ID: 54292
Title: A new pan-sharpening method using multiobjective particle swarm optimization and the shiftable contourlet transform
Author: Jamal Saeedi, Karim Faez
Editor: George Vosselman
Year: 2011
Publisher: Elsevier, Vol 66, issue 3, May 2011
Source: Centre for Ecological Sciences
Reference: None
Subject: ISPRS Journal of Photogrammetry and Remote Sensing
Keywords: Pan-sharpening, Shiftable contourlet transform, Multiobjective particle swarm optimazation
Abstract: In this paper, a novel approach based on multiobjective particle swarm optimization (MOPSO) is presented for panchromatic (Pan) sharpening of a multispectral (MS) image. This new method could transfer spatial details of the pan image into a high-resolution version of the MS image, while color information from the low-resolution MS image is well preserved. The pan and MS images are locally different because of different resolutions, and therefore we cannot directly combine them in the spatial domain. For this reason, we generate two initial results, which are more appropriate for a weighted combination. First, the pan and the MS images are histogram matched. Then we use the shiftable contourlet transform (SCT) to decompose the histogram-matched pan and MS images. The SCT is a new shiftable and modified version of the contourlet transform. In this step, an algorithm based on the SCT is used to generate two initial results of the high-resolution MS images. Our objective is to produce two modified high-resolution MS images, in which one has high spatial similarity to the pan image and the other one has high radiometric quality in each band. Therefore, we have used two different fusion rules to integrate the high-frequency contourlet coefficients of the pan and MS images to generate two initial results of high-resolution MS image or the pan-sharpened (PS) image. Finally, we can find the optimal PS image by applying the MOPSO algorithm and using the two inital PS results. Specifically, the PS image is obtained via a weighted combination of the two initial results, in which the weights are locally estimated via a multiobjective particle swarm optimization algorithm to generate a PS image with high spatial and radiometric qualities. Based on experimental results obtained, the produced pan-shaped image also has good spectral quality. The efficiency of the proposed method is tested by performing pansharpening of high-resolution (Quickbird and Wordview2) and medium-resolution (Landsat -7 ETM +)datasets. Extensive comparisons with the state-of -the -art pan-sharpening algorithms indicate that our new method provides improved subjective and objective results.
Location: 231
Literature cited 1: None
Literature cited 2: None
ID: 54291
Title: Evaluation of a three-band model for estimating chlorophyll-a concentration in tidal reaches of the Pearl River Estuary, China
Author: Shuisen Chen, Ligang Fang, Hongli Li, Weiqi Chen, Wenrui Huang
Editor: George Vosselman
Year: 2011
Publisher: Elsevier, Vol 66, issue 3, May 2011
Source: Centre for Ecological Sciences
Reference: None
Subject: ISPRS Journal of Photogrammetry and Remote Sensing
Keywords: Chlorophyll-a, Three-band model, Evaluation, Pearl River Estuary, Hyperion remote sensing
Abstract: Accurate assessment of phytoplankton chlorophyll-a (Chla) concentration in turbid waters by means of remote sensing was challenging due to the optical complexity of turbid waters. Recently, a conceptual model containing reflectance in three spectral bands in thered and near-infrared range of the spectrum was suggested for retrieving Chla concentrations in turbid productive waters. The objective of this paper was to evaluate the performance of this three-band model to estimate Chla concentration in the Pearl River Estuary (PRE), China. Reflectance spectra of surface water and water samples were collected concurrently. The samples contained variable Chla (4.80-92.60 mg/m3) and total suspended solids (0.4-55.2 mg/L dry wt). Colored dissolved organic matter (CDOM) absorption at 400 nm was 0.40-1.41 m-1; turbidity ranged from 4 to 25 NTU (Nephelometric Turbidity Units). The three-band model was spectrally calibrated by iterative and least-square linear regression methods to select the optimal spectral bands for the most accurate Chla estimation. Strong linear relationships (R2 = 0.81, RMSE=1.4 mg/m3, N=32) were established between measured Chla and the levels obtained from the calibrated three-band model [R-1 (684)- R-1(690)] x R(718), where R(? ) was the reflectance at wavelength ? . The calibrated three-band model was independently validated (R2 = 0.9521, RMSE = 6.44 mg/m3, N = 16) and applied to retrieve Chla concentrations from the calibrated EO-1 Hyperion reflectance data in the PRE on December 21, 2006. The EO-1 Hyperion-derived Chla concentrations were further validated using synchronous in situ data collected on the same day (R2 = 0.64, RMSE = 2 mg/m3, N =9). The spatial tendency of Chla distribution mapping by Hyperion showed gradually increased concentrations of Chla farther from the river mouths (although decreasing from east to west), which were disturbed by the combination of river outlets and tidal current in Lingding Bay of the PRE. This observation conformed to previous observations and studies, and could reasonably be explained by geographical changes. Also, results indicated that the slope of the three-band regression line decreased as the Chla concentration increased, resulting in the first sensitive band of the three-band model to move towards short wavelengths. These findings validated the rationale behind the conceptual model adn demonstrated the robustness of this algorithm for Chla retrieval from in situ data and the Hyprion satellite sensor in turbid estuarine water of the PRE, China.
Location: 231
Literature cited 1: None
Literature cited 2: None
ID: 54290
Title: Epipolar resampling of linear pushbroom satellite imagery by a new epipolarity model
Author: Mi Wang, Fen Hu, Jonathan Li
Editor: George Vosselman
Year: 2011
Publisher: Elsevier, Vol 66, issue 3, May 2011
Source: Centre for Ecological Sciences
Reference: None
Subject: ISPRS Journal of Photogrammetry and Remote Sensing
Keywords: Photogrammetry, Epipolar resampling, Linear pushbroom satellite imagery
Abstract: This paper presents a practical epipolarity model for high-resolution linear pushbroom satellite images acquired in either along-track or cross-track mode, based on the projection reference plane in object space. A new method for epipolar resampling of satellite stereo imagery based on this model is then developed. In this method, the pixel-to-pixel relationship between the original image and the generated epipolar image is established directly by the geometric sensor model. The approximate epipolar images are generated in a manner similar to digital image rectification. In addition, by arranging the approximate epipolar lines on the defined projection reference plane, a steroscopic model with consistent ground sampling distance and parallel to the object space is thus available, which is more convenient for three-dimensional measurement and interpretation. The results obtained from SPOT5, IKONOS, IRS-P5, and QuickBird stereo images indicate that the generated epipolar imges all achieve high accuracy. Moreover, the vertical parallaxes at check points are at sub-pixel level, thus proving the feasibility, correctness, and applicability of the method.
Location: 231
Literature cited 1: None
Literature cited 2: None
ID: 54289
Title: Image fusion by spatially adaptive filtering using downscaling cokriging
Author: E Pardo-Iguzquiza, V F Rodriguez-Galiano, M Chica-Olmo, Peter M Atkinson
Editor: George Vosselman
Year: 2011
Publisher: Elsevier, Vol 66, issue 3, May 2011
Source: Centre for Ecological Sciences
Reference: None
Subject: ISPRS Journal of Photogrammetry and Remote Sensing
Keywords: Adaptive filtering, Cokriging, Geostatistics, Image fusion, Remote sensing
Abstract: The aim of this paper was to extend the method of downscaling cokriging for image fusion by making the method spatially adaptive in that the filter parameters (cokriging weights) can change across the image. The method can adapt itself to the usual statistical non-homogeneity (spatialy variable mean, variance and correlation length) of a satellite sensor image that covers an area with different spatial patterns of geographical objects or different terrain types. The solution adopted was to estimate the models of covariance and cross-covariances (or semivariograms and cross-semivariograms) by the same procedure as described in Pardo-Iguzquiza et al.( 2006) but with the method applied locally instead of globally. The correct implementation of this local estimation is the key for computational feasibility and prediction efficiency. Two parameters to be taken into account are the grid of locations on which a moving window is centred (local modelling is performed inside this window) and the size of this moving window. With respect to the latter parameter, there is a trade-off between a size small enough to make the procedure locally adaptive and large enough to produce reliable statistical estimates. The computational burden will impose limits to the distance between grid points on which the local moving window is centred. A case study with Landsat ETM+ images was used to show the implementation of the method and the result was evaluated using several statistics widely used for assessing the quality of a fused image, apart from its visual appearance.
Location: 231
Literature cited 1: None
Literature cited 2: None
ID: 54288
Title: Multitemporal laser scanner-based observation of the Mt. Vesuvius crater: Characterization of overall geometry and recognition of landslide events
Author: Arianna Pesci, Giordano Teza, Giuseppe Casula, Fabiana Loddo, Prospero De Martino, Mario Dolce, Francesco Obrizzo, Folco Pingue
Editor: George Vosselman
Year: 2011
Publisher: Elsevier, Vol 66, issue 3, May 2011
Source: Centre for Ecological Sciences
Reference: None
Subject: ISPRS Journal of Photogrammetry and Remote Sensing
Keywords: Terrestrial laser scanning, 3D model, Vesuvius, Landslide, volume
Abstract: Results of observations of the Mt. Vesuvius caldera, carried out by means of terrestrial laser scanning (TLS) in May 2005, October 2006 and June 2009, are reported here. In each survey the whole crater was acquired with 17/20 scans from 6 different viewpoints and the correspoinding digital surface models were generated and registered into the UTM-WGS84 reference frame. In this way, a comparison between the multitemporal models leads to an evaluation of the occurred changes. The deformation maps, i.e. the contouring plots of the differences between the models along the direction of maximum variations, showed a progressive mass loss due to rock-falls from the NE vertical crater wall whose area was about 5000m2. The TLS data also showed the accumulation at the bottom. The volume loss which occurred from 2005 to 2009, was computed by subtraction of volumes defined with respect to reference planes parallel to the caldera walls and was estimated to be 20 300m3. The volume uncertainties due to registration errors, subsampling noise effects, and effects due to choice of the reference plane, were also estimated. Some results were also interpreted on the basis of micro-seismic and meteorological data in order to plan a monitoring technique where seismic signals related to rock -fall and/or signals of intense rainfalls are used as alarms for fast TLS surveys able to characterize the corresponding changes of the caldera walls. The proposed methodology, in particular the simple but effective approach used in the estimation of volume uncertainties, can be applied to each rock slope instability phenomenon, regardless of the particular environment.
Location: 231
Literature cited 1: None
Literature cited 2: None
ID: 54287
Title: Parameter de-correlation and model-identification in hybrid-style terrestrial laser scanner self-calibration
Author: Derel D Lichti, Jacky Chow, Herve Lahamy
Editor: George Vosselman
Year: 2011
Publisher: Elsevier, Vol 66, issue 3, May 2011
Source: Centre for Ecological Sciences
Reference: None
Subject: ISPRS Journal of Photogrammetry and Remote Sensing
Keywords: Laser scanning, Calibration, Error, Modelling, Correlation
Abstract: One of the important systematic error parameters identified in terrestrial laser scanners is teh collimation axis error, which models the non-orthogonality between two instrumental axes. The quality of this parameter determined by self-calibration, as measured by its estimated precision and its correlation with the tertiary rotation angle k of the scanner exterior orientation, is strongly dependent on instrument architecture. While the quality is generally very high for panoramic -type scanners, it is comparably poor for hybrid-style instruments. Two methods for improving the quality of the collimation axis error in hybrid instrument self-calibration are proposed herein: (1) the inclusion of independent observations of the tertiary rotation angle k; and (2) the use of a new colllimation axis error model. Five real datasets were captured with two different hybrid-style scanners to test each method ' s efficacy. While the first method achieves the desired outcome of complete decoupling of the collimation axis error from k, it is shown that the high correlation is simply transferred to other model variables. The second method achieves partial parameter de-correlation to acceptable levels. Importantly, it does so without any adverse, secondary correlations and is therefore that method recommended for future use. Finally, systematic error model identification has been greatly aided in previous studies by graphical analyses of self-calibration residuals. This paper presents results showing the architecture dependence of this techique, revealing its limitations for hybrid scanners.
Location: 231
Literature cited 1: None
Literature cited 2: None
ID: 54286
Title: Using horizontal and vertical building structure to constrain indirect sensor orientation
Author: Markus Gerke
Editor: George Vosselman
Year: 2011
Publisher: Elsevier, Vol 66, issue 3, May 2011
Source: Centre for Ecological Sciences
Reference: None
Subject: ISPRS Journal of Photogrammetry and Remote Sensing
Keywords: Adjustment, bundle, calibration, oblique airborne images, UAV
Abstract: This paper presents a method to integrate linear horizontal, vertical and right-angles scene structures into the bundle adjustment of image sequences. An increasing number of airborne image acquisition systems is available and equipped with non-metric small-or medium-frame cameras and no or insufficiently accurate INS devices. In cases where the data is to be used for the production of geo-spatial data, where a certain accuracy and precision is required, an indirect sensor orientation, possibly including self-calibration, needs to be performed. The idea which led to the presented approach is to reduce the number of GCPs necessary for this task by applying the mentioned scene structures. The method directly uses the linear structures, visible at man-made objects as fictive observations within the adjustment, while self-calibration of intrinsic camera parameters and lens distortion is included as well.
Experiments with two datasets demonstrate that, through this method, only limited GCP information is required to obtain satisfactory results. In fact, in one experiment using oblique images, several scene constraints were provided and only the datum was defined by ground control. The residuals at check points from this setup were similar to the traditional case where several well-distributed GCPs were available in the scene. In the second experiment the ability of this approach to support the bundle adjustment was shown for a UAV dataset. Although no GCP and camera calibration information was available, the visual inspection of adjusted object points and the residuals at horizontal structures confirmed the ability of the method to align an image block with the structure, as embodied in the defined scene constraints. Despite the convincing outcome of the experiments, it needs to be mentioned that some manual work is still involved in defining the constraints. In future work the issue of automation will be addressed.
Location: 231
Literature cited 1: None
Literature cited 2: None
ID: 54285
Title: Detection of impervious surface change with multitemporal Landsat images in an urban-rural frontier
Author: Dengsheng Lu, Emilio Moran, Scott Hetrick
Editor: George Vosselman
Year: 2011
Publisher: Elsevier, Vol 66, issue 3, May 2011
Source: Centre for Ecological Sciences
Reference: None
Subject: ISPRS Journal of Photogrammetry and Remote Sensing
Keywords: Impervious surfaces, Urban-rural frontier, Landsat, QuickBird, Regression analysis
Abstract: Mapping and monitoring impervious surface dynamic change in a complex urban-rural frontier with medium or coarse spatial resolution images is a challenge due to the mixed pixel problem and the spectral confusion between impervious surfaces and other non-vegetation land covers. This research selected Lucas do Rio Verde Country in Mato Grosso State, Brazil as a case study to improve impervious surface estimation performance by the integrated use of Landsat and QuickBird images and to monitor impervious surface change by analyzing the normalized multitemporal Landsat-derived fractional impervious surfaces. This research demonstrates the importance of two-step calibrations. The first step is to calibrate the Landsat-derived fraction impervious surface values through the established regression model based on the QuickBird-derived impervious surface image in 2008. The second step is to conduct the normalization between the calibrated 2008 impervious surface image with other dates of impervious surface images. This research indicates that the per-pixel based method overestimates the impervious surface area in the urban-rural frontier by 50%-60%. In order to accurately estimate impervious surface area, it is necessary to map the fractional impervious surface image and further calibrate the estimates with high spatial resolution images. Also normalization of the multitemporal fractional impervious surface images is needed to reduce the impacts from different environmental conditions, in order to effectively detect the impervious dynamic change in a complex urban-rural frontier. The procedure developed in this paper for mapping and monitoring impervious surface area is especially valuable in urban-rural frontiers where multitemporal Landsat images are difficult to be used for accurately extracting impervious surface features based on traditional per-pixel based classification methods as they cannot effectively handle the mixed pixel problem.
Location: 231
Literature cited 1: None
Literature cited 2: None
ID: 54284
Title: Imaging spectroscopy in soil-water based site suitability assessment for artificial regeneration to Scots pine
Author: Maarit Middleton, Paavo Narhi, Raimo Sutinen
Editor: George Vosselman
Year: 2011
Publisher: Elsevier, Vol 66, issue 3, May 2011
Source: Centre for Ecological Sciences
Reference: None
Subject: ISPRS Journal of Photogrammetry and Remote Sensing
Keywords: Aritificial regeneration, Soil awter content, Understorey plant species, Hyper spectral imaging spectroscopy, Neural network, Receiver operating characteristics curve
Abstract: In a humid northern boreal climate, the success rate of artificial regeneration to Scots pine (Pinus sylvestris L) can be improved by including a soil water content (SWC) based assessment of site suitability in the reforestation planning proces. This paper introduces an application of airborne visible-near-infrared imaging spectroscopic data to identify suitable subregions of forest compartments for the low SWC-tolerant Scots pine. The spatial patterns of understorey plant species communities, recorded by the AISA (Airborne Imaging Spectrometer for Applications) sensor, were demonstrated to be dependent on the underlying SWC. According to the nonmetric multidimensional scaling and correlation results twelve understorey species were found to be most abundant on sites with high soil SWCs. The abundance of bare soil, rocks and abundance of more than ten species indicated low soil SWCs. The spatial patterns of understorey are attributed to time-stability of the underlying SWC patterns. A supervised artificial neural network (radial bias functional link network, probabilistic neural network) approach was taken to classify AISA imaging spectrometer data with dielectric (as a measure volumetric SWC) ground referencing into regimes suitable and unsuitable and unsuitable for Scots pine. The accuracy assessment with receiver operating characteristics curves demonstrated a maximum of 74.1% are under the curve values which indicated moderate success of the NN modelling. The results signified the importance of the training set ' s quality, adequate quantity (>2.43 points/ha) NN algorithm selection over the NN algorithm training parameter optimization to perfection. This methodology for the analysis of site suitability of Scots pine can be recommended, especially when artificial regeneration of former mixed wood Norway spruce (Picea abies L Karst) - downy birch (Betula pubenscens Ehrh.) stands is being considered, so that artificially regenerated areas to Scots pine can be optimized for forestry purposes.
Location: 231
Literature cited 1: None
Literature cited 2: None
ID: 54283
Title: An algorithm for automatically computing the horizontal shift between homologous contours from DTMs
Author: Juan Francisco Reinoso
Editor: George Vosselman
Year: 2011
Publisher: Elsevier, Vol 66, issue 3, May 2011
Source: Centre for Ecological Sciences
Reference: None
Subject: ISPRS Journal of Photogrammetry and Remote Sensing
Keywords: Homologous contours, Non-bijective correspondence
Abstract: The algorithm we present here is useful for measuring the planimetric discrepancy between two models which can be represented by contours. In cartography the paradigm of such models is represented by digital terrain models (DTMs). The measure we propose is based on an area enclosed between homologous contours (two level contours, each belonging to two different models). Our measure is similar to another used previously, although, in the previous studies, the area enclosed between homologous contours was computed manually or it was restricted to particular conditions. The innovation of our approach consists of the automation of the entire process and in the constraint elimination. The main problem to solve before computing the horizontal shift measure is how to determine the area enclosed between homologous contours. This is a problem because there is no bijective correspondence between homologous contours, and therefore the identification of the homologous contours is not a trivial task. Our approach overcomes this difficulty by closing following the limit of the DTM the open contours (the contous which cur the limit of the DTM) and classifying them by the external level. We achieve the automation assisted by the Boolean polygon operations, specifically using the symmetric difference operation. Our algorithm facilitates the computation of accuracy of a DTM by comparison with another and it si applicable in such fields as hydrology (precision estimation of the hydrological features), cartographic generalization, and civil engineering. Finally we use our measure for estimating the planimetric discrepancy between the same streams derived from different DEMs (different sources and precisions).
Location: 231
Literature cited 1: None
Literature cited 2: None
ID: 54282
Title: Extraction and motion estimation of vehicles in single-pass airborne LiDAR data towards urban traffic analysis
Author: Wei Yao, Stefan Hinz, Uwe Stilla
Editor: George Vosselman
Year: 2011
Publisher: Elsevier, Vol 66, issue 3, May 2011
Source: Centre for Ecological Sciences
Reference: None
Subject: ISPRS Journal of Photogrammetry and Remote Sensing
Keywords: Airborne LiDAR, Urban, Motion estimation, Three-dimensional, Traffic monitoring
Abstract: Airborne LiDAR data are characterized by involving not only rich spatial but also temporal information. It is possible to extract vehicles with motion artifacts from single-pass airborne LiDAR data, based on which the motion state and velocity of vehicles can be identified and derived. In this paper, a complete strategy for urban traffic analysis using airborne LiDAR data is presented. An adaptive 3D segmentation method is presented to facilitate the task of vehicle extraction. The method features an ability to detect local arbitrary modes at multi scales, thereby making it particularly appropirate for partitioning complex point cloud data. Vehicle objects are then extracted by a binary classification using object-based features. Furthermore, the motion analysis for extracted vehicles is performed to distinguish between moving and stationary ones. Finally, the velocity is estimated for moving vehicles. The applicability and efficiency of the presented strategy is demonstrated and evaluated on three ALS datasets acquired for the propose of city mapping, where up to 87% of vehicles have been extracted and up to 83% of moving traffic can be recovered together with reasonable velocity estimates. It can be concluded that airborne LiDAR data can provide value-added products for traffic monitoring applications, including vehicle counts, location and velocity, along with traditional products such as building models, DEMs and vegetation models.
Location: 231
Literature cited 1: None
Literature cited 2: None
ID: 54281
Title: Support vector machines in remote sensing: A review
Author: Giorgos Mountrakis, Jungho Im, Caesar Ogole
Editor: George Vosselman
Year: 2011
Publisher: Elsevier, Vol 66, issue 3, May 2011
Source: Centre for Ecological Sciences
Reference: None
Subject: ISPRS Journal of Photogrammetry and Remote Sensing
Keywords: Support vector machines, Review, Remote sensing, SVM, SVMs
Abstract: A wide range of methods for analysis of airborne-derived imagery continues to be proposed and assessed. In this paper, we review remote sensing implementations of support vector machines (SVMs), a promising machine learning methodology. This review is timely due to the exponentially increasing number of works published in recent years. SVMs are particularly appealing in the remote sensing field due to their ability to generalize well even with limited training samples, a common limitation for remote sensing applications. However, they also suffer from parameter assignment issues that can significantly affect obtained results. A summary of empirical results is provided for various applications of over one hundred published works (as of April, 2010). It is our hope that this survey will provide guidelines for future applications of SVMs and possible areas of algorithm enhancement.
Location: 231
Literature cited 1: None
Literature cited 2: None
ID: 54280
Title: Spatio-temporal modellign of informal settlement development in Sancaktepe district, Istanbul, Turkey
Author: Olena Dubovyk, Richard Sliuzas, Johannes Flacke
Editor: George Vosselman
Year: 2011
Publisher: Elsevier, Vol 66, issue 2, March 2011
Source: Centre for Ecological Sciences
Reference: None
Subject: ISPRS Journal of Photogrammetry and Remote Sensing
Keywords: Spatio-temporal analysis, Logistic regression modelling, GIS, Informal settlements, Istanbul
Abstract: In less developed countries, the recent high rates of urban expansion are often associated with the emergence of informal settlements thaty may exaggerate social and environmental problems and impede sustainable development. An enhanced understanding of informal development may, therefore, be a key for future success in its effective management. This paper explores the possibilities offered by progress in Geo-Information Science and spatial modelling to improve understanding of informal settlement development through comprehensive spatio-temporal analyses. First, it investigates spatial and temporal patterns of the growth of the informal settlements in Sancaktepe district of Istanbul between 1990 and 2005. Second, using a logistic regression model, an analysis of the driving forces of informal development and prediction of probable locations of new informal settlements are performed. A list of spatial factors that are correlated to informal development is compiled and used to build six logistic regression models for different time steps between 1990 and 2005. Population density, slope, and proportion of informal settlements in the neighbourhood were found to be the main predictors influencing the spatial development of informal settlements during the study period. The performance of the models is evaluated and validated to identify those which best explain the informal development in the study area. As a result, three models built for 1990-1995 and 1995-2000 were selected to generate probability maps of informal settlement development, showing the likelihood for each location to be informally developed in the future. These results can be used as a basis for the evaluation of the process of informal development in other parts of Istanbul, as well as in other cities and countries. At the same time, the technique may serve as a decision-making tool for urban planners and policy makers.
Location: 231
Literature cited 1: None
Literature cited 2: None
ID: 54279
Title: City model enrichment
Author: Philip D Smart, Jonathan A Quinn, Christopher B Jones
Editor: George Vosselman
Year: 2011
Publisher: Elsevier, Vol 66, issue 2, March 2011
Source: Centre for Ecological Sciences
Reference: None
Subject: ISPRS Journal of Photogrammetry and Remote Sensing
Keywords: Internet/web,Geometry, Georeferencing, Registration, Retrieval
Abstract: The combination of mobile communication technology with location and orientation aware digital cameras has introduced increasing interest in the exploitation of 3D city models for applications such as augumented reality and automated image captioning. The effectiveness of such applications is, at present , severely limited by the often poor quality of semantic annotation of the 3D models. In this paper, we show how freely available sources fo georeferenced Web 2.0 information can be used for automated enrichment of 3D city models. Point referenced names of prominent buildings and landmarks mined from wikipedia articles and from the OpenStreetMaps digital map and Geonames gazetteer have been matched to the 2D ground plan geometry of a 3D city model. In order to address the ambiguities that arise in the assoications between these sources and the city model, we present procedures to merge potentially related buildings and implement fuzzy matching between reference points and building polygons. An experimental evaluation demonstrates the effectiveness of the presented methods.
Location: 231
Literature cited 1: None
Literature cited 2: None
ID: 54278
Title: Aggregation of LoD 1 building models as an optimization problem
Author: R Guercke, T Gotzelmann, C Brenner, M Sester
Editor: George Vosselman
Year: 2011
Publisher: Elsevier, Vol 66, issue 2, March 2011
Source: Centre for Ecological Sciences
Reference: None
Subject: ISPRS Journal of Photogrammetry and Remote Sensing
Keywords: city models, generalization, aggregation, optimization
Abstract: 3D city models offered by digital map providers typically consist of several thousands or even millions of individual building. Those buildings are usually generated in an automated fashion from high resolution cadastral and remote sensing data and can be very detailed. However, not in every application such a high degree of detail is desirable. One way to remove complexity is to aggregate individual buildings, simplify the ground plan and assign an appropriate average building height. This task is computationally complex because it includes the cominatorial optimization problem of determining which subset of the original set of buildings should best be aggregated to meet the demands of an application.
In this article, we introduce approaches to express different aspects of the aggregation of LoD 1 building models in the form of Mixed integer Programming (MIP) problems. The advantage of this approach is that for linear (and some quadratic) MIP problems, sophisticated software exists to find exact solutions (global optima) with reasonable effort. We also propose two different heuristic approaches based on the region growing strategy and evaluate their potential for optimization by comparing their performance to a MIP-based approach.
Location: 231
Literature cited 1: None
Literature cited 2: None