ISPRS Scientific Initiative. Summaries of projects funded for 2014

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1 ISPRS Scientific Initiative Summaries of projects funded for 2014 Benchmark on High Density Image Matching for DSM Computation PI: Norbert Haala, Institute for Photogrammetry, University of Stuttgart Stereo-matching for the automatic generation of elevation data from aerial images was originally introduced more than two decades ago. These approaches used feature based matching algorithms to avoid problems at regions with very limited texture. Meanwhile, state-of-the-art digital airborne cameras provide imagery of good dynamic and signal-to-noise-ratio, which supports pixel-wise matching especially for low-texture areas. Furthermore, recent matching approaches cope with the general ambiguity of such a per-pixel measurement by introducing additional constraints. Socalled global algorithms explicitly formulate the matching problem under the assumption of smooth surfaces. This global optimization problem can be implemented very efficiently using recursive algorithms like scanline optimization. A very popular and well performing stereo method frequently applied for the processing of aerial images is semi-global matching (SGM). Also triggered by these developments, software tools for image based generation of 3D point clouds and dense Digital Surface Models (DSM) are currently developed by a number of research institutes and photogrammetric software vendors. In order to document the progress also in photogrammetric data processing benchmarks have proven to be extremely useful. Well known examples which measure the performance of state-of-the-art matching algorithms are the Middlebury Stereo Vision Page (Scharstein, & Szeliski 2002) or the benchmark on multi-view stereo reconstruction (Seitz et.al. 2006). These benchmarks provide general purpose datasets through a platform, where results can be uploaded to automatically yield quality metrics of the respective approach. While these projects emerged from the Computer Vision community, the test on the performance of photogrammetric digital airborne camera systems (Cramer, 2010) was organized by the German society of Photogrammetry, Remote Sensing and Geoinformation (DGPF). Also in view of the ongoing software developments, the proposed initiative aims to evaluate the potential of photogrammetric 3D data capture from automatic image matching. Basic scope is the evaluation of 3D point clouds and DSM produced from aerial images with different software systems. Such a comparative evaluation should provide a platform for software developers to demonstrate the state-of-the-art of their ongoing developments. Furthermore, it should help potential users like National Mapping and Cadastral agencies (NMCAs), which consider a state-wide-generation of high quality DSMs to understand the applicability of such tools while triggering further developments based on their needs.

2 TIC The Tracking and Imaging Challenge 2015 PI: Stephan Winter, University of Melbourne TIC the Tracking and Imaging Challenge 2015 is aiming at stimulating research and excellent work at the interface of two distinct disciplines working with spatial data the Computer Vision & Image Processing and the GIScience & spatial computing community. This is going to be achieved by requiring that two types of data, namely trajectory data and images, are linked in innovative ways. The challenge is on purpose broad and open to allow for unorthodox and novel applications and methods. It is expected that TIC will enhance the visibility of ISPRS research and events.

3 ISPRS Benchmark on Urban Object Detection and 3D Building Reconstruction PI: Markus Gerke, ITC, University of Twente, Enschede One of the major topics in photogrammetry is the automated extraction of urban objects from data acquired by airborne sensors. What makes this task challenging is the very heterogeneous appearance of objects like buildings, streets, trees and cars, in particular in data having a very high-resolution, which leads to high intra-class variance while the inter-class variance is low. It turns out that in this context progress is hampered by the missing availability of state-of-the-art test data for research, either captured with aerial cameras or airborne laserscanners. Only few research groups have access to data of highest quality and resolution and usually these data sets are difficult to be shared between groups due to copyright regulations etc. Thus, as many groups do not have access to state-ofthe-art data; the majority of scientific publications evaluate novel methods only on a very limited amount of data, and different groups use different data sets. Results are therefore hardly comparable, which, we believe, significantly slows down scientific progress. The ISPRS WG III/4 benchmark on Urban Object Detection and 3D Building Reconstruction aims at resolving this problem. It offers state-of-the-art data sets which can be used by interested researchers in order to test their own methods and algorithms on urban object classification and building reconstruction. Results can be submitted at any time and are compared to manually annotated 2D and 3D reference data using a standard evaluation framework. Despite significant efforts by the working group officials, the preparation of benchmark data is very expensive in terms of time and money. Although various data sets have been promised or made available to the WG officials, limited financial resources severely retard the release of new benchmark data. Funding through the ISPRS scientific initiative will allow us to heavily increase 2D and 3D reference data annotation efforts. We believe that this will enable us to at least double the amount of completely annotated benchmark data until summer 2015.

4 Status of Global Geospatial Information PI: Gottfried Konecny, Leibniz University Hannover The ISPRS WG IV-2 activity is based on an agreement between ISPRS and UNGGIM signed in December 2011 to cooperate on a survey of the global status of geospatial information, signed between the 2011 ISPRS President Orhan Altan and the 2011 Director of UNGGIM Paul Cheung. The ISPRS WG IV-2 was established on the initiative of the 2012 ISPRS President Chen Jun with the applicants of Leibniz University Hannover and the UNGGIM Secretariat in New York to be responsible for designing, issuing and evaluating a questionnaire to the UN member countries on the status of geospatial information and its infrastructure. Reports on the preliminary results were given at the UNGGIM 2 Conference in New York in August 2012, at the ISPRS Congress in Melbourne in August 2012, at the UNGGIM Forum in Qatar in February 2013, at the UNGGIM3 Conference in Cambridge in July 2013, at the UNRCC-Americas in New York in August 2013 to solicit a wide interest of the UN member states in the effort. The WG IV-2 also held meetings at Interexpo Geosibir in Novosibirsk in April 2013, at the Geospatial Forum in Rotterdam in May 2013 and at the Scanex Conference in Moscow in October 2013 to address the issues of non-governmental data providers, such as Google, Microsoft and others. With the exception of Cambridge in July 2013, ISPRS has so far not been involved in financial support of these efforts. Based on this activity the 2014 Project applied for, needs to concentrate on a further in depth analysis of the collected data and to augment the information from other sources. Supplementary information has been received by UN Country reports and from other sources.

5 A new benchmark dataset for multi-platform very high resolution photogrammetry PI: Francesco Nex, Fondazione Bruno Kessler (FBK), Trento Airborne high resolution oblique imagery systems and RPAS/UAVs are very promising technologies that will keep on influencing the development of geomatics in the future years closing the gap between terrestrial and classical aerial acquisitions. These two platforms are also a promising solution for National Mapping and Cartographic Agencies (NMCA) as they allow to derive complementary and sometimes better mapping information. Although the interest for the registration and integration of aerial and terrestrial data is constantly increasing, only few works have been truly performed on this topic. Several investigations still need to be undertaken concerning algorithms ability for automatic co-registration, accurate point cloud generation and feature extraction from multi-platform image data. One of the biggest obstacles is the non-availability of reliable and free datasets to test and compare new algorithms and procedures. In particular, a complete benchmark on oblique, UAV and terrestrial images together has never been realized before. For these reasons, this scientific initiative will use the grant provided by ISPRS mainly to collect and share state-of-the-art multi-sensor data over an urban area, specifically: oblique airborne images, UAV-based images and terrestrial images of some selected buildings. In addition, reference points and Terrestrial Laser Scanning (TLS) data will be acquired to enable a thorough evaluation of image orientation and calibration methods, as well as of dense image matching results. Interested researchers will be encouraged to use the image data (from one platform, or a merge) to participate in the orientation benchmark through submitting 3D coordinates of independent check points distributed all over the area. Results from image dense matching will be evaluated using cross-sections, best fitting and high-resolution TLS point clouds. Although the benchmark will focus on the mentioned tasks, other research, e.g. on radiometric properties or semantic scene analysis using those images can be accommodated. Through the provision of this dataset to the photogrammetric, computer vision and adjacent communities, we expect that the value of those state-of-the-art platform s data can be evaluated more objectively. Last not least, the visibility of ISPRS across domains will be promoted and its connection with other societies (e.g. EuroSDR) and communities will be strengthened.

6 Development of a Curriculum for The African Geospatial Sciences Institute (AGSI) PI: Ian Dowman, University College London The primary objective of this project is to support capacity building in North Africa. North Africa has been subject to severe disruption in recent years and there is an urgent need for the construction of infrastructure and for the services of trained geospatial professionals and technicians. The African Geospatial Sciences Institute (AGSI) is a non profit organisation registered in Germany which is supported by industry, government and academia. The objective of AGSI is to accelerate the geospatial capacity development in North Africa by providing the facilities for geospatial projects and management training to regional government employees, university graduates, private individuals and companies. Funds from the ISPRS Scientific Initiative would be used to develop a curriculum for AGSI based on the requirements of the region and using the expertise of ISPRS working groups. ISPRS could make a significant contribution to developing the curriculum which could then be used in similar initiatives elsewhere. The project involves ISPRS Working Groups, ISPRS Regional Members, cognate societies and local organisations. The project will last for six months and will involve a survey of potential stakeholders in North Africa, drafting a curriculum on the basis of the returns from the survey and then discussing this at a workshop to be held in Tunis in May The initial curriculum will concentrate on vocational geospatial training, emphasizing practical, project-based work. Learning-by doing is the priority and whilst all participants will be encouraged to continue with a more formal education, there will also be support for anyone who wants to start his own business. The curriculum will take account of the resources available and particularly look at how low cost equipment such as UAVs and low cost or open source software can be used. The emphasis will be on training and education which is fit for purpose in the region and which will allow those completing the course to work efficiently and effectively. ISPRS will benefit from enhancement of the international standing and from the opportunity to contribute significantly to the development of geospatial science in North Africa. The project will also bring together ISPRS members in the region to work on a substantive regional project.