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    VIDENTE - 3D Visualization of Underground Infrastructure using Handheld Augmented Reality

    Gerhard Schall1, Dieter Schmalstieg1

    1 Institute of Computer Graphics and Vision, Graz University of Technology, Inffeldgasse 16a, 8010 Graz, Austria, {schall|[email protected]}, Tel: +43-(0)316-873-5011, Fax: -5050

    Sebastian Junghanns2

    2 GRINTEC GmbH, Anzengrubergasse 6, 8010 Graz, Austria, [email protected], Tel: +43-(0)316-383706-0, Fax: -20

    Introduction This chapter outlines a research project called Vidente following the vision of registered 3D visualization of underground networks on handheld devices in real-time. Towards this aim, technology from interdisciplinary fields such as computer graphics, augmented reality, geographic information systems (GIS) and satellite navigation needs to be addressed. We highlight aspects of the Vidente system targeted on water systems operated by utilities from the water supply sector, which are already completely relying on their geo-databases for day-to-day operation of their assets. However, there is a noticeable gap between desktop GIS technology available in the office and access to this information in the field. To fill this gap, we propose to provide field workers with an intuitive three-dimensional visualization of the local underground network infrastructure using outdoor handheld augmented reality (AR) as depicted in Figure 1. The focus is on a next-generation mobile GIS system for utilities as well as telecommunication companies, supporting mobile workforces in the complete life cycle of water infrastructure, thus revolutionizing traditional planning, operation, maintenance, on-site inspection, fault management and decision-making. The project significantly advances mobile GIS in water engineering. Moreover, common field tasks concerning maintenance and operation are accomplished more efficiently while reducing unintended damage and increasing general safety on site. The system is intended to equip professionals, practitioners, water resources engineers, managers and decision makers working in water related arenas, utilities from the water sector, water boards and other government agencies with available information and advanced information technology tools to assist in on-site applications to geohydrological and environmental problems of urban waters.

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    Figure 1: View through the AR display deployed outdoors. In the image a second AR user with a handheld AR display can be seen. Underground infrastructure as well as wire frame building models are shown.

    Current state of field information systems of utilities Mobile GIS extends Geographic Information Systems beyond the office to the field by incorporating technologies such as mobile devices, wireless communication and positioning systems. Mobile GIS enables accurate, real-time decisions, on-site capturing, storing, manipulating, analyzing and displaying of geospatial data. As an extension, the ability to interact with location based information was added to mobile GIS applications and services. Such services play an important role for on-site analysis, aiding critical decision making with information about underground infrastructure assets. Industrial mobile GIS can already be deployed in low end computing systems such as PDAs [ArcPad07]. Current commercial mobile GIS products include, for example, FieldWorker, GPSPilot, Fugawi, Todarmal, ESRI ArcPad, MapInfo, MapXmobile, Smallworld Field Information System or MapFrame FieldSmart. FieldWorker is used for exchanging information with mobile workers. GPSPilot and Fugawi are examples of traditional 2D maps intended for navigation. Todarmal provides the possibility to create map content (points, lines and 2D polygons) online in a layered manner. ESRI ArcPad is intended for managing point type GIS data, where digital photos can be attached to point information. The ArcPad comes with a support for routing with street map data. MapInfo MapXmobile is a development tool similar to ArcPad, intended for creating map applications. Smallworld Field Information System and MapFrame FieldSmart represent mobile GIS particularly aiming at needs of utilities, hence supporting a process-driven approach. Both applications support straightforward handling of extensive utility network datasets and efficient data reconciling with version-managed and longterm-transaction-based back-office GIS.

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    New methods for mobile GIS offered by VIDENTE Handheld augmented reality extends traditional 2D or 3D visualizations by overlaying registered visualizations over video footages. There is a clear trend away from bulky computer equipment towards handheld devices which are more lightweight and already socially accepted [Wagner03]. Over the last years only few ultra mobile PC installations have been used for handheld AR deployed especially in outdoor conditions, predominantly in urban areas [Schmalstieg05] [Schall07] [Veas08]. They replace laptop-based AR systems or backpack-based solutions [Feiner97] [Thomas98]. Although these systems can run simple visualizations, it is impossible to manage the large data sets needed for on-site monitoring using AR methods. In relation to the previous section, handheld devices exist that have been used in the exploration of GIS data. These include ARVINO, exploring viticulture data [King05], and Priestnall simple landscape visualization system [Priestnall06]. Examples of interaction tools with underground infrastructure using handheld AR are described in section “Visualization techniques” [Schall08a] [Schall08b] (see Figure 2 and Figure 3). Among others these tools comprise data retrieval capabilities, redlining functionality to annotate the geospatial assets and a virtual excavation tool to improve depth perception of complex underground infrastructure. Especially useful was the planning tool, which allows for visualizing projected assets superimposed over the real world. Moreover, the position of the projected asset can be changed on-site interactively.

    Furthermore, Vidente can contribute to Horizontal Directional Drilling (HDD), which provides an efficient, economical system for installing underground lines and pipe without disturbing the surface environment. In such a task, a drill head with a miniature transmitter travels through the ground on a prescribed path, transmitting updated data to a computer on the drilling equipment. The operator monitors the input and adjusts the direction and movement of the drill head to avoid other underground infrastructure and efficiently reach the prescribed end location. After expanding the initial path, the cable is then pulled through the underground path providing a perfect path for water lines, but also power, telephone of fiber optic cables and lines. Underground Horizontal Directional Drilling is especially cost-effective compared to old- fashioned trenching, with its need for landscape repair and the additional problems of relocating

    Figure 2. Vidente: handheld augmented reality device. Figure 3. Vidente: presentation of the subsurface infrastructure information at the client device (screenshot) (data courtesy of Salzburg AG).

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    and avoiding other underground systems. Underground Horizontal Directional Drilling can benefit from a technology like Vidente by allowing to visualize existing underground infrastructure registered in 3D with the real environment. Thus, giving visual assistance to the operator to support the monitoring process by X-Ray visualization views beneath the ground. An even more challenging but promising goal is to replace true surveying tasks with AR, which up to now required the use of specialized equipment such as a tachymeter. For example, users wishing to document the path of a projected pipe after on-site inspection of the best route previously had to record a sequence of waypoints using conventional surveying, and then import these waypoints into the geo-database in the planning office to create a digital asset. We suggest using 3D interaction techniques to allow workers to create new digital geo-referenced assets. For example, a worker can survey a series of waypoints by intersecting the ray from a “virtual laser pointer” with the digital elevation model. Accuracy concerns notwithstanding, it may be an order of magnitude faster to record several such waypoints from one location rather than having to physically follow the path of the planned pipe. However, the creation of some objects may require triangulation from at least two physical locations for sufficiently precise input, as suggested by [Höllerer01] and [Piekarski01]. Explanation of change in process Technological developments in imaging and vision technology, geoinformatics, computer graphics and augmented reality (AR) are promising more and more capabilities not only in visualizing the real world but also in spatial data acquisition and management. Recent years showed a strong trend towards handheld devices such as (ruggedized) Ultra Mobile PCs, PDAs or even smart phones, since these devices are already equipped with sensors necessary for AR. Furthermore, mobile GIS extends geographic information systems from the office to the field by incorporating the before mentioned technologies. Mobile GIS enables workers for on-site capturing, storing, manipulating, analysing and displaying of geospatial data and therefore provides clear benefits for mobile workforces. Current trends of mobile field systems are dominated by quality and completeness control in the field, seamless dataflow between office and field and vice versa, no redundancies in data and workflows. With the appro