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Moreira J.M.M.,University of Gävle | Moreira J.M.M.,University of Extremadura | Nex F.,3D Optical Metrology Unit | Agugiaro G.,3D Optical Metrology Unit | And 2 more authors.
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives | Year: 2013

The paper reviews the state-of-the-art in 3D city models and building block generation, with a description of the most common solutions and approaches. Then the digital reconstruction and comparison of LoD1 and LoD2 building models obtained with commercial packages and using different input data are presented. As input data, a DSM at 1m resolution derived from a GeoEye-1 stereo-pair, a DSM from an aerial block at 50 cm GSD and a LiDAR-based DSM at 1m resolution are used. The geometric buildings produced with each dataset are evaluated with respect to some ground-truth measurements but also compared between them. Problems such as the quality of the input DSM, the accuracy of the necessary vector datasets containing the building footprints, the flexibility of the approaches and the potentialities of each dataset will be discussed. As reconstruction of the building models is largely influenced by the quality of the building footprints, which may be out-of-date or slightly shifted with respect to the employed DSMs/DTMs, an in-house method is being developed to derive them starting from the produced DSMs.

Agugiaro G.,3D Optical Metrology Unit | Agugiaro G.,AIT Austrian Institute of Technology
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives | Year: 2014

More and more cities are moving towards the creation and adoption of three-dimensional virtual city models as a means for data integration, harmonisation and storage. To this purpose, CityGML is an international standard conceived specifically as information and data model for semantic city models at urban and territorial scale. The automatic building reconstruction process, up to the Level of Detail 2 (LoD2) can be achieved nowadays nearly completely automatically and with a high degree of accuracy, provided that high quality input data (e.g. a dense DSM obtained from LiDAR or dense stereo-matching with 10÷15 pt/m2 or better) are provided. This paper deals indeed with the creation of a CityGML-compliant, LoD2 city model starting from sub-optimal datasets and tries to address some of the issues tied with the use of sub-standard data - which however, represents a quite common case in "real life". As study area, a part of the city of Trento, in the northern Alpine region of Italy, was chosen and contains about 2300 buildings of different typology, use and construction year. Only existing datasets were gathered and used.

Poli D.,European Commission - Joint Research Center Ispra | Angiuli E.,European Commission - Joint Research Center Ispra | Remondino F.,3D Optical Metrology Unit
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives | Year: 2010

WorldView-2 (WV-2) is DigitalGlobe's latest very high resolution optical sensor. Launched on October 8, 2009, and fully operational since January 5, 2010, it flies along a sun-synchronous orbit at an altitude of 770km. The sensor is able to acquire panchromatic imagery at 0.46m ground resolution (0.52m at 20° off-nadir) and multispectral images in eight spectral bands at 1.8m resolution. In addition to the four typical multispectral bands (blue, green, red, near infrared), the sensors scans the coastal (400-450nm), yellow (585-625nm), red edge (705-745nm) and near infrared-2 (860-1040nm) bands. Stereo images can be planned thanks to the ability of the sensor to rotate off-nadir up to +/-45°. This paper describes the preliminary analysis on WV-2 carried out at the EU Joint Research Center (JRC) in Ispra (Italy) by the ISFEREA Team of the Institute for the Protection and Security of the Citizen (IPSC), and in collaboration with the Bruno Kessler Foundation (FBK) in Trento (Italy). The purpose of the study is to evaluate the radiometric and geometric properties of the sensor and its potentials for 3D information extraction. The images used for the analysis are a stereopair over North-West Italy, where ISFEREA is establishing a testfield. The radiometry of the images is evaluated through different methods, including the estimation of the noise level (standard deviation of the digital number) in homogeneous and non-homogeneous areas. The images are oriented with RPC-based approach: using some GCP (ground control points), the given Rational Polynomial Coefficients (RPC) are improved with an affine transformation to compensate residual systematic errors. For automatic 3D information assessment, a Digital Surface Model (DSM) is generated with the SAT-PP software package and 3D building models are extracted semi-automatically with the CyberCity-Modeler (CCM) package. The methodology and preliminary results are described and discussed.

Barazzetti L.,Polytechnic of Milan | Remondino F.,3D Optical Metrology Unit | Scaioni M.,Polytechnic of Milan
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives | Year: 2010

Automation in 3D reconstruction involves mainly two tasks: (i) image orientation and (ii) 3D scene reconstruction. Nowadays, automation in (i) can be considered solved for aerial photogrammetric projects, but a general and commercial solution is still pending in case of close-range image blocks. Here, the complexity and diversity of the network geometry make the automatic identification of the image correspondences a challenging task. In this paper we present a methodology to automatically orient a set of targetless close-range images taken with a calibrated camera and the following creation of 3D models with a multi-image matching algorithm. Several real cases, comprehending free-form objects (e.g. bas-relieves, decorations, etc.), building facades and images taken with UAVs are reported and discussed. Lastly, some preliminary results on a methodology for markerless camera calibration are presented.

Barazzetti L.,Polytechnic of Milan | Remondino F.,3D Optical Metrology Unit | Scaioni M.,Polytechnic of Milan
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives | Year: 2010

The article presents a powerful and automated methodology to extract accurate image correspondences from different kinds of closerange image blocks for their successive orientation with a bundle adjustment. The actual absence of a commercial solution able to automatically orient markerless image blocks confirms the still open research in this field. The developed procedure combines different image processing algorithms and robust estimation methods in order to obtain accurate locations and a uniform distribution of tie points in the images. We demonstrate the capabilities and effectiveness of this method with several tests on closed or open sequences and sparse blocks of images captured by a standard frame (pinhole) camera, but also spherical images. An accuracy evaluation of the achieved 3D object coordinates with photogrammetric bundle techniques is also presented.

Barazzetti L.,Polytechnic of Milan | Remondino F.,3D Optical Metrology Unit | Scaioni M.,Polytechnic of Milan | Brumana R.,Polytechnic of Milan
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives | Year: 2010

The paper presents a procedure for the automatic orientation of image blocks captured by UAV-borne cameras. Disregarding the availability or absence of GPS/INS data, the method is able to extract a set of manifold tie points to be used as observations in a photogrammetric bundle adjustment. Complex image configurations and scenes can be dealt with, encompassing the use of convergent imagery, strong perspective deformations, lighting changes and so on. Tie points are extracted among image pair combinations by exploiting operators like SIFT and SURF, which are invariant with respect to scale variations and rotations as well. Then all image pairs are linked together to compute a global bundle adjustment. In order to speed up the process, a coarse-to-fine approach can be used, integrated to the creation of a visibility map that limits the selection of image pairs to be analysed. Some tests on different UAV blocks are reported and discussed, showing the potential of this procedure to obtain the orientation of all images in a fully automated way.

Nex F.,3D Optical Metrology Unit | Remondino F.,3D Optical Metrology Unit
Applied Geomatics | Year: 2014

Unmanned aerial vehicle (UAV) platforms are nowadays a valuable source of data for inspection, surveillance, mapping, and 3D modeling issues. As UAVs can be considered as a low-cost alternative to the classical manned aerial photogrammetry, new applications in the shortand close-range domain are introduced. Rotary or fixed-wing UAVs, capable of performing the photogrammetric data acquisition with amateur or SLR digital cameras, can fly in manual, semiautomated, and autonomous modes. Following a typical photogrammetric workflow, 3D results like digital surface or terrain models, contours, textured 3D models, vector information, etc. can be produced, even on large areas. The paper reports the state of the art of UAV for geomatics applications, giving an overview of different UAV platforms, applications, and case studies, showing also the latest developments of UAV image processing. New perspectives are also addressed. © 2014 Società Italiana di Fotogrammetria e Topografia (SIFET).

Menna F.,3D Optical Metrology Unit | Remondino F.,3D Optical Metrology Unit | Battisti R.,3D Optical Metrology Unit | Battisti R.,University of Trento | Nocerino E.,Parthenope University of Naples
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011

3D imaging systems are widely available and used for surveying, modeling and entertainment applications, but clear statements regarding their characteristics, performances and limitations are still missing. The VDI/VDE and the ASTME57 committees are trying to set some standards but the commercial market is not reacting properly. Since many new users are approaching these 3D recording methodologies, clear statements and information clarifying if a package or system satisfies certain requirements before investing are fundamental for those users who are not really familiar with these technologies. Recently small and portable consumer-grade active sensors came on the market, like TOF rangeimaging cameras or low-cost triangulation-based range sensor. A quite interesting active system was produced by PrimeSense and launched on the market thanks to the Microsoft Xbox project with the name of Kinect. The article reports the geometric investigation of the Kinect active sensors, considering its measurement performances, the accuracy of the retrieved range data and the possibility to use it for 3D modeling application. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

Manferdini A.M.,University of Bologna | Remondino F.,3D Optical Metrology Unit
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2010

One of the most significant consequences of the introduction of digital 3D modeling in the Cultural Heritage field is the possibility to use 3D models as highly effective and intuitive means of communication as well as interface to share and visualize information collected in databases. Due to the usual complexity of architectural and archaeological artifacts or sites, their digital models need be subdivided in sub-components and organized following semantic definitions in order to facilitate data retrieval. This paper outlines a methodology to semantically segment complex reality-based 3D models, annotate information and share the results within online open-source tools. The segmentation stage to subdivide and organize 3D models is based on both automated and manual methods, giving priority to automated procedures that can ease and speed these steps but not neglecting the user intervention to achieve accurate results. The segmented 3D models are then visualized in web-based systems to allow data access to a wider range of users and enlarge knowledge. The methodology is presented and tested on large and complex reality-based 3D models of architectural and archaeological heritage structures. © 2010 Springer-Verlag Berlin Heidelberg.

Agugiaro G.,3D Optical Metrology Unit | Poli D.,Vermessung AVT ZT GmbH | Remondino F.,3D Optical Metrology Unit
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives | Year: 2012

Today the use of spaceborne Very High Spatial Resolution (VHSR) optical sensors for automatic 3D information extraction is increasing in the scientific and civil communities. The 3D Optical Metrology (3DOM) Unit of the Bruno Kessler Foundation (FBK) in Trento (Italy) has collected stereo VHSR satellite imagery, as well as aerial and terrestrial data over Trento, with the aim to create a complete data collection with state-of-the-art datasets for investigations on image analysis, automatic digital surface model (DSM) generation, 2D/3D feature extraction, city modelling and data fusion. The testfield region covers the city of Trento, characterised by very dense urban (historical centre), residential and industrial areas, and the surrounding hills and steep mountains (approximate height range 200-2100 m) with cultivations, forests and bare soil. This paper reports the analysis conducted in FBK on the VHSR spaceborne imagery of Trento testfield for 3D information extraction. The data include two stereo-pairs acquired by WorldView-2 in August 2010 and by GeoEye-1 in September 2011 in panchromatic and multispectral mode, together with their original Rational Polynomial Coefficients (RPC), and the position and description of well distributed ground points. For reference and validation, a DSM from airborne LiDAR acquisition is used. The paper gives details on the project and the dataset characteristics. The results achieved by 3DOM on DSM extraction from WorldView-2 and GeoEye-1 stereo-pairs are shown and commented.

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