Rapid Prototyping of Urban River Corridors Using 3D Interactive, Real-time Graphics

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1 Rapid Prototyping of Urban River Corridors Using 3D Interactive, Real-time Graphics Ed MORGAN, Lewis GILL, Eckart LANGE and Daniela ROMANO 1 Introduction URSULA, Urban River corridors and Sustainable Living Agendas, is a complex, interdisciplinary research project with over 30 researchers drawn from the University of Sheffield, University of Bradford, University of Durham, and other partners. The research taking place is driven by the hypothesis that there are significant social, economic and environmental gains to be made by integrated and innovative interventions in urban river corridors. The project has identified several representative case study sites located in Sheffield, UK and for each of these sites a series of changes, or interventions, will be proposed. Each intervention will be based on the combined results of the research conducted within the URSULA project. One of the key objectives for the project is to develop interactive three dimensional (3D) visualisations for the case study sites that will be used to communicate the visual form of the interventions, support preference testing of interventions, enable collaborative design, increase stakeholder participation, and provide assessment of designs against the URSULA hypothesis. In this paper an interactive 3D visualisation is defined as a simulation employing real time 3D graphics to represent the visual form of an area of landscape in which the user can control the viewing position to freely explore all the aspects of the land form. There are many approaches that have been taken to creating computer based landscape visualisations in the landscape planning and design process, from electronic artistic impressions (AL-KODMANY 1999) to 2D photo-montage and 3D landscape visualisation (LANGE 1994). Over the last few years, trends in visualisation, led by developments in graphics hardware and increased need for public consultation within the planning process, have led to the use of interactive 3D models within the design and planning processes for landscape (BISHOP 2005)(LANGE & HEHL-LANGE 2005). Herwig and Paar (2002) explored the concept of using computer game engines to deliver interactive, eye level walkthroughs for landscape visualisations. However, to produce the end result, several stages using different software packages were needed. Simmetry3d (DELIVERANCE SOFTWARE), the software used to provide the interactive visualisations in this study, takes this process a stage further by marrying a landscape design solution with instant interactive walkthroughs based on the technologies used in the computer game industry. The advantage of this system is that it allows for design alterations to be made and these to be available in a walk-through instantaneously. Also, the software can be connected to the Reflex Studio, a University of Sheffield immersive virtual reality (VR) facility.

2 194 E. Morgan, L. Gill, E. Lange and D. Romano Bishop (2005) states there are still many challenges to overcome to create real-time visualisation tools. One barrier to the creation of these interactive models is the production cost of creating visualisations, tied to the complexity of the model (AN 2005). Procedural modelling techniques, utilising 2D GIS vector data, have been used to speed up the production of interactive 3D visualisations (PERRIN, BEAUVAIS & PUPPO 2001)( HOINKES & LANGE, 1995). This paper presents analysis of an efficient methodology developed to create interactive 3D visualisations for use within the URSULA project. It describes two pilot studies which created models of different study sites within Sheffield. Firstly, a central area of the city, Ball Street, was selected and modelled to develop an understanding of modelling methods needed to produce a visualisation of an area. The status quo model was then altered with the introduction of a proposed change to the modelled area, which has been tested in the first of four workshops with the Sheffield Waterways Strategy Group (SWSG). The SWSG is an association of experts who have special interests in the development of the waterways of Sheffield. One of the objectives of the SWSG workshops is to have stakeholders interactively and collaboratively design one of the case study sites from the URSULA project. Secondly, a pilot URSULA research study brought together the researchers to propose various interventions for a different case study site. It took as a starting point a redevelopment proposal by British Land for a brown field plot at Weedon Street, in the Lower Don region of Sheffield. The researchers then converted this proposal into three separate schemes that each increased the focus on the river at the site. A model based on the British Land proposal was created and this was used in a collaborative design process to support the creation of each of the URSULA proposals. 2 Practical Approach/Methods The task of producing interactive 3D visualisations was categorised into three stages for the purposes of this study. A description of these stages is detailed below. 2.1 Software Tools Initially, decisions needed to be made regarding the software tools required to produce visualisations suitable for use within the wider URSULA project. Firstly, there was seen to be a requirement for a general purpose 3D modelling package and whilst there are plenty of alternatives, SketchUp (GOOGLE) was chosen due to its accessibility, ease of use and also due to its configurability (ruby scripting and SDK). Secondly, a real-time visualisation solution was required; although a variety of options were available, Simmetry3d, a software already tailored to rapidly produce interactive landscape visualisations, was chosen as being the most suitable for the URSULA project. It has excellent SketchUp and other data-set compatibility, along with support for VR hardware available to the project. Vegetation within visualisations was seen to be important to URSULA, and this could be accommodated within Simmetry3d by its compatibility with Lenné3d tree and plant models, which are very realistic, species specific models streamlined to work in real-time (LENNÉ3D). Another important feature was the ability to view in both overview (bird s

3 Rapid Prototyping of Urban River Corridors Using 3D Interactive, Real-time Graphics 195 eye) and eye-level modes. Both software applications provide mechanisms for extension which was seen to be important for the research leading on from this initial study. 2.2 Computer Hardware Simmetry3d is a PC, Microsoft Windows software application and has a hardware requirement of an OpenGL compliant graphics card. Also the software has been extended to support quad-buffered stereo output as well as red-blue anaglyph stereo; this allows the interactive 3D visualization to be visited at full body height, within any immersive windows-based virtual reality system, such as that available in the Virtual Reality Laboratory at Sheffield University. Such avatar movement is controlled by the mouse and keyboard or alternatively with a joystick or game-pad. 2.3 Data-sets Using existing data-sets can reduce the time to construct a visualisation model by saving time on laborious survey work and manual modelling. Table 1 shows the type of data-sets identified as being useful and also the specific ones chosen. The choice was dictated by licensing agreements already in place, and also by the compatibility with the software being used. Tab. 1 Identified data-sets and providers. Terrain DTM Ordnance Survey Land-form profile DTM (10m resolution) Aerial photography Cities Revealed (0.2m resolution) Vector land usage data Ordnance Survey MasterMap Photographic Site Survey Manual survey Vegetation models Lenné3d, Simmetry3d Building models Other 3d models SketchUp, Zmapping SketchUp Warehouse, Simmetry3d mesh library Another source of data is that of definitions of interventions to be applied within the visualisation. This data-set could potentially contain changes to all parts of the visualisation model, and needs to fit into the work-flow required to model each different element in the visualisation model. 2.4 Work-flow Once software tools and data-sets had been identified, the operation of integrating one with the other to produce a required visualisation could take place. As the basic starting template for the visualisations, a Digital Terrain Model (DTM) along with draped aerial photography was created in Simmetry3d. Specific features were then added into the area of interest using models derived from vector land-use data, models generated from photographic site surveys and also through the application of design interventions. This

4 196 E. Morgan, L. Gill, E. Lange and D. Romano feature addition part of the work-flow occurred in two ways- by changing the terrain model and its draped texture, and by adding 3D models on top of the terrain model. Table 2 shows a categorisation of the work-flow, and also shows the data-sets required for each category. Tab. 2 Work-flow categorisation. Construct terrain model and drape aerial photo Add built form Add road and paths; width, textures, profile Add river details; channel, water, weirs Add vegetation; species, distribution, size Directly from DTM and aerial photo data-sets Vector data (building footprints); Photos for facade textures Vector data Vector data, photo for weirs Vector data (if available) Figure 1 outlines the work-flow of constructing the visualisation model from the various data-sets. As outlined above and as can be seen in the diagram the feature addition categories within the work-flow were based on vector region data and were used to guide the modelling process. Interventions were introduced manually into the model, and were again guided by vector data (digitised from paper sketches); as a result the introduction of necessary changes was very similar to work-flow used for the construction of the initial model. However, as these changes could potentially affect any part of the model it could, and did in some cases, lead to a manual re-work of parts of the existing model. Figure1. Work-flow Schematic Diagram. 3 Results Both SketchUp and Simmetry3d produced visualisations suitable for use within the URSULA project. SketchUp was quick and easy to use and the models it produced were easily imported into Simmetry3d. The PhotoMatch feature in SketchUp was useful for producing building models from photographs. Simmetry3d was adept at piecing together

5 Rapid Prototyping of Urban River Corridors Using 3D Interactive, Real-time Graphics 197 the various data-sets necessary to produce a visualisation. The ability to use the terrain sculpting tools to edit the imported DTM was useful for creating river channels, for adjusting the terrain with respect to the imported building models, and also with respect to proposed design changes. A valuable feature of Simmetry3d was that it could switch quickly from the design editor to the walk-though visualisation mode which meant that changes could be quickly viewed and assessed at eye level. Two pilot studies of the visualisation approach have been undertaken; the motivation for, and use of the visualisations generated by each being slightly different. A report of each follows. 3.1 Ball Street Bridge Model This was the first model to be constructed and was a chance to use the selected software, data-sets and to develop a streamlined work-flow. Screen shots of this visualisation are shown in Figure 2. Photographs of buildings on the site were used to produce building facade textures, combined with building models generated in SketchUp from vector GIS data. In addition a change to the site was also modelled, which was the introduction of a proposed bridge. Figure 2. Example screen shots of the Ball Street Bridge model This model was utilised in the first of the four aforementioned SWSG workshops, to familiarise the participants with the visualisation approach and hardware. The visualisation was displayed in the Reflex VR Studio to six participants. The first model shown was of the existing area of Sheffield s River Don with no changes from reality. The initial reactions of the participants to the visualisation were very favourable; most of them were familiar with the area being visualised, and were easily able to relate to the visualisation. A more in-depth discussion revealed an issue for some of the participants regarding the vegetation models. They felt that the models were not a close enough representation of the actual species. After the initial exposure to the visualisation, a second model was displayed, identical to the first but with the addition of proposed bridge. This proved to be an excellent aid to

6 198 E. Morgan, L. Gill, E. Lange and D. Romano discussion about the proposal and participants seemed more inclined to focus on the intervention rather than any other aspects of the visualisation. Indeed, even though the bridge had been granted planning permission since 2002, and was well known to the participants most confessed to not having a real idea of what it might look like. 3.2 Weedon Street Model For this study, a model was created based on the plans for the redevelopment of a brown field site by the current owners, British Land. This model used simplified massing models for the proposed buildings, but detail was added to vegetated and river areas. This pilot study brought together the URSULA researchers in several informal master-planning workshops to develop alternative designs for the site incorporating URSULA research. The model of the site was made available during this process using a laptop and projector. Within this setting, the visualisation was used for reference purposes, where participants gauged the size and shape of the site as well as the relief of the terrain. Each redevelopment plan was captured using pencil and paper sketches over existing map data; these were subsequently digitised and turned into visualisations, some views of which are shown in Figure 3. Figure 3. Example screen shots of the Weedon Street model Both pilots were useful in developing a streamlined work-flow, and for learning the strengths and weaknesses of the approach, in particular they indicated which parts of the work-flow would prove difficult to achieve in real-time or even near real-time. 3.3 Work-flow analysis Table 3 shows a breakdown of time taken to produce the visualisation models. It should be noted that much experimentation with possible approaches was undertaken during the production of the visualisation models, until a streamlined work-flow was finalised upon. The times shown are estimates for reproducing the models using the streamlined workflow. Table 3 shows that the time to create a visualisation model, although not exorbitant, was far from being "interactive". Clearly the time of construction of each category needs to be improved upon in order to create an interactive solution.

7 Rapid Prototyping of Urban River Corridors Using 3D Interactive, Real-time Graphics 199 In terms of making changes to visualisation models, the difficulty varied. Firstly, a barrier existed in the way changes were captured within the workshop environment, (using a paper sketch); to overcome this, a way of introducing changes directly into the visualisation system will be necessary. When the feature being changed was derived directly from a vector-region, then the poly-line primitive could be edited and the feature would update automatically in real time - this was the best case scenario. Where there was no such link then the features being changed needed to be removed and the new models added, which was a much lengthier operation. Tab. 3 Analysis of the work-flow. Ball St Weedon St Base-line ½ hr ½ hr Buildings ½ hr per building (from photos) 1 hr per paper sketch design ~ 15 buildings Roads/paths 1 hr 1 hr Rivers 1 hr 1 hr Vegetation 1 hr 1 hr 4 Conclusions & Outlook The work-flow piloted did produce visualisations useful to the URSULA project in reasonable timescales; it also identified bottle necks, such as changing the course of the river, which precluded interactive changes. Both of the pilot studies created an excellent medium for discussion of interventions and for analysis during planning discussions. The vector-region approach proved useful for the four "feature addition" categories within the work-flow. Indeed, the existing tools which maintained a link between vector data and the features these vectors defined allowed interactive changes to be made. These findings are being used to inform the next stages of the research, which is to look at ways of automating the feature addition aspects of the work-flow by using procedural modelling approaches based on a vector-region with associated attributes approach similar to Smart Terrain (BUCHHOLZ ET AL. 2006). Features defined by vector regions will be procedurally generated automatically, with the work-flow already developed still available to edit the results and also to manually add special features. This approach will address a shortcoming which has become apparent with the current method of construction, in that the various elements in the models do not have relationships defined between themselves. It is proposed that this more structured way of building a visualisation model would mean that, as design changes are suggested, the model would adapt rapidly to deliver a visualisation. An URSULA sustainability framework is being developed that will contain various indicators to elucidate the effects of interventions on an area and combine these to give an understanding of the sustainability of any proposed changes. As Isaacs et al. (2008) demonstrated, it is possible to link sustainability measures to visualisations and URSULA will ultimately look at combining design changes, visualisations and sustainability assessment.

8 200 E. Morgan, L. Gill, E. Lange and D. Romano 5 Acknowledgements This paper is based on work undertaken within the URSULA project, funded by the UK Engineering and Physical Sciences Research Council (Grant number: EP/F007388/1). The authors are grateful for this support, and to all the organisers and participants of the SWSG workshop, especially Tom Wild. The views presented in the paper are those of the authors and cannot be taken as indicative in any way of the position of the funders or of colleagues and partners. Any remaining errors are similarly those of the authors alone. 6 References Al-Kodmany, K., Using visualization techniques for enhancing public participation in planning and design: process, implementation, and evaluation. Landscape and Urban Planning, 45(1), An, K., Implementation of Real-Time Landscape Visualisation for planning process. In: Buhmann, E., Paar P., Bishop, I. & Lange, E. (eds.): Trends in real-time landscape visualization and participation. Wichmann, Heidelberg, pp Bishop, I.D., Visualization for participation: the advantages of realtime. In: Buhmann, E., Paar P., Bishop, I. & Lange, E. (eds.): Trends in real-time landscape visualization and participation. Wichmann, Heidelberg, pp Buchholz, H. et al., Automated Construction of Urban Terrain Models. In: Riedl, A., Kainz, W., Elmes, Gregory A. (Eds.) Progress in Spatial Data Handling, 12th International Symposium on Spatial Data Handling, Springer, pp Deliverance Software, Simmetry 3d, version 3.1. Available at: [Accessed March 2, 2009]. Google, SketchUp, version 1.6. Available at: [Accessed January 2, 2009]. Herwig, A. & Paar, P., Game engines: tools for landscape visualization and planning. In: Buhmann, E., Nothelfer, U. & Pietsch, M. (eds.): Trends in GIS and Virtualization in Environmental Planning and Design. Wichmann, Heidelberg, pp Hoinkes, R. & E. Lange, D for free: Toolkit expands visual dimensions of GIS. GIS World., 8 (7), Isaacs, J., Falconer, R. & Blackwood, D., A Unique Approach to Visualising Sustainability in the Built Environment. In Visualisation, 2008 International Conference. pp. 3-10, 9-11 July Lange, E., Integration of computerized visual simulation and visual assessment in environmental planning. Landscape and Urban Planning, 30(1-2), Lange, E. & Hehl-Lange, S., Combining a participatory planning approach with a virtual landscape model for the siting of wind turbines. Journal of Environmental Planning and Management, 48(6), Lenné3D, Flora3D. Available at: [Accessed April 14, 2009]. Perrin, L., Beauvais, N. & Puppo, M., Procedural landscape modeling with geographic information: the IMAGIS approach. Landscape and Urban Planning, 54(1-4),