Visualizing Boathouses of Dwejra Bay in Gozo, Malta for Access Through WebGIS Applications

Erich BUHMANN, Matthias PIETSCH, Daniel LANGENHAUN, Santosh CHOUGULE and Philip PAAR

Keywords

Digital Landscape Architecture, 3D-Scanning, DTM, Planting Visualization, ArcGIS, Google Sketch Up, Lenne3D, webGIS, ESRI ArcGlobe™, Medisolae-3D, Google Earth™, MS Virtual Earth™

Abstract

This study is being undertaken to support an appropriate tourism design and management of “Dwejra Coastal Nature Park”, one of the important tourist points in Malta. The main design idea is to enhance the facilities of the most popular tourist area of Gozo Island, taking into consideration its natural scenic beauty, in order to promote the concept of Eco Island Gozo. The area was a very close candidate for becoming a World Heritage Site, and was nominated for EU Natura 2000. Based on laser scanning data, the entire workflow for creating 3D city models for visualization tasks in a Geobrowsers is to be explained and discussed.

1 Introduction

Realistic 3D presentations are essential in planning and architecture. A lot of Geographic Information systems provide these functions today. The capacity to produce 3D landscape visualizations has been transformed by a combination of developments in computer performance, software integration and data availability (APPLETON ET AL. 2002, PAAR

2006).

Since Google Earth, MS Virtual Earth and other Geobrowsers have been developed, digital globes have become a popular tool for displaying spatial data using terrain models (PIETSCH & BUHMANN 2006).

On the other hand the increasing development in Web-based GIS applications in the last years allows designing dynamic geoportals using different system architectures. Standardization like CityGML for city models (KOLBE 2008, GRÖGER ET AL. 2007) and Directives like INSPIRE create a great degree of standardization and harmonization. The MedIsolae-3D-Project is a state-of-the art WebGIS technology project which created a spatial data infrastructure (SDI) based on INSPIRE that implements a 3D aerial flying-over application for island-navigation as a virtual visiting tool linked to several geobrowsers including a geoportal for island information and sales of services. This has been developed for 100+ European Mediterranean Islands (BONAZOUNTAS ET AL. 2009). In the context of

Visualizing Boathouses of Dwejra Bay in Gozo, Malta for WebGIS Applications 407

Fig. 1: Location ofDwejra area(Source: OpenStreetMap)

this project, the study intends to describe a prototype for the entire workflow for modeling city models using different software products to use the results in different software environments or WebGIS architectures.

2 Study Area

The study area is situated at the western coast of Gozo Island in Malta (see Fig. 1). Dwejra Bay has a nearly vertical rim around an inland sea and has a number of small individual buildings. A tunnel con-nects the inland sea with the Medi-terranean Sea (see Fig. 2) and is one of the tourist attractions of this site and a real task for real 3D modeling.

Fig. 2: Current situation at Dwejra Bay (Source: BUHMANN 2008)

E. Buhmann, M. Pietsch, D. Langenhaun, C. Santosh and P. Paar 408

3 Data Sets

3D scatter plots from laser scanning (resolution for buildings 5×5 cm; resolution for surface 10×10 cm; resolution of the rim 20×20 cm) have been taken and processed by PAASCHE & PETZSCH (2004) without a reference system in dxf-Format. An aerial photo with a resolution of 25×25cm in the Reference System Stripped UTM – ED 1950 from 2004 could be used for texturing the surface. For texturing the buildings, photos of each building were taken by BUHMANN (2008) and LANGENHAUN (2009). The 3D Plant models had been taken from Lenné3D.

4 Methodology

The workflow diagram (Fig. 3) shows the actual working process for creating the 3D city models, step by step, to be used in Geobrowsers or for creating animations and flythroughs. For the GIS processes and the 3D modeling, the software versions Arc GIS 9.2 with 3D-Analyst extension and Sketch up 6 are used.

To import and export the results between the used software products, the following free plug-ins were used:

SketchUp plug-in for ArcGIS 9.2 Google plug-in for SketchUp.

Fig. 3: Workflow from laser scanning to 3D modelling and visualization to WebGIS-Explorer

Visualizing Boathouses of Dwejra Bay in Gozo, Malta for WebGIS Applications 409

4.1 Data preparation

Based on the high resolution of the 3D scatter plot (see Fig 4), and for the different modeling purposes, the terrain model and the building model were separated. Because of the limitation that actual elevation models in GIS software packages can only be modeled as 2.5D-models (each x and y coordinate has exactly one z coordinate) (BLASCHKE &

TIEDE 2005) the tunnel was extracted to model the rim without the tunnel. For calculating the digital elevation model, the surface was smoothed by generalization. Because of the different reference systems, all datasets had to be referenced to the base system Stripped UTM.

4.2 Workflow

For modeling the surface, a Triangulated Irregular Network (TIN) was calculated based on the laser scan datasets using the 3D-Analyst extension. The model was then converted into a raster digital elevation model (DEM) to generalize and smooth the very detailed DEM that originally had numerous artifacts. For the visualization of the Sketch up building model, individual facade pictures of all the buildings were taken. The photographs had to be matched to the different facades of the buildings.

Fig. 4: City model of Dwejra Bay based on the 3D scatter plots

E. Buhmann, M. Pietsch, D. Langenhaun, C. Santosh and P. Paar 410

Fig. 5: Building with textures

Fig. 6: Model of chapel exterior

Three different levels of detail were used for the overview, the buildings (Fig. 5 and 6) and the inside of the building (Fig. 7).

Visualizing Boathouses of Dwejra Bay in Gozo, Malta for WebGIS Applications 411

Fig. 7: Model of chapel interior

Fig. 8: Model in Google Earth

E. Buhmann, M. Pietsch, D. Langenhaun, C. Santosh and P. Paar 412

Fig. 9: Lenné3D Biosphere3D – Landscape Scenery Globe, beta (Biosphere3D.org)

Because of the missing reference system, all datasets have to be referenced to the base system. Therefore the textured 3D building model and the aerial photo were matched in SketchUp and exported to ESRI geodatabase while using an available plug-in such as ESRI Multipatch. The DEM and the geo-referenced aerial photo was imported to the same geodatabase. In the next step, all datasets were incorporated in ArcScene for creating different presentations and flythroughs.

In order to generate realisitic vegetation, Lenné3D vegetation models could be used to add photorealisitic 3D Objects. After adding all the elements, a city model of the whole area was created as a base model for different geobrowsers (Fig. 8 and 9).

5 Discussion

To create photorealistic visualizations, the entire process should work accurately. In the described study area, modeling the tunnel was impossible with the geodatabase used,. To solve the problem the rim was modeled ignoring the tunnel (see Fig. 9). For comparable situations, real 3D modeling should be implemented in existing GIS software packages in the future (TIEDE & BLASCHKE 2005).

Visualizing Boathouses of Dwejra Bay in Gozo, Malta for WebGIS Applications 413

Fig. 10: Model in ArcScreen with artifacts from the tunnel

For the data exchange between the different software products in this study, some plug-ins had been used. Sometimes, depending on the complexity of the 3D models, some problems occur when transferring all the information. Some of the plug-ins used won’t be enhanced in the future. Therefore, for future projects standards such as CityGML, Collada or others should be used for interoperable data exchange.

In the study area, 3D scatter plots were used for 3D modeling for the buildings and the surface. Normally 3D buildings are extracted by footprints of georeferenced orthophotos and extruded by the height of the buildings (BONAZOUNTAS, 2009). So the difference between the resolution of the 3D datasets and the visualization purpose should be defined at the beginning of the project. Smoothing and generalization might generate some problems by losing necessary information (e.g. walls).

6 Conclusions

The technical emphasis of this paper is to show the entire workflow from the initial laser scan to the virtual model in the web, using today’s standard software products. The study shows that the various software products can be combined. However the integration of models from product to product is suffering from the different update versions that usually do not consider the updates of the plug-ins. In order to use this process in a normal GIS planning environment, means of automatic processes have to be found. A computer generated, realistic 3D model of terrain and vegetation allows community members, developers and stakeholders to get a feel for the landscape with which they are familiar and see what a land claim would look like on the ground.

E. Buhmann, M. Pietsch, D. Langenhaun, C. Santosh and P. Paar 414

Visual representations of the real world are essential for landscape architects to express and communicate their thoughts.The landscape architectural emphasis is to use the power of the web in order to promote more sensitive landscape managing.

References

Appleton, K., Lovett, A., Sünnenberg, G., Dockerty, T. (2002): Rural landscape visualisa-tion from GIS databases: a comparison of approaches, options and problems. Com-puters, Environment and Urban Systems, 26, 141-162.

Bonazountas, M., Schaller, J., Martirano, G., Mattos, C., Roumeliotiss, L. & D. Kalli-dromitou (2009): “MedIsolae-3D”: Mediterranean Islands SDI and 3D Aerial Web-Navigation. In Buhmann et al. (Eds.): Digital Landscape Architecture 2009, Proc. of Presented Papers. Anhalt Univ. of Applied Sciences, Bernburg, Germany, May 2009.

Buhmann, E. & M. Pietsch (2008): Interactive Visualization of the Impact of Flooding and of Flooding Measures for the Selke River, Harz. In: Buhmann, E., Pietsch, M. & M. Heins (Eds.): Digital Design in Landscape Architecture. Heidelberg: Wichmann.

Buhmann, E. & M. Pietsch (2006): Von ActiveX bis XML: Neue GIS-Begriffe für die Kommune. Stadt und Raum, 5/2006, 236-241.

Ervin, S. & H. Hasbrouck (2001): Landscape Modeling: Digital Techniques for Landscape Visualization. McGraw-Hill.

Kwartler, M. (2005): Visualization in Support of Public Participation. In: Bishop, I. D. & E. Lange (Eds.): Visualization for Landscape and Environmental Planning: technology and applications. Oxford, Taylor & Francis, 251-260.

Langenhaun, D.: Touistische Anwendungsmöglichkeiten von GIS-gestützten Stadt- und Landschaftsmodellen auf der Grundlage von Laserscanner-Daten am Beispiel von Dwejra Bay, Gozo (Malta). Bachelorarbeit an der Hochschule Anhalt (FH) im Studien-gang Landschaftsarchitektur und Umweltplanung, Bernburg November 2009.

Langenhaun, D., Buhmann, E., Pietsch, M., Chougule S. & P. Paar (2009): Virtualizing Boathouses in Dwejra, Malta for Access through WebGIS Applications (Abstract) In Buhmann, E., Pietsch, M. & M. Heins (Eds.): Digital Landscape Architecture 2009, Proceedings of Presented Papers, 21 - 23 May, 2009 – Malta, Anhalt University of Applied Sciences / Hochschule Anhalt (FH), Bernburg, Germany, 86-92.

OpenStreetMap: Maltesische Inseln. http://www.openstreetmap.org/?lat=35.939&lon=14.426&zoom=11&layers=B000FTF. Version: 2009 { 09.11.2009}.

Paar, P. (2006): Landscape Visualizations: Applications and Requirements of 3D Visuali-zation Software for Environmental Planning. Computers, Environment and Urban Systems, 30, 815-839.

Paasche, D. & T. Petzsch (2004): Einsatz des Laserscanners HDS 3000 zur Visualisierung der Dwejra Bay auf Gozo. Thesis in surveying at Anhalt University of Applied Sciences, Dessau, Germany.

Peng, Z.-R. & D. D. Nebert (1997): An Internet-Based GIS Data Access System. Journal of Urban and Regional Information Systems, Spring 1997, 9, 20-31.

Tiede, D. & T. Blaschke (2006): Visualisierung und Analyse in 2,5D- und 3D-GIS – von loser Kopplung zu voller Integration? – Beispiele anhand kommerzieller Produkte. In Coors & Zipf (Hrsg.): 3D-Geoinformationssysteme. Heidelberg: Wichmann, 280-292.