BARBER. 18th International Symposium of CIPA

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1 BARBER. 18th International Symposium of CIPA Conference Reports 18TH INTERNATIONAL SYMPOSIUM OF CIPA THE 18TH International Symposium of the International Committee for Architectural Photogrammetry (CIPA) was held from 18th to 21st September 2001 in Potsdam, Germany. Potsdam provided an attractive and appropriate setting for a symposium on architectural photogrammetry. Located close to the site where Albrecht Meydenbauer laid down the foundations of architectural photogrammetry before the start of the last century, Potsdam itself has numerous examples of photogrammetry at work within many of the construction and renovation projects ongoing in the town. The symposium attendance was in excess of 250 people, including representatives from academia and the commercial sector. Although Germany provided the majority of delegates, English was the symposium language. This year s symposium took the theme of traditional and modern methods for the surveying and documentation of historic buildings, monuments and sites. The opening ceremony included the usual welcoming speeches with the symposium then taking the classic mixture of plenary, technical and poster sessions, allowing a wide range of projects to be presented. A small commercial presence allowed delegates to view up-to-date equipment and systems. A major part of the symposium concerned the use of terrestrial laser scanners, with vendors and users keen to share their experiences both in and out of the presentations. These mixed experiences emphasised the need for laser scanning to form an important component of the forthcoming ISPRS Commission V symposium, due to be held in September 2002 in Corfu, Greece. Other technical sessions included simple methods in architectural photogrammetry, integration of survey techniques and digital image processing. The plenary sessions dealt with the wider aspects of CIPA activity, most notable being the session on the morning of Wednesday 19th September entitled Bridging the gap between the information user and information provider. Improved partnership between organisations such as CIPA, the Getty Conservation Institute and the International Council on Monuments and Sites ( ICOMOS) was proposed in an attempt to fill some of the holes highlighted in the vital link between information user and provider. Many of the points regarding the need for documentation were echoed throughout the technical sessions. The organisers provided an enjoyable welcome reception and the opportunity to take part in technical excursions to Potsdam and Berlin. The symposium provided a clear overview of some of the difficulties involved in architectural documentation and covered its chosen theme well. Much is expected of the next CIPA symposium to be held in Antalya, Turkey in October D. M. BARBER University of Newcastle Photogrammetric Record, 17(99),

2 SMART. 48th Photogrammetric Week 48TH PHOTOGRAMMETRIC WEEK THE 48TH Photogrammetric Week was held at the University of Stuttgart, Germany from 24th to 28th September Although most of the presentations were linked to Z/I Imaging products, speakers from other major vendors, such as LH Systems and Inpho, also contributed, to give a balanced view of the industry and where it was heading. The week started with an optional one-day workshop on the preceding Sunday, followed by the main conference, for which each day consisted of presentations in the mornings, demonstrations by Z/I Imaging and University of Stuttgart staff in the afternoons, and receptions in the evenings. The workshop on digital aerial camera systems was a great success, attended by over 90 delegates who were enthusiastic enough to give up their weekend to learn about the theory and practicalities of this rapidly developing technology. The four main sessions were run in parallel, in both German and English, with the themes of digital imaging, concepts of image collection and evaluation, empirical accuracy investigations and the application of potential digital systems. The tutorials were supported by high quality PowerPoint presentations containing useful animations explaining the physics of digital theory. It was envisaged that airborne digital cameras would take some of the high resolution satellite market. It was noted that in 1997 there were only 14 cloud-free days over Germany. With this figure dropping to eight days in 1998 an opportunity is seen for digital cameras to respond quicker by flying beneath any high cloud cover. Other advantages of digital cameras were the better 12-bit grey-scale recording, giving better shadow penetration and the ability to enhance the image at post-processing stage, a realtime QA which would allow immediate reflying and the ability to collect multispectral data at the same time. The main disadvantages were seen as the handling of high data volumes, the expense and time of data exchange and the cost of the systems currently on offer. Why would existing analogue camera operators want to pay perhaps twice as much for a digital system which might have problems integrating with existing systems and might incur the cost of additional customised software? The host, Professor D. Fritsch, expressed the opinion that it could be up to three years before a reliable system could be bought off the shelf and that film cameras could be around for another 10 to 30 years. Fritsch also believes that CMOS sensors will replace CCDs within the next five years. As an observation, most of the digital cameras available only provide the equivalent of a 150 mm wideangle lens and although the demand for orthorectified city centre imagery is likely to increase, the vendors have no apparent plans to fill this potential gap in the market. Each delegate was supplied with a copy of the lecture notes and a CD of the PowerPoint presentations, a very useful source of reference material for the future. The Photogrammetric Week covered three main topics, namely sensor integration for image data collection, data fusion and automation, and web photogrammetry and e-business. The first presentation, which made a lasting impression, was given by G. Thiele from the European Astronaut Centre. He was a key member of the crew of the space shuttle, Endeavour, launched in February 2000 to collect 506 Photogrammetric Record, 17(99), 2002

3 SMART. 48th Photogrammetric Week data for the Shuttle Radar Topography Mission (SRTM). The objective was to collect data for a three-dimensional model of the earth between 60 N and 57 Sat a grid spacing of 30 m, with heights to an accuracy of 10 m rms. The mission collected almost all of the data required twice over, totalling 14 terabytes, at an amazing rate of 270 Mb s 1. It will be two years before all of the data is processed and the maps become available. Apart from the technical aspects, his personal impressions of the mission and the video of the team at take-off and going about their daily routine in orbit were of great interest. The slides showing the thin tenmile band of atmosphere which surrounds the Earth and in which all life exists brought home the fragility of life on our planet and the responsibility we all have to preserve it. Thiele s presentation was followed by a series of introductory overviews of topics to be covered later in the week. S. Volz, from the University of Stuttgart, gave an overview of the NEXUS project which aims to have a prototype system running by the summer of 2002, offering a single platform for all location-based applications. The field of wireless-based applications introduced a whole new vocabulary of terms and acronyms which will no doubt all become familiar to us as the technology develops. The next paper, by H. Heier, covered the use of the Z/I Imaging Digital Modular Camera (DMC) in today s workflow. The digital aerial camera is the missing link in a fully digital photogrammetric system and its introduction will improve the efficiency of existing flowlines. The solution offered by Z/I Imaging is not dependent on an INS/DGPS system to reconstitute the image and the resulting perspective projection will be compatible with much of the existing photogrammetric equipment. The session on sensor integration for data collection started with a presentation by M. Cramer giving an overview of the application of GPS/INS systems, their performance and limitations. He emphasised that the systems, driven by the lidar and digital camera applications, were now mature technology but there was still need for improvement. Because of the lack of redundancy there was still a need to reduce errors in large-scale applications by running the data through an aerial triangulation package. B. Reid from Applanix followed with the good news for all of us with shrinking aircraft, that future hardware would be smaller and hopefully lighter. The session continued on the Tuesday morning with presentations from other non-z/i Imaging vendors. J. Kremer from IGI started with a presentation on the IGI CCNS and AEROcontrol INS/GPS systems. The hardware, post-processing software and accuracies obtained were very similar to the Applanix system presented earlier, although the physical size of the hardware appeared bulkier. The highly successful mission planning software is now available on Microsoft Windows and is able to operate on a wide variety of mapping formats and in 70 local mapping grid systems. After a paper by A. Hinz on the Z/I Imaging DMC, which covered much of the material given in the workshop, P. Fricker from LH Systems presented his paper on the progress of the ADS40 digital camera system. Following successful trials with customers in Japan and Italy, it is planned to produce five units this year. They plan to support more tests using the data with ORIMA to eliminate parallaxes and also carry out trials with ERDAS on image processing. The postprocessing of the raw imagery is still very time consuming but is improving. As Photogrammetric Record, 17(99),

4 SMART. 48th Photogrammetric Week the ADS40 was developed with DLR, it was appropriate that the next speaker, G. Neukum, presented results from the DLR HRSC camera after one year of operations. The camera has now captured more than 150 major cities to very high standards and the company sees the camera competing with the high resolution aerial and satellite imagery markets. S. Scherer presented a paper on RapidEye, a family of optical satellites. This is a very interesting and exciting project that plans to have a constellation of four mini-satellites in orbit by 2004 providing daily coverage of Europe and North America to a 6 5 m ground resolution. They aim to have just a small number of customers in the agriculture, cartography and disaster management fields; they are considering producing a 20 m DEM with 5 m rms accuracy as well as a 1: scale orthophotomap product which would be updated annually. Much of the hardware for the project is being produced in the UK. In a similar niche of the market, A. Baudoin from SpotImage gave the next presentation on the proposed Pleiades system that will follow SPOT 5 and is due for launch in SpotImage will be getting less government funding in the future and, to remain competitive, Pleiades will be one sixth of the weight of SPOT 5 at one third of the cost. Six satellites are planned, two with optical sensors and four with radar. The optical satellites will provide 0 7 m panchromatic and 2 0 m multispectral resolution and will be in competition with similar American satellites. C. Brenner gave an informative presentation on city model generation. This was a major topic at the previous Photogrammetric Week but the process is now more refined and the computations are much quicker; the resulting interpretation of a multitude of different roof topologies was most impressive. The next main topic, Data Fusion and Automation, started with presentations from the three main producers of automatic aerial triangulation packages, Z/I Imaging, LH Systems and Inpho, who gave papers on the latest enhancements to their own software. All are able to accept INS/GPS data as control and, having listened to their customers, all have improved the tools to aid error detection. The LH Systems ORIMA5 system is now able to handle data from push-broom aerial scanners. B. Mercer presented a comparison of lidar and InSAR technologies. In his opinion there is a place for both technologies, and the two should be looked at as complementary rather than as competitors. InSAR had the price advantage in sparsely vegetated non-core urban areas whilst lidar gave better bald-earth DEM performance in forest and urban areas. A very interesting paper was presented by M. Holm from Inpho on an integrated approach to orthoimage production. He stated that most elements of the process are at present automated but the Complete OBject Reconstruction Application (COBRA) software will allow full automation using a process of global matching. The input will be imagery and control and the output a seamless colour balanced true orthoimage. The main problem at the moment is the computer power required to undertake the processing but the end results are impressive. A 3 2 km example made up of 50 images demonstrated that the software was able to produce a true orthophotograph with just the tops of trees and buildings in their true ground position displayed. A digital surface model (DSM) was also produced as a by-product. Development of this product needs to be monitored as it offers 508 Photogrammetric Record, 17(99), 2002

5 HUNTER. 5th Conference on Optical 3D Measurement Techniques significant labour savings and could become a viable alternative to the stereo solution of updating mapping. The afternoon demonstrations gave the opportunity to look at the Z/I Imaging software in greater detail, get hands-on experience and talk to developers about particular applications. Further one-to-one demonstrations were available afterwards to sort out any outstanding problems. Z/I Imaging took this opportunity to introduce their new automatic aerial triangulation package, Image Station Aerial Triangulation ( ISAT). They have decided no longer to support the Inpho Match-AT package, and their replacement module is a Microsoft Windows-based refinement of the Zeiss PHODIS automatic aerial triangulation package. The workflow follows more traditional aerial triangulation lines and first impressions are that it will be a good robust product. During this period Stuttgart University also demonstrated their NEXUS product for mobile services, as well as the role played by photogrammetry and other data collection devices in providing information for the virtual information towers ( VITs). The other demonstration by the University was on robotics and optical inspections. This was a very impressive demonstration with real-time resections of moving targets computed from a fixed digital camera and a three-dimensional model of a volunteer s head being generated in a few minutes. The evening receptions were a very welcome break from the information overload of the day and they gave an opportunity to network with other users and talk about their own experiences, successes and occasional disappointments with the various products. In summary it was a well-organised and well-balanced week with good quality papers and demonstrations. Your reporter came away with a positive feeling that photogrammetry was alive and has an exciting future ahead of it. A. T. SMART Ordnance Survey 5TH CONFERENCE ON OPTICAL 3D MEASUREMENT TECHNIQUES THE FIFTH Optical 3D Measurement Techniques Conference was held in Vienna, Austria between 1st and 4th October In the opening ceremony this meeting was introduced as being unique as a true geodesy conference where practitioners of many disciplines were brought together, including geodesists, photogrammetrists, computer vision experts, mathematicians and engineers. Geodesy here of course reflects German usage, meaning land surveying, or perhaps nowadays geomatics, as a whole. Supporting this introduction was the fact that the conference was sponsored by no less than three professional bodies, namely ISPRS Commission V, IAG Special Commission 4 and FIG Commissions 5 and 6. The meeting was certainly well attended and there was a total of 70 papers and 29 posters with a number of parallel sessions over the three days. There were 170 Photogrammetric Record, 17(99),

6 HUNTER. 5th Conference on Optical 3D Measurement Techniques participants, mainly from Europe but with a handful from North America and an impressive 38 attendees from Asia/Australia. The technology and methods presented at these conferences have seen much change since the first meeting in This year, however, was to see laser scanning at the forefront of discussions. This was reinforced in the opening ceremony where the question was posed as to whether, in the future, laser scanning will achieve the same importance in surveying as GPS now enjoys. In his keynote address, Flesch of TU Wien posed a series of challenges to the optical 3D measurement community to provide useful tools for earthquake research. He highlighted many interesting examples of how optical methods could help with structural monitoring to improve safety under earthquake loads. The first session guided the audience through the latest laser scanning technologies with presentations by equipment manufacturers and end users. The first speaker was Ullrich of Riegl Laser Measurement Systems (Austria), who described the capabilities of their range of scanners. He concluded that no single scanner could be used for all applications and gave some ideas of factors to consider when selecting the most appropriate scanner, starting with aspects such as range and field of view, then going through to the quality issues of mechanical reliability and rugged design. Next came Frolich, of Zoller and Frolich, who talked about his scanners that are unusual in that they use phase measurement rather than pulsed laser or triangulation methods. This allows these scanners to capture data at very high speeds ( points per second) and with high accuracy (8 mm scale error), however only over a short range (10 to 60 m). He also illustrated a very well structured approach to estimating the measurement errors and showed a particularly useful application for surveying railway structures at high speed. Mooyman of Cyra Technologies then took us through the capture, measurement and modelling process employed by the Cyrax laser scanner. He gave a good overview of the technical features of the instrument and its application. Next was Niebuhr who illustrated the features of the Callidus laser scanner. A number of points were of interest, such as the ability of the instrument to calibrate itself over an internal base line. Jacqmin described the MENSI scanner that is based on a triangulation technique and was originally developed by Electricité de France for surveying irradiated environments in nuclear power stations. Wunderlich of TU Munich then provided an overview of where laser scanning fits in with conventional geodetic techniques. There are two conventional survey methods: using polar sensors, for example in tacheometry where explicit distance information is recorded, and using bundle sensors, for example in photogrammetry where a bundle of rays is observed by a camera. The new technology of laser scanning now gives us an instrument that is both a polar and a bundle sensor which requires the convergence of geodetic and photogrammetric ideas in order to gain maximum benefit from these systems. Paar of Joanneum Research gave a review of the use of a long-range laser scanner to monitor rock fall and to map snow cover change in the Austrian Alps. He illustrated a number of image processing techniques that were used to post-process the data. After these opening sessions, the presentations moved to a more balanced mix of optical methods with many practical applications of photogrammetry. The sessions covered mobile mapping, motion and tracking, vision metrology, sensor and object modelling, object reconstruction and visualisation, machine guidance, 510 Photogrammetric Record, 17(99), 2002

7 HUNTER. 5th Conference on Optical 3D Measurement Techniques structured light, airborne laser scanning, multimedia in education and new measurement techniques. These topics, though highly diverse, were linked through the common thread of optical three-dimensional measurement. With the space available here it is not possible to do justice to all those involved in presenting papers. Instead, your reporter has highlighted just a handful of papers that stood out for him. Boochs of i3mainz (Germany) discussed the automatic orientation of arbitrarily arranged images by using coloured spatial tie objects. The colour information was necessary for correspondence analysis and as new metric cameras become available with colour then this may become a practical technique. Wright of the University of Calgary talked about mapping forest fire hotspots in near real time using thermal imaging and GPS. Some smart image processing techniques were used to keep the workload to a minimum and allow fast operation. Gilleron of the Swiss Federal Institute of Technology, Lausanne, described a real-time road data capture system for recording the position of the white centre lines of the main highways in Switzerland. Until now all the street furniture has been located by distance along the road, and the purpose of this project was to add 3D coordinates to this linear system. This involved linking camera and object extraction techniques with GPS in real time. Gruen of the Swiss Federal Institute of Technology, Zurich, described the automatic reconstruction and visualisation of the complex Buddha Tower of Bayon, Cambodia. A number of small-format balloon images were captured on site and were processed semi-automatically to produce an accurate and impressive three-dimensional visualisation. Blais of the National Research Council of Canada described a real-time system for geometrical target tracking for autonomous operation in space. This comprised both laser scanning and photogrammetry systems working together using the best of both to increase accuracy and reliability. Our hosts in Vienna certainly made their guests welcome through some excellent evening activities. A reception at Vienna s impressive Rathaus (City Hall ) and an evening in a typical wine tavern were both memorable occasions. The next meeting in the Optical 3D Measurement series is scheduled to be in Zurich, Switzerland in two years time. G. HUNTER 3D Laser Mapping Ltd Photogrammetric Record, 17(99),