bluuebunny/crossref_metadata_2025 huggingface dataset:
RANDOM FORESTS BASED MULTIPLE CLASSIFIER SYSTEM FOR POWER-LINE SCENE CLASSIFICATION
Authors: Kim H. B. , Sohn G.
Published: September 2012

Abstract. The increasing use of electrical energy has yielded more necessities of electric utilities including transmission lines and electric pylons which require a real-time risk monitoring to prevent massive economical damages. Recently, Airborne Laser Scanning (ALS) has become one of primary data acquisition tool for corridor mapping due to its ability of direct 3D measurements. In particular, for power-line risk management, a rapid and accurate classification of power-line objects is an extremely important task. We propose a 3D classification method combining results obtained from multiple classifier trained with different features. As a base classifier, we employ Random Forests (RF) which is a composite descriptors consisting of a number of decision trees populated through learning with bootstrapping samples. Two different sets of features are investigated that are extracted in a point domain and a feature (i.e., line & polygon) domain. RANSAC and Minimum Description Length (MDL) are applied to create lines and a polygon in each volumetric pixel (voxel) for the line & polygon features. Two RFs are trained from the two groups of features uncorrelated by Principle Component Analysis (PCA), which results are combined for final classification. The experiment with two real datasets demonstrates that the proposed classification method shows 10% improvements in classification accuracy compared to a single classifier.
FOREST SPECIES CLASSIFICATION BASED ON STATISTICAL POINT PATTERN ANALYSIS USING AIRBORNE LIDAR DATA
Authors: Li J. , Hu B. , Noland T. L.
Published: September 2012

Abstract. The paper investigated the effectiveness of point pattern methods in the application of forest species classification using airborne LiDAR data. The forest stands and individual trees in our study area were classified as either shade tolerant or intolerant species. The purpose of adopting the point pattern methods is to develop new features to effectively characterize the pattern of internal foliage distribution of forest stands or individual trees. Three methods including Quadrat Count, Ripley's K-function, and Delaunay Triangulation were applied, and six feature groups were derived for a stand or tree sample. Feature selection was performed based on the derived features in order to find the best ones for the following classification procedure, which was implemented by two supervised and two unsupervised methods. These newly derived features were proved effective for the classification. The highest classification accuracy 97% was achieved at stand level and 90% at individual tree level. The sensitivity of classification accuracy to the number of features used was also investigated in this paper.
VEGETATION CHARACTERISTICS USING MULTI-RETURN TERRESTRIAL LASER SCANNER
Authors: Pirotti F. , Guarnieri A. , Vettore A.
Published: September 2012

Abstract. Distinguishing vegetation characteristics in a terrestrial laser scanner dataset is an interesting issue for environmental assessment. Methods for filtering vegetation points to distinguish them from ground class have been widely studied mostly on datasets derived from airborne laser scanner, less so for terrestrial laser scanners (TLS). Recent developments in terrestrial laser sensors – further ranges, faster acquisition and multiple return echoes for some models – has risen interest for surface modelling applications. The downside of TLS is that a typical dataset has a very dense cloud, with obvious side-effects on post-processing time. Here we use a scan from a sensor which provides evaluation of multiple target echoes providing with more than 70 million points on our study area. The area presents a complex set of features ranging from dense vegetation undergrowth to very steep and uneven terrain. The method consists on a first step which subsets the original points to define ground candidates by taking into account the ordinal return number and the amplitude. Next a custom progressive morphological filter (closing operation) is applied on ground candidate points using multidimensional (varying resolutions) grids and a structure element to determine cell values. Vegetation density mapping over the area is then estimated using a weighted ration of point counts in the tri-dimensional space over each cell. The overall result is a pipeline for processing TLS points clouds with minimal user interaction, producing a Digital Terrain Model (DTM), a Digital Surface Model (DSM) a vegetation density map and a derived canopy height model (CHM). Results on DTM show an accuracy (RMSE) of 0.307 m with a mean error of 0.0573 m compared to a control DTM extracted from Terrascan's progressive triangulation procedure. The derived CHM was tested over 30 tree heights resulting in 27 trees having an absolute error value below 0.2 m (three were just below 0.7 m).
RECONSTRUCTION OF CONSISTENT 3D CAD MODELS FROM POINT CLOUD DATA USING A PRIORI CAD MODELS
Authors: Bey A. , Chaine R. , Marc R. , Thibault G. , Akkouche S.
Published: September 2012

Abstract. We address the reconstruction of 3D CAD models from point cloud data acquired in industrial environments, using a pre-existing 3D model as an initial estimate of the scene to be processed. Indeed, this prior knowledge can be used to drive the reconstruction so as to generate an accurate 3D model matching the point cloud. We more particularly focus our work on the cylindrical parts of the 3D models. We propose to state the problem in a probabilistic framework: we have to search for the 3D model which maximizes some probability taking several constraints into account, such as the relevancy with respect to the point cloud and the a priori 3D model, and the consistency of the reconstructed model. The resulting optimization problem can then be handled using a stochastic exploration of the solution space, based on the random insertion of elements in the conﬁguration under construction, coupled with a greedy management of the conﬂicts which efﬁciently improves the conﬁguration at each step. We show that this approach provides reliable reconstructed 3D models by presenting some results on industrial data sets.
ANALYSIS AND APPLICATION OF LIDAR WAVEFORM DATA USING A PROGRESSIVE WAVEFORM DECOMPOSITION METHOD
Authors: Zhu J. , Zhang Z. , Hu X. , Li Z.
Published: September 2012

Abstract. Due to rich information of a full waveform of airborne LiDAR (light detection and ranging) data, the analysis of full waveform has been an active area in LiDAR application. It is possible to digitally sample and store the entire reflected waveform of small-footprint instead of only discrete point clouds. Decomposition of waveform data, a key step in waveform data analysis, can be categorized to two typical methods: 1) the Gaussian modelling method such as the Non-linear least-squares (NLS) algorithm and the maximum likelihood estimation using the Exception Maximization (EM) algorithm. 2) pulse detection method—Average Square Difference Function (ASDF). However, the Gaussian modelling methods strongly rely on initial parameters, whereas the ASDF omits the importance of parameter information of the waveform. In this paper, we proposed a fast algorithm—Progressive Waveform Decomposition (PWD) method to extract local maxims and fit the echo with Gaussian function, and calculate other parameters from the raw waveform data. On the one hand, experiments are implemented to evaluate the PWD method and the results demonstrate its robustness and efficiency. On the other hand, with the PWD parametric analysis of the full-waveform instead of a 3D point cloud, some special applications are investigated afterward.
LASER PULSE VARIATIONS AND THEIR INFLUENCE ON RADIOMETRIC CALIBRATION OF FULL-WAVEFORM LASER SCANNER DATA
Authors: Roncat A. , Lehner H. , Briese C.
Published: September 2012

Abstract. Full-waveform laser scanning extends the information content of "conventional" laser scanning by storing the temporal proﬁle of both the emitted laser pulse and its echoes. This allows for calculating radiometric quantities in addition to the geometric data. This radio- metric information needs to be calibrated in order to enable comparison among ﬂight strips of the same laser scanner campaign and/or different campaigns. Radiometric calibration is aimed at the determination of a calibration constant which contains the parameters of the emitted laser pulse (besides others). All of these parameters are normally treated as constants. In this paper, the sensitivity of the calibration constant to variations of the emitted laser pulse is analysed theoretically by deriving it according to the error propagation law, followed by an empirical analysis carried out on the example of two airborne full-waveform laser scanning campaigns. Both were operated with the same instrument and over the same area on two different dates.
FULLY AUTOMATIC IMAGE-BASED REGISTRATION OF UNORGANIZED TLS DATA
Authors: Weinmann M. , Jutzi B.
Published: September 2012

Abstract. The estimation of the transformation parameters between different point clouds is still a crucial task as it is usually followed by scene reconstruction, object detection or object recognition. Therefore, the estimates should be as accurate as possible. Recent developments show that it is feasible to utilize both the measured range information and the reflectance information sampled as image, as 2D imagery provides additional information. In this paper, an image-based registration approach for TLS data is presented which consists of two major steps. In the first step, the order of the scans is calculated by checking the similarity of the respective reflectance images via the total number of SIFT correspondences between them. Subsequently, in the second step, for each SIFT correspondence the respective SIFT features are filtered with respect to their reliability concerning the range information and projected to 3D space. Combining the 3D points with 2D observations on a virtual plane yields 3D-to-2D correspondences from which the coarse transformation parameters can be estimated via a RANSAC-based registration scheme including the EPnP algorithm. After this coarse registration, the 3D points are again checked for consistency by using constraints based on the 3D distance, and, finally, the remaining 3D points are used for an ICP-based fine registration. Thus, the proposed methodology provides a fast, reliable, accurate and fully automatic image-based approach for the registration of unorganized point clouds without the need of a priori information about the order of the scans, the presence of regular surfaces or human interaction.
PRIMITIVE-BASED BUILDING RECONSTRUCTION BY INTEGRATION OF LIDAR DATA AND OPTICAL IMAGERY
Authors: Zhang W. , Grussenmeyer P. , Yan G. , Mohamed M.
Published: September 2012

Abstract. Airborne LiDAR data and optical imagery are two datasets used for 3D building reconstruction. In this paper, the complementarities of these two datasets are utilized to perform a primitive-based 3D building reconstruction. The proposed method comprises following steps: (1) recognize primitives from LiDAR point cloud and roughly measure primitives' parameters as initial values, and (2) select primitives' features on the imagery, and (3) optimize primitives' parameters by the constraints of LiDAR point cloud and imagery, and (4) represent 3D building model by these optimized primitives. Compared with other modelbased or CSG-based methods, the proposed method is simpler. It only uses the most straightforward features, i.e. planes of LiDAR point cloud and points of optical imagery. The experimental result shows this primitive-based method can accurately reconstruct 3D building model. And it can tightly integrate LiDAR point cloud and optical imagery, that is to say, all primitives’ parameters are optimized with all constraints in one step.
APPROXIMATION OF VOLUME AND BRANCH SIZE DISTRIBUTION OF TREES FROM LASER SCANNER DATA
Authors: Raumonen P. , Kaasalainen S. , Kaasalainen M. , Kaartinen H.
Published: September 2012

Abstract. This paper presents an approach for automatically approximating the above-ground volume and branch size distribution of trees from dense terrestrial laser scanner produced point clouds. The approach is based on the assumption that the point cloud is a sample of a surface in 3D space and the surface is locally like a cylinder. The point cloud is covered with small neighborhoods which conform to the surface. Then the neighborhoods are characterized geometrically and these characterizations are used to classify the points into trunk, branch, and other points. Finally, proper subsets are determined for cylinder ﬁtting using geometric characterizations of the subsets.
DIMENSIONALITY BASED SCALE SELECTION IN 3D LIDAR POINT CLOUDS
Authors: Demantké J. , Mallet C. , David N. , Vallet B.
Published: September 2012

Abstract. This papers presents a multi-scale method that computes robust geometric features on lidar point clouds in order to retrieve the optimal neighborhood size for each point. Three dimensionality features are calculated on spherical neighborhoods at various radius sizes. Based on combinations of the eigenvalues of the local structure tensor, they describe the shape of the neighborhood, indicating whether the local geometry is more linear (1D), planar (2D) or volumetric (3D). Two radius-selection criteria have been tested and compared for ﬁnding automatically the optimal neighborhood radius for each point. Besides, such procedure allows a dimensionality labelling, giving signiﬁcant hints for classiﬁcation and segmentation purposes. The method is successfully applied to 3D point clouds from airborne, terrestrial, and mobile mapping systems since no a priori knowledge on the distribution of the 3D points is required. Extracted dimensionality features and labellings are then favorably compared to those computed from constant size neighborhoods.
HISTORIC BUILDING INFORMATION MODELLING – ADDING INTELLIGENCE TO LASER AND IMAGE BASED SURVEYS
Authors: Murphy M. , McGovern E. , Pavia S.
Published: September 2012

Abstract. Historic Building Information Modelling (HBIM) is a novel prototype library of parametric objects based on historic data and a system of cross platform programmes for mapping parametric objects onto a point cloud and image survey data. The HBIM process begins with remote collection of survey data using a terrestrial laser scanner combined with digital photo modelling. The next stage involves the design and construction of a parametric library of objects, which are based on the manuscripts ranging from Vitruvius to 18th century architectural pattern books. In building parametric objects, the problem of file format and exchange of data has been overcome within the BIM ArchiCAD software platform by using geometric descriptive language (GDL). The plotting of parametric objects onto the laser scan surveys as building components to create or form the entire building is the final stage in the reverse engin- eering process. The final HBIM product is the creation of full 3D models including detail behind the object's surface concerning its methods of construction and material make-up. The resultant HBIM can automatically create cut sections, details and schedules in addition to the orthographic projections and 3D models (wire frame or textured).
RECONSTRUCTING CCTV, BEIJING
Authors: Forcella V. , Mussio L.
Published: September 2012

Abstract. This paper deals with the reconstruction of a building, starting from a point cloud. The shape of this building is a non-stellar concave and multi-connected structure, composed of sowns and chains. A sown is the representation of a horizontal plane formed by dense points. A chain is a planar loop modeled by rare points. CCTV structure is defined only by the three orthogonal Cartesian coordinates. The reconstruction uses a sequence of procedures and the desired output is a consistent 3D model. The first procedure is devoted to attributing points to their voxel and to estimating the three values needed afterwards. The second procedure is devoted to analyzing clusters vertically and horizontally, to preliminarily distinguishing chains from sowns and to generating relational matching. The third procedure is devoted to building closed loops between all chains and all their projections on sowns. The fourth procedure is devoted to connecting points with triangles. The fifth procedure, still being implemented, is devoted to interpolating triangles with triangular splines.
3D WEBGIS AND VISUALIZATION ISSUES FOR ARCHITECTURES AND LARGE SITES
Authors: De Amicis R. , Conti G. , Girardi G. , Andreolli M.
Published: September 2012

Abstract. Traditionally, within the field of archaeology and, more generally, within the cultural heritage domain, Geographical Information Systems (GIS) have been mostly used as support to cataloguing activities, essentially operating as gateways to large geo-referenced archives of specialised cultural heritage information. Additionally GIS have proved to be essential to help cultural heritage institutions improve management of their historical information, providing the means for detection of otherwise hard-to-discover spatial patterns, supporting with computation tools necessary to perform spatial clustering, proximity and orientation analysis. This paper presents a platform developed to answer to both the aforementioned issues, by allowing geo-referenced cataloguing of multi-media resources of cultural relevance as well as access, in a user-friendly manner, through an interactive 3D geobrowser which operates as single point of access to the available digital repositories. The solution has been showcased in the context of "Festival dell’Economia" (the Fair of Economics) a major event recently occurred in Trento, Italy and it has allowed visitors of the event to interactively access an extremely large repository of information, as well as their metadata, available across the area of the Autonomous Province of Trento, in Italy. Within the event, an extremely large repository was made accessible, via the network, through web-services, from a 3D interactive geobrowser developed by the authors. The 3D scene was enriched with a number of Points of Interest (POIs) linking to information available within various databases. The software package was deployed with a complex hardware set-up composed of a large composite panoramic screen covering a horizontal field of view of 240 degrees.
SPACE MOVING OBJECTS SPATIO-TEMPORAL MODELING AND VISUALIZATION
Authors: Qing X. , Yang Z. , Baoming Z. , ChaoZhen L.
Published: September 2012

Abstract. In future, 3 Dimensions Geographic information System (3D GIS) should support the temporal dimensions modeling and manage all three components efficiently. It is difficult for current 3D Visualization software to deal with temporal phenomenon. An spatio-temporal data model is proposed in this paper, this data model take geometry-data, space moving data and inside action data of the object into account comprehensively. And accomplish holistic modeling of geometry, action, and moving data of the object..
DEVELOPING PARAMETRIC BUILDING MODELS – THE GANDIS USE CASE
Authors: Thaller W. , Krispel U. , Havemann S. , Redi I. , Redi A. , Fellner D. W.
Published: September 2012

Abstract. In the course of a project related to green building design, we have created a group of eight parametric building models that can be manipulated interactively with respect to dimensions, number of ﬂoors, and a few other parameters. We report on the commonalities and differences between the models and the abstractions that we were able to identify.
AUTOMATIC ARCHITECTURAL STYLE RECOGNITION
Authors: Mathias M. , Martinovic A. , Weissenberg J. , Haegler S. , Van Gool L.
Published: September 2012

Abstract. Procedural modeling has proven to be a very valuable tool in the ﬁeld of architecture. In the last few years, research has soared to automatically create procedural models from images. However, current algorithms for this process of inverse procedural modeling rely on the assumption that the building style is known. So far, the determination of the building style has remained a manual task. In this paper, we propose an algorithm which automates this process through classiﬁcation of architectural styles from facade images. Our classiﬁer ﬁrst identiﬁes the images containing buildings, then separates individual facades within an image and determines the building style. This information could then be used to initialize the building reconstruction process. We have trained our classiﬁer to distinguish between several distinct architectural styles, namely Flemish Renaissance, Haussmannian and Neoclassical. Finally, we demonstrate our approach on various street-side images.
GENERATING ALTERNATIVE PROPOSALS FOR THE LOUVRE USING PROCEDURAL MODELING
Authors: Calogero E. , Arnold D.
Published: September 2012

Abstract. This paper presents the process of reconstructing two facade designs for the East wing of the Louvre using procedural modeling. The ﬁrst proposal reconstructed is Louis Le Vau's 1662 scheme and the second is the 1668 design of the "petit conseil" that still stands today. The initial results presented show how such reconstructions may aid general and expert understanding of the two designs. It is claimed that by formalizing the facade description into a shape grammar in CityEngine, a systematized approach to a stylistic analysis is possible. It is also asserted that such an analysis is still best understood in the historical context of what is known about the contemporary design intentions of the building creators and commissioners.
VIRTUAL RECONSTRUCTION OF THE ALMAQAH TEMPLE OF YEHA IN ETHIOPIA BY TERRESTRIAL LASER SCANNING
Authors: Lindstaedt M. , Mechelke K. , Schnelle M. , Kersten Th.
Published: September 2012

Abstract. In autumn 2009 the Almaqah Temple of Yeha in Ethiopia has been recorded by terrestrial laser scanning and digital photogrammetry in cooperation between the Sana'a Branch of the Orient Department of the German Archaeological Institute and the HafenCity University Hamburg. The temple dates from the 7th Century BC and is one of the best preserved buildings of Sabaean architecture in Africa. As a basis for all future project works a geodetic network was established in UTM-coordinates by GPS measurements. The geodata collected will form the basis for all future work on the temple. The deformations of the facades were determined for restoration issues and the existing parts of the temple were modelled by meshing (3D triangulation). Using the scanned point cloud and a technical analysis of the building the Propylon, which is no longer existent today, was virtually reconstructed. In future, the data will also be included in the master plan for touristic development of the region of Axum and Yeha in northern Ethiopia.
AN APPROACH TOWARDS THE CONSTRUCTION OF A DIGITAL ATLAS FOR THE DOCUMENTATION OF CLOISTER AND COURTYARDS IN ASCOLI PICENO
Authors: Ippoliti E. , Rossi D. , Meschini A. , Moscati A.
Published: September 2012

Abstract. The following article aims to present the results of a research experience that defines a geographic information system oriented at the architecture of closed areas of cloisters and courtyards of the historic center of Ascoli Piceno. This experimentation is part of the scenery of documentation's activities for the management and the enhancement of urban environmental improvements through the use of integrated technologies closed and open source. Therefore the main object of the analysis was the architectural one, in its different, articulated and individual features, but always considered in relation to the same geographical location, in this case the urban space, consequently focused not only on the object itself, but also on the relationship between this and any other similar ones. In this sense, the tested geographic information system is intentionally hybrid. We wanted to check the possibility of binding different shape and nature data to the "map" by structuring in a well organized manner different information – drawings, videos, photos, 3D, etc.. – in order to realize a GIS that would allow to analyze the architecture of cloisters and courtyards both in its relations to the urban context and in its specific spatial qualities.
RECONSTRUCTION OF 3D VECTOR MODELS OF BUILDINGS BY COMBINATION OF ALS, TLS AND VLS DATA
Authors: Boulaassal H. , Landes T. , Grussenmeyer P.
Published: September 2012

Abstract. Airborne Laser Scanning (ALS), Terrestrial Laser Scanning (TLS) and Vehicle based Laser Scanning (VLS) are widely used as data acquisition methods for 3D building modelling. ALS data is often used to generate, among others, roof models. TLS data has proven its effectiveness in the geometric reconstruction of building façades. Although the operating algorithms used in the processing chain of these two kinds of data are quite similar, their combination should be more investigated. This study explores the possibility of combining ALS and TLS data for simultaneously producing 3D building models from bird point of view and pedestrian point of view. The geometric accuracy of roofs and façades models is different due to the acquisition techniques. In order to take these differences into account, the surfaces composing roofs and façades are extracted with the same algorithm of segmentation. Nevertheless the segmentation algorithm must be adapted to the properties of the different point clouds. It is based on the RANSAC algorithm, but has been applied in a sequential way in order to extract all potential planar clusters from airborne and terrestrial datasets. Surfaces are fitted to planar clusters, allowing edge detection and reconstruction of vector polygons. Models resulting from TLS data are obviously more accurate than those generated from ALS data. Therefore, the geometry of the roofs is corrected and adapted according to the geometry of the corresponding façades. Finally, the effects of the differences between raw ALS and TLS data on the results of the modeling process are analyzed. It is shown that such combination could be used to produce reliable 3D building models.
APERO, AN OPEN SOURCE BUNDLE ADJUSMENT SOFTWARE FOR AUTOMATIC CALIBRATION AND ORIENTATION OF SET OF IMAGES
Authors: Pierrot Deseilligny M. , Clery I.
Published: September 2012

Abstract. IGN has developed a set of photogrammetric tools, APERO and MICMAC, for computing 3D models from set of images. This software, developed initially for its internal needs are now delivered as open source code. This paper focuses on the presentation of APERO the orientation software. Compared to some other free software initiatives, it is probably more complex but also more complete, its targeted user is rather professionals (architects, archaeologist, geomophologist) than people. APERO uses both computer vision approach for estimation of initial solution and photogrammetry for a rigorous compensation of the total error; it has a large library of parametric model of distortion allowing a precise modelization of all the kind of pinhole camera we know, including several model of fish-eye; there is also several tools for geo-referencing the result. The results are illustrated on various application, including the data-set of 3D-Arch workshop.
AUTOMATED AND ACCURATE ORIENTATION OF COMPLEX IMAGE SEQUENCES
Authors: Barazzetti L. , Remondino F. , Scaioni M.
Published: September 2012

Abstract. The paper illustrates an automated methodology capable of finding tie points in different categories of images for a successive orientation and camera pose estimation procedure. The algorithmic implementation is encapsulated into a software called ATiPE. The entire procedure combines several algorithms of both Computer Vision (CV) and Photogrammetry in order to obtain accurate results in an automated way. Although there exist numerous efficient solutions for images taken with the traditional aerial block geometry, the complexity and diversity of image network geometry in close-range applications makes the automatic identification of tie points a very complicated task. The reported examples were made available for the 3D-ARCH 2011 conference and include images featuring different characteristics in terms of resolution, network geometry, calibration information and external constraints (ground control points, known distances). In addition, some further examples are shown, that demonstrate the capability of the orientation procedure to cope with a large variety of block configurations.
PERFORMANCE EVALUATION OF A STRUCTURE AND MOTION STRATEGY IN ARCHITECTURE AND CULTURAL HERITAGE
Authors: Roncella R. , Re C. , Forlani G.
Published: September 2012

Abstract. A large number of strategies and implementations of Structure from Motion (SFM) have been developed; some are being included in photogrammetric software packages. However, finding specific parameters highlighting the efficiency, the accuracy and the reliability of a SFM strategy it is difficult. While most strategies will almost always succeed in any given task (i.e. the orientation of a certain image sequence), judging how good is actually the result, is somehow still an open issue. In the first part of this paper some alternatives and parameters are presented and their pro and cons discussed, with the objective to find out whether there are alternatives to the well-established method of the check points. In the second part, the results of most of the image sequences made available by the workshop organizers, processed with the SFM approach developed by the authors, are presented; results for the sequences where external information (such as ground control points or a DTM) were available are presented in more detail.
3D RECORDING FOR 2D DELIVERING – THE EMPLOYMENT OF 3D MODELS FOR STUDIES AND ANALYSES –
Authors: Rizzi A. , Baratti G. , Jiménez B. , Girardi S. , Remondino F.
Published: September 2012

Abstract. In the last years, thanks to the advances of surveying sensors and techniques, many heritage sites could be accurately replicated in digital form with very detailed and impressive results. The actual limits are mainly related to hardware capabilities, computation time and low performance of personal computer. Often, the produced models are not visible on a normal computer and the only solution to easily visualized them is offline using rendered videos. This kind of 3D representations is useful for digital conservation, divulgation purposes or virtual tourism where people can visit places otherwise closed for preservation or security reasons. But many more potentialities and possible applications are available using a 3D model. The problem is the ability to handle 3D data as without adequate knowledge this information is reduced to standard 2D data. This article presents some surveying and 3D modeling experiences within the APSAT project ("Ambiente e Paesaggi dei Siti d’Altura Trentini", i.e. Environment and Landscapes of Upland Sites in Trentino). APSAT is a multidisciplinary project funded by the Autonomous Province of Trento (Italy) with the aim documenting, surveying, studying, analysing and preserving mountainous and hill-top heritage sites located in the region. The project focuses on theoretical, methodological and technological aspects of the archaeological investigation of mountain landscape, considered as the product of sequences of settlements, parcelling-outs, communication networks, resources, and symbolic places. The mountain environment preserves better than others the traces of hunting and gathering, breeding, agricultural, metallurgical, symbolic activities characterised by different lengths and environmental impacts, from Prehistory to the Modern Period. Therefore the correct surveying and documentation of this heritage sites and material is very important. Within the project, the 3DOM unit of FBK is delivering all the surveying and 3D material to the interdisciplinary partners of the project to allow successive analyses or derivations of restoration plans and conservation policies.
DIGITAL REBIRTH OF THE GREATEST CHURCH OF CLUNY MAIOR ECCLESIA: FROM OPTRONIC SURVEYS TO REAL TIME USE OF THE DIGITAL MODEL
Authors: Landrieu J. , Père C. , Rollier J. , Castandet S. , Schotte G.
Published: September 2012

Abstract. Our multidisciplinary team has virtually reconstructed the greatest church of the Romanesque period in Europe. The third church of the Abbey of Cluny (12th c.) has been destroyed after the French Revolution, leaving only 8% of the building standing. Many documents have been studied, to include the latest archaeological knowledge in the virtual model. Most remains have been scanned for CAD restitution. The mock-up of the church needed 1600 different numerical files, including the scanned pieces and the anastylosis of a Romanesque portal, a Gothic façade and a mosaic pavement. We faced various difficulties to assemble the different elements of the huge building, and to include the digitized parts. Our workflow consisted in generating geometrical shapes of the church, enriched with metadata such as texture, material... The whole mock up was finally exported to dedicated software to run the rendering step. Our work consisted in creating a whole database of 3D models as well as 2D sources (plans, engravings, pictures...) accessible by the scientific community. The scientific perspectives focus on a representation in virtual immersion of the grand church at scale 1 and an access to the digital mock-up through Augmented Reality.
MULTISCALE INTERACTIVE COMMUNICATION: INSIDE AND OUTSIDE THUN CASTLE
Authors: Massari G. A. , Luce F. , Pellegatta C.
Published: September 2012

Abstract. The applications of informatics to architecture have become, for professionals, a great tool for managing analytical phases and project activities but also, for the general public, new ways of communication that may relate directly present, past and future facts. Museums in historic buildings, their installations and the recent experiences of eco-museums located throughout the territory provide a privileged experimentation field for technical and digital representation. On the one hand, the safeguarding and the functional adaptation of buildings use 3D computer graphics models that are real spatially related databases: in them are ordered, viewed and interpreted the results of archival, artistic-historical, diagnostic, technological-structural studies and the assumption and feasibility of interventions. On the other hand, the disclosure of things and knowledge linked to collective memory relies on interactive maps and hypertext systems that provide access to authentic virtual museums; a sort of multimedia extension of the exhibition hall is produced to an architectural scale, but at landscape scale the result is an instrument of cultural development so far unpublished: works that are separated in direct perception find in a zenith view of the map a synthetic relation, related both to spatial parameters and temporal interpretations.
COMPARISON OF TWO STRUCTURE AND MOTION STRATEGIES
Authors: Roncella R. , Re C. , Forlani G.
Published: September 2012

Abstract. Automatic orientation of image sequences in close range photogrammetry is becoming more and more important, not least to maintain a degree of competitiveness with other survey techniques, such as laser scanning. The objective of this paper is to compare two Structure from Motion (SFM) strategies. The previous strategy has been used at our Department for some years already in a wide range of projects and is based on the Harris operator and the fundamental matrix plus the trifocal tensor estimation to filter out the outliers. While it has in most cases performed satisfactorily, the percentage of accepted matches is generally smaller than expected; sometimes this leads to failure of the successful estimation of the trifocal tensor. The second one has only recently been implemented and is still under testing; it is based on the SURF operator and the 5-point relative orientation algorithm. The paper will show a comparison between the two strategies on a series of test cases.
A COMPARISON BETWEEN ACTIVE AND PASSIVE TECHNIQUES FOR UNDERWATER 3D APPLICATIONS
Authors: Bianco G. , Gallo A. , Bruno F. , Muzzupappa M.
Published: September 2012

Abstract. In the field of 3D scanning, there is an increasing need for more accurate technologies to acquire 3D models of close range objects. Underwater exploration, for example, is very hard to perform due to the hostile conditions and the bad visibility of the environment. Some application fields, like underwater archaeology, require to recover tridimensional data of objects that cannot be moved from their site or touched in order to avoid possible damages. Photogrammetry is widely used for underwater 3D acquisition, because it requires just one or two digital still or video cameras to acquire a sequence of images taken from different viewpoints. Stereo systems composed by a pair of cameras are often employed on underwater robots (i.e. ROVs, Remotely Operated Vehicles) and used by scuba divers, in order to survey archaeological sites, reconstruct complex 3D structures in aquatic environment, estimate in situ the length of marine organisms, etc. The stereo 3D reconstruction is based on the triangulation of corresponding points on the two views. This requires to find in both images common points and to match them (correspondence problem), determining a plane that contains the 3D point on the object. Another 3D technique, frequently used in air acquisition, solves this point-matching problem by projecting structured lighting patterns to codify the acquired scene. The corresponding points are identified associating a binary code in both images. In this work we have tested and compared two whole-field 3D imaging techniques (active and passive) based on stereo vision, in underwater environment. A 3D system has been designed, composed by a digital projector and two still cameras mounted in waterproof housing, so that it can perform the various acquisitions without changing the configuration of optical devices. The tests were conducted in a water tank in different turbidity conditions, on objects with different surface properties. In order to simulate a typical seafloor, we used various concentrations of clay. The performances of the two techniques are described and discussed. In particular, the point clouds obtained are compared in terms of number of acquired 3D points and geometrical deviation.
EVALUATING PARAMETERS AFFECTING THE GEOREFERENCING ACCURACY OF TERRESTRIAL LASER SCANNERS
Authors: Miri M. , Varshosaz M.
Published: September 2012

Abstract. Today laser scanning is used as a powerful technology in measuring various simple and complex objects in cultural heritage applications. Depending on the size and the complexity of the objects, these measurements are usually made from several stations. Similar to all other surveying techniques, the coordinate systems of such measurements need to be registered. For this, a number of retro-reflective targets visible from different stations are used. In practice, the target centres are entered in the computations. The accuracy of the target centres, therefore, need to be high or the final object coordinates might not be of sufficient accuracy. A number of factors including the distance between a target and the laser scanner, the direction of the target surface with respect to the laser scanner beams, the intensity and the number of reflected laser beams affect the accuracy of target centres. In this paper, various tests are carried out to examine the effect of such factors on the accuracy of coordinates obtained for the target centres. The results show that the distance to the laser scanner and the angle between a target surface and the corresponding laser beams have considerable effects on the locational accuracy of the targets.
PROJECT PHOTOFLY: NEW 3D MODELING ONLINE WEB SERVICE (CASE STUDIES AND ASSESSMENTS)
Authors: Abate D. , Furini G. , Migliori S. , Pierattini S.
Published: September 2012

Abstract. During summer 2010, Autodesk has released a still ongoing project called Project Photofly, freely downloadable from AutodeskLab web site until August 1 2011. Project Photofly based on computer-vision and photogrammetric principles, exploiting the power of cloud computing, is a web service able to convert collections of photographs into 3D models. Aim of our research was to evaluate the Project Photofly, through different case studies, for 3D modeling of cultural heritage monuments and objects, mostly to identify for which goals and objects it is suitable. The automatic approach will be mainly analyzed.
VIRTUAL MUSEUM APPLICATIONS AND THEIR PUBLIC PERCEPTION IN BOSNIA AND HERZEGOVINA
Authors: Rizvic S. , Sadzak A. , Ramic-Brkic B. , Hulusic V.
Published: September 2012

Abstract. Bosnia and Herzegovina always has been a place where the East meets the West. Over 1000 years, different cultures, religions and civilizations have left their remains in this small country in Western Balkans. Despite all wars and tragic destructions, today in the heart of Sarajevo one can ﬁnd mosques, Catholic and Orthodox churches and Jewish synagogues next to each other and people of different nations and religions living together in mutual respect and friendship. Multiethnic spirit of Bosnia and Herzegovina lives through its cultural heritage. Therefore our task is to ensure its presentation and preservation using Information and Communications Technologies (ICT). So far researchers have achieved signiﬁcant results by creating several virtual museums. In this paper we will present the Museum of Bosnian Traditional Objects, Digital Catalogue of Stecaks and the Virtual Museum of Sarajevo Assassination, giving an overview of the process of creating virtual environments from multiple data sources based on various 3D digitization technologies: some based on traditional 3D modeling, other based on laser scanning or photogrametric techniques.
FROM THE CONTINUOS TO THE DISCRETE MODEL: A LASER SCANNING APPLICATION TO CONSERVATION PROJECTS
Authors: Cardaci A. , Roberti G. M. , Versaci A.
Published: September 2012

Abstract. This paper aims to demonstrate the usage of laser scanning (in particular through a methodology based on the integrated use of the software "FARO© Scene" and "GEXCEL JRC-3D Reconstructor") as a valid alternative to traditional surveying techniques, especially when finalized to the restoration and conservation repair of historical buildings. The need to recreate the complex and often irregular shapes of the ancient architecture, by acting quickly and also being accurate, as well as the subsequent implementation of FEM (Finite Element Method) for structural analysis, have made nowadays the laser scanning survey a very useful technique. The point cloud obtained by laser scanning can be a flexible tool for every need; not a finished product, but a huge database from which it is possible to extract different information at different times. The use of numerical methods in data processing allows wide opportunities of further investigations starting from the fitting equations. The numerical model lends by itself to the possibility of usage in many applications, such as modelization and structure analysis software. This paper presents the case study of the Church of the Assumption and Saint Michael the Archangel, located in Borgo di Terzo (Italy), a magnificent 18th century's building that presented several structural problems like as the overturning of the façade, the cracking of part of the vaulted ceiling. The survey, carried out by laser scanner (FARO© Photon 120) allowed the reconstruction of the exact geometry of the church, offering the basis for performing structural analysis supported by a realistic model (and not an idealized regular one), useful also in the design of repair interventions.
INTERACTIVE 3D LANDSCAPES ON LINE
Authors: Fanini B. , Calori L. , Ferdani D. , Pescarin S.
Published: September 2012

Abstract. The paper describes challenges identified while developing browser embedded 3D landscape rendering applications, our current approach and work-flow and how recent development in browser technologies could affect. All the data, even if processed by optimization and decimation tools, result in very huge databases that require paging, streaming and Level-of-Detail techniques to be implemented to allow remote web based real time fruition. Our approach has been to select an open source scene-graph based visual simulation library with sufficient performance and flexibility and adapt it to the web by providing a browser plug-in. Within the current Montegrotto VR Project, content produced with new pipelines has been integrated. The whole Montegrotto Town has been generated procedurally by CityEngine. We used this procedural approach, based on algorithms and procedures because it is particularly functional to create extensive and credible urban reconstructions. To create the archaeological sites we used optimized mesh acquired with laser scanning and photogrammetry techniques whereas to realize the 3D reconstructions of the main historical buildings we adopted computer-graphic software like blender and 3ds Max. At the final stage, semi-automatic tools have been developed and used up to prepare and clusterise 3D models and scene graph routes for web publishing. Vegetation generators have also been used with the goal of populating the virtual scene to enhance the user perceived realism during the navigation experience. After the description of 3D modelling and optimization techniques, the paper will focus and discuss its results and expectations.
NOVIODUNUM ROMAN FORTRESS. A SURVEY ON A CITY WALL SECTION
Authors: Teodor A. , Teodor E. S. , Florea M. S. , Popescu M. A.
Published: September 2012

Abstract. The paper presents in detail the method used to acquire 2D and 3D representations for the Large Tower of the Roman fortress from Noviodunum (Isaccea, Tulcea County). The available implements were a total station, a digital camera and some software for handling data. The method is not new by any rate, but well fitted to the aims – recording archaeological data on ruined but massif walls, with rough surfaces – and with a limited budget. Lately considered as a low cost procedure, laser scanning is still costly and rare in some East-European countries. Our method, as simple as it is, provides reliable data as a 3D survey, along texture details, at the lowest price, on unfinished fieldwork, preserving and picturing a stage of knowledge about the site and the architectural bodies.
PROCEDURES AND METHODS OF DIGITAL MODELING IN REPRESENTATION DIDACTICS
Authors: La Mantia M.
Published: September 2012

Abstract. At the Bachelor degree course in Engineering/Architecture of the University "La Sapienza" of Rome, the courses of Design and Survey, in addition to considering the learning of methods of representation, the application of descriptive geometry and survey, in order to expand the vision and spatial conception of the student, pay particular attention to the use of information technology for the preparation of design and survey drawings, achieving their goals through an educational path of "learning techniques, procedures and methods of modeling architectural structures." The fields of application involved two different educational areas: the analysis and that of survey, both from the acquisition of the given metric (design or survey) to the development of three-dimensional virtual model.