS OF DIGITAL ELEVATION MODELS GENERATED USING IDW INTERPOLATOR WITH VARYING POWERS
Authors: Asal F. F.
Published: October 2012

Abstract. Digital elevation data obtained from different Engineering Surveying techniques is utilized in generating Digital Elevation Model (DEM), which is employed in many Engineering and Environmental applications. This data is usually in discrete point format making it necessary to utilize an interpolation approach for the creation of DEM. Quality assessment of the DEM is a vital issue controlling its use in different applications; however this assessment relies heavily on statistical methods with neglecting the visual methods. The research applies visual analysis investigation on DEMs generated using IDW interpolator of varying powers in order to examine their potential in the assessment of the effects of the variation of the IDW power on the quality of the DEMs. Real elevation data has been collected from field using total station instrument in a corrugated terrain. DEMs have been generated from the data at a unified cell size using IDW interpolator with power values ranging from one to ten. Visual analysis has been undertaken using 2D and 3D views of the DEM; in addition, statistical analysis has been performed for assessment of the validity of the visual techniques in doing such analysis. Visual analysis has shown that smoothing of the DEM decreases with the increase in the power value till the power of four; however, increasing the power more than four does not leave noticeable changes on 2D and 3D views of the DEM. The statistical analysis has supported these results where the value of the Standard Deviation (SD) of the DEM has increased with increasing the power. More specifically, changing the power from one to two has produced 36% of the total increase (the increase in SD due to changing the power from one to ten) in SD and changing to the powers of three and four has given 60% and 75% respectively. This refers to decrease in DEM smoothing with the increase in the power of the IDW. The study also has shown that applying visual methods supported by statistical analysis has proven good potential in the DEM quality assessment.
EVALUATION OF ELEVATION, SLOPE AND STREAM NETWORK QUALITY OF SPOT DEMS
Authors: El Hage M. , Simonetto E. , Faour G. , Polidori L.
Published: October 2012

Abstract. Digital elevation models are considered the most useful data for dealing with geomorphology. The quality of these models is an important issue for users. This quality concerns position and shape. Vertical accuracy is the most assessed in many studies and shape quality is often neglected. However, both of them have an impact on the quality of the final results for a particular application. For instance, the elevation accuracy is required for orthorectification and the shape quality for geomorphology and hydrology. In this study, we deal with photogrammetric DEMs and show the importance of the quality assessment of both elevation and shape. For this purpose, we produce several SPOT HRV DEMs with the same dataset but with different template size, that is one of the production parameters from optical images. Then, we evaluate both elevation and shape quality. The shape quality is assessed with in situ measurements and analysis of slopes as an elementary shape and stream networks as a complex shape. We use the fractal dimension and sinuosity to evaluate the stream network shape. The results show that the elevation accuracy as well as the slope accuracy are affected by the template size. Indeed, an improvement of 1 m in the elevation accuracy and of 5 degrees in the slope accuracy has been obtained while changing this parameter. The elevation RMSE ranges from 7.6 to 8.6 m, which is smaller than the pixel size (10 m). For slope, the RMSE depends on the sampling distance. With a distance of 10 m, the minimum slope RMSE is 11.4 degrees. The stream networks extracted from these DEMs present a higher fractal dimension than the reference river. Moreover, the fractal dimension of the extracted networks has a negligible change according to the template size. Finally, the sinuosity of the stream networks is slightly affected by the change of the template size.
A MAXIMUM ENTROPY MODEL OF THE BEARDED CAPUCHIN MONKEY HABITAT INCORPORATING TOPOGRAPHY AND SPECTRAL UNMIXING ANALYSIS
Authors: Howard A. M. , Bernardes S. , Nibbelink N. , Biondi L. , Presotto A. , Fragaszy D. M. , Madden M.
Published: October 2012

Abstract. Movement patterns of bearded capuchin monkeys (Cebus (Sapajus) libidinosus) in northeastern Brazil are likely impacted by environmental features such as elevation, vegetation density, or vegetation type. Habitat preferences of these monkeys provide insights regarding the impact of environmental features on species ecology and the degree to which they incorporate these features in movement decisions. In order to evaluate environmental features influencing movement patterns and predict areas suitable for movement, we employed a maximum entropy modelling approach, using observation points along capuchin monkey daily routes as species presence points. We combined these presence points with spatial data on important environmental features from remotely sensed data on land cover and topography. A spectral mixing analysis procedure was used to generate fraction images that represent green vegetation, shade and soil of the study area. A Landsat Thematic Mapper scene of the area of study was geometrically and atmospherically corrected and used as input in a Minimum Noise Fraction (MNF) procedure and a linear spectral unmixing approach was used to generate the fraction images. These fraction images and elevation were the environmental layer inputs for our logistic MaxEnt model of capuchin movement. Our models' predictive power (test AUC) was 0.775. Areas of high elevation (>450 m) showed low probabilities of presence, and percent green vegetation was the greatest overall contributor to model AUC. This work has implications for predicting daily movement patterns of capuchins in our field site, as suitability values from our model may relate to habitat preference and facility of movement.
SPATIAL UNCERTAINTY IN LINE-SURFACE INTERSECTIONS WITH APPLICATIONS TO PHOTOGRAMMETRY
Authors: J. Marshall
Published: October 2012

Abstract. The fields of photogrammetry and computer vision routinely use line-surface intersections to determine the point where a line intersects with a surface. The object coordinates of the intersection point can be found using standard geometric and numeric algorithms, however expressing the spatial uncertainty at the intersection point may be challenging, especially when the surface morphology is complex. This paper describes an empirical method to characterize the unknown spatial uncertainty at the intersection point by propagating random errors in the stochastic model using repeated random sampling methods. These methods accommodate complex surface morphology and nonlinearities in the functional model, however the penalty is the resulting probability density function associated with the intersection point may be non-Gaussian in nature. A formal hypothesis test is presented to show that straightforward statistical inference tools are available whether the data is Gaussian or not. The hypothesis test determines whether the computed intersection point is consistent with an externally-derived known truth point. A numerical example demonstrates the approach in a photogrammetric setting with a single frame image and a gridded terrain elevation model. The results show that uncertainties produced by the proposed empirical method are intuitive and can be assessed with conventional methods found in textbook hypothesis testing.
KINETIC ALGORITHMS FOR HARBOUR MANAGEMENT
Authors: Gold C. M. , Goralski R. I.
Published: October 2012

Abstract. Modern harbour management for a busy port needs to resolve a variety of simultaneous problems. Harbour traffic may be busy and the waterways congested, both by the major shipping and by the attendant harbour tugs. The harbour channel may be narrow and tortuous, and rapidly changing tides may require frequent course adjustments. Navigation aids must be clearly specified and immediately identifiable, in order to permit safe passage for the vessels. This requires a GIS with attributes not easily available with traditional products. The GeoVS system is a kinetic GIS with full three-dimensional visualisation, so that ships, bathymetry and landscape may be viewed in a form that is immediately understandable to both harbour pilots and the harbour authority. The system is kinetic because the data structures used to preserve the topological relationships between ships, seafloor and coastline are able to be maintained on a real-time basis, taking account of ship movement recorded on the compulsory AIS (Automatic Information System) beacons. Maintenance of this real-time topology allows for easy detection of potential collisions, as well as real-time bathymetric estimations, necessary to prevent ship grounding in highly tidal environments. The system, based on previous research into kinetic Voronoi diagrams, as well as development of a completely new graphical engine, is now in commercial production, where its advantages over simpler twodimensional models without automatic collision and grounding detection are becoming evident. Other applications are readily envisaged, and will be addressed in the near future.
A COMPARITIVE STUDY USING GEOMETRIC AND VERTICAL PROFILE FEATURES DERIVED FROM AIRBORNE LIDAR FOR CLASSIFYING TREE GENERA
Authors: Ko C. , Sohn G. , Remmel T. K.
Published: October 2012

Abstract. We present a comparative study between two different approaches for tree genera classification using descriptors derived from tree geometry and those derived from the vertical profile analysis of LiDAR point data. The different methods provide two perspectives for processing LiDAR point clouds for tree genera identification. The geometric perspective analyzes individual tree crowns in relation to valuable information related to characteristics of clusters and line segments derived within crowns and overall tree shapes to highlight the spatial distribution of LiDAR points within the crown. Conversely, analyzing vertical profiles retrieves information about the point distributions with respect to height percentiles; this perspective emphasizes of the importance that point distributions at specific heights express, accommodating for the decreased point density with respect to depth of canopy penetration by LiDAR pulses. The targeted species include white birch, maple, oak, poplar, white pine and jack pine at a study site northeast of Sault Ste. Marie, Ontario, Canada.
SEMI-AUTOMATIC CO-REGISTRATION OF PHOTOGRAMMETRIC AND LIDAR DATA USING BUILDINGS
Authors: Armenakis C. , Gao Y. , Sohn G.
Published: October 2012

Abstract. In this work, the co-registration steps between LiDAR and photogrammetric DSM 3Ddata are analyzed and a solution based on automated plane matching is proposed and implemented. For a robust 3D geometric transformation both planes and points are used. Initially planes are chosen as the co-registration primitives. To confine the search space for the plane matching a sequential automatic building matching is performed first. For matching buildings from the LiDAR and the photogrammetric data, a similarity objective function is formed based on the roof height difference (RHD), the 3D histogram of the building attributes, and the building boundary area of a building. A region growing algorithm based on a Triangulated Irregular Network (TIN) is implemented to extract planes from both datasets. Next, an automatic successive process for identifying and matching corresponding planes from the two datasets has been developed and implemented. It is based on the building boundary region and determines plane pairs through a robust matching process thus eliminating outlier pairs. The selected correct plane pairs are the input data for the geometric transformation process. The 3D conformal transformation method in conjunction with the attitude quaternion is applied to obtain the transformation parameters using the normal vectors of the corresponding plane pairs. Following the mapping of one dataset onto the coordinate system of the other, the Iterative Closest Point (ICP) algorithm is then applied, using the corresponding building point clouds to further refine the transformation solution. The results indicate that the combination of planes and points improve the co-registration outcomes.
PROBABILISTIC FEATURE MATCHING APPLIED TO PRIMITIVE BASED REGISTRATION OF TLS DATA
Authors: Hullo J.-F. , Thibault G. , Grussenmeyer P. , Landes T. , Bennequin D.
Published: October 2012

Abstract. Many industrial applications require dense point clouds of the installations. Acquisition of the rooms, filled with many objects, of an industrial scene leads to many Terrestrial Laser Scanner (TLS) stations. A precise registration of all the per-station point clouds is crucial for the required accuracy of 1-2 cm of final data. Targets and tachometry, current best practice for registration, slows down the survey and limits the number of campaigns. Indoor geolocation system are faster but do not reach the final required accuracy. Otherwise, 3D primitives can be automatically extracted from the dense point clouds and possibly used for registration. In a four step primitive-based registration, Acquisition – Reconstruction – Matching – Solving, the matching is crucial. This article presents a probabilistic test for 3D lines matching using a priori distributions of approximated transformations. The stochastic model of approximated transformations and resulting uncertain lines is introduced. A test is performed on a real dataset of an industrial scene and the results are analysed. Improvements of the presented test and matching framework are also discussed.
EFFICIENT AND GLOBALLY OPTIMAL MULTI VIEW DENSE MATCHING FOR AERIAL IMAGES
Authors: Irschara A. , Rumpler M. , Meixner P. , Pock T. , Bischof H.
Published: October 2012

Abstract. A variety of applications exist for aerial 3D reconstruction, ranging from the production of digital surface models (DSMs) and digital terrain models (DTMs) to the creation of true orthophoto and full 3D models of urban scenes that can be visualized through the web. In this paper we present an automated end-to-end workflow to create digital surface models from large scale and highly overlapping aerial images. The core component of our approach is a multi-view dense matching algorithm that fully exploits the redundancy of the data. This is in contrast to traditional two-view based stereo matching approaches in aerial photogrammetry. In particular, our solution to dense depth estimation is based on a multi-view plane sweep approach with discontinuity preserving global optimization. We provide a fully automatic framework for aerial triangulation, image overlap estimation and dense depth matching. Our algorithms are designed to run on current graphics processing units (GPUs) which makes large scale processing feasible at low cost. We present dense matching results from a large aerial survey comprising 3000 aerial images of Graz and give a detailed performance analysis in terms of accuracy and processing time.
SUB-SURFACE GROWING AND BOUNDARY GENERALIZATION FOR 3D BUILDING RECONSTRUCTION
Authors: Kada M. , Wichmann A.
Published: October 2012

Abstract. The automatic reconstruction of 3D building models from airborne point cloud data is still an ongoing research topic. Especially for complex roof shapes, the identification of sub-shapes, the generation of roof boundaries and the construction to well-shaped and topologically correct models remains only partially solved. In this paper, a 3D building reconstruction methodology that is based on the notion of sub-surface growing as a means for point cloud segmentation of planar surfaces is introduced. In contrast to conventional surface growing, the segmentation process continues below other surfaces. As a result, the segments grow larger, their number decrease and the adjacency relations between them become more distinct, thus allowing stricter rules to help identify and differentiate between the root types of the roof sub-shapes and their composition to complex roof structures. In conjunction with a constructive solid modeling approach, the model construction is significantly simplified, as the generation of primitives from sub-surface segments is straightforward and their combination to complex shapes can be much easier derived from their interrelations. In the second part of the paper, a boundary generalization approach is presented that allows generating building and segment outlines with regularized shapes from given point sets. Together with sub-surface growing, its usage in the reconstruction of flat roof office buildings is shown. The models are constructed in layers in a bottom-up fashion, each one being the result of a flat sub-surface segment with a generalized boundary, where the regularization rules of one layer are propagated to the next in order to gain well-shaped buildings. A discussion on the so far achieved results and future developments concludes the paper.