Workflow for Interactive High-end 3D Visualization … · 2010-01-09 · Workflow for Interactive...

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Workflow for Interactive High-end 3D Visualization in Site Planning Rüdiger MACH Introduction High-end visualization is fun, it looks good and is convincing. But more important for engineers, architects and planners is the fast, efficient, attractive and correct visualization of all kinds of design data during the planning process. Grand scale construction projects are very expensive. Insufficient coordination during the planning phase, planning mistakes and the “human factor” will produce additional costs, which are usually not taken into account beforehand. The early use of interactive 3D visualization can help to avoid some of these sources of errors. One needs tools which are able to combine all kinds of required data: landscape, terrain and design data have to be visualized – quickly and efficiently – globally and locally. Data import and navigation have to be as simple as possible. A very important detail is that specialists as well as non-specialists must be able to explore the data. This article shows the workflow of pre-visualization of planning data using the TerrainView Product Suite. 1 A Communication Platform? Conveying large planning schemes, which are geo-referenced, is the primary objective. Bringing together the plans in good time can help to support critical decisions and to communicate complex ideas quickly and efficiently. The mixture of data which is created in planning has to be preprocessed quickly and efficiently and has to serve as a basis for time-critical discussions. For this, one needs a communication platform, which enables the integration of diverse data without requiring specialist knowledge. Bringing design data together – at an early planning stage – may facilitate the decision-making process in complex projects. For big projects in the process of planning, the “right” communication platform can save expenses and trouble. 2 General Requirements There are considerable requirements, and the fields of implementation are very complex in as broad a subject as this. Diverse programs and methods at the start of a project or plan place extremely high demands on shared data interfaces and the possible integration of data.

Transcript of Workflow for Interactive High-end 3D Visualization … · 2010-01-09 · Workflow for Interactive...

Workflow for Interactive High-end 3D Visualization in Site Planning

Rüdiger MACH

Introduction

High-end visualization is fun, it looks good and is convincing. But more important for engineers, architects and planners is the fast, efficient, attractive and correct visualization of all kinds of design data during the planning process.

Grand scale construction projects are very expensive. Insufficient coordination during the planning phase, planning mistakes and the “human factor” will produce additional costs, which are usually not taken into account beforehand.

The early use of interactive 3D visualization can help to avoid some of these sources of errors.

One needs tools which are able to combine all kinds of required data: landscape, terrain and design data have to be visualized – quickly and efficiently – globally and locally. Data import and navigation have to be as simple as possible. A very important detail is that specialists as well as non-specialists must be able to explore the data.

This article shows the workflow of pre-visualization of planning data using the TerrainView Product Suite.

1 A Communication Platform?

Conveying large planning schemes, which are geo-referenced, is the primary objective. Bringing together the plans in good time can help to support critical decisions and to communicate complex ideas quickly and efficiently.

The mixture of data which is created in planning has to be preprocessed quickly and efficiently and has to serve as a basis for time-critical discussions. For this, one needs a communication platform, which enables the integration of diverse data without requiring specialist knowledge. Bringing design data together – at an early planning stage – may facilitate the decision-making process in complex projects. For big projects in the process of planning, the “right” communication platform can save expenses and trouble.

2 General Requirements

There are considerable requirements, and the fields of implementation are very complex in as broad a subject as this. Diverse programs and methods at the start of a project or plan place extremely high demands on shared data interfaces and the possible integration of data.

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CAD programs, such as AutoCAD, Microstation, Allplan and Vectorworks are used, as well as diverse add-on products, such as Civil3D (AutoCAD) or Inrail (Microstation).

Many a planner chooses GIS tools like Esri’s ArcGIS or Manifold from the start. These programs produce data formats which can seldom be represented without problems in Real Time visualization environments.

Such basic data usually consists of:

1. GIS data • Imagery, • Elevation, • Vector and • Annotations

2. Planning data to integrate 3d models like: • Buildings, • Technical detailed constructions and • „Local” elevation models (reduced to a small area).

The quality of visualization can vary considerably and it is hard to find the tool which meets one’s needs precisely. It depends on the objectives of the project. Some general demands on Real Time visualization might be described as follows:

1. Representation of unchanged geometry – There must be no polygon reduction; if this is unavoidable, it has to remain controllable.

2. Integration of „large“ textures – These are aerial pictures or other textures compressed without loss.

3. LOD - Level of Detail – Elements beyond a defined distance from the camera are simplified.

4. Velocity – Fast and easy navigation within the VE (Virtual Environment). 5. Actions/Behavior – The option to include links and special behavior like collision or

intersection detection. 6. Operation/Navigation – Easy use of navigation elements. 7. Platform/Presentation – Platform independence. 8. Data transfer – Data interface for the most commonly used programs.

These points refer to the requirements of viewing large-scale data, and to the interaction with this data in an IE (Interactive Environment).

3 Trends and Problems

There is a trend towards using special interactive 3 dimensional applications (BUHMANN, PAAR, BISHOP & LANGE 2005). It makes sense for users to be able to navigate on their own, be it when using a communication platform for specialists or simply a medium for presentation. Interaction encourages learning, as the user is able to experience an environment at a speed and in a way that suits himself; it reduces the user’s inhibitions to use certain software, and enables further discussions between colleagues (SHNEIDERMANN, MACKINLAY & CARD 1999).

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In this context, special attention can be placed on so-called Virtual Globe applications. The complex and interesting fields of application of virtual globes are: • Planning/engineering/architecture • Cartography and navigation • Research and development • Petroleum, electricity and gas industries • Tourism • Insurance • Television/broadcast • Crisis and catastrophe management

Three aspects hinder the quick and efficient use of visualization tools in the field of planning. Two of these aspects are – when using geo-referenced data – the “right” reference system, and the definition of the units used in planning. Here, still, it is necessary to communicate clearly which co-ordinate or projection system is to be used, and of course, which units are in use or whether one is working in meters, centimeters or millimeters.

4 Virtual Globe?

While the idea was already presented in 1992 by Neal Stephenson1 in his novel “Snow Crash”, the “real” concept of “virtual globe” is relatively new, and is only now starting to become established in the minds of users and specialists. Already in mid-2003, supplementary to its GIS application ArcGIS2 , ESRI brought out the application ArcGlobe. TerrainView-Globe3 which is specialized for commercial professional solutions, was released in 2004. Leica4 developed the Virtual Explorer, Microsoft is concentrating on MSN Virtual Earth5 , Skyline is selling Skyline Globe6 , NASA has made its product WorldWind7 freely available, and probably the most well known version of a virtual earth is Google Earth8.

A virtual globe application is a program or system which is able to represent diverse forms of 3D, elevation, imagery and vector data interactively in a “global” context. Usually, a global co-ordinate or projection system is used, such as WGS849 . If arbitrary planets are to be represented, one refers to them as virtual globes, whereas a representation of the earth is called a “virtual earth”.

This spontaneously makes one think of the term GIS, or Geographic Information System. A GIS is certainly the right tool to use in order to utilize and analyze such large amounts of data. It is, however, not able to show 3 dimensional data in real time. Large data banks and 1 http://www.nealstephenson.com/ . 2 http://www.esri.com . 3 http://www.viewtec.ch/ . 4 http://gi.leica-geosystems.com/ . 5 http://local.live.com/ . 6 http://skylineglobe.com . 7 http://worldwind.arc.nasa.gov/ . 8 http://earth.google.com/ . 9 http://www.wgs84.com/ .

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virtual reality applications are not very compatible. However, a virtual globe application enables the user to move through the scene as if it were a scene from a computer game. A detailed description of virtual globes can be found on http://en.wikipedia.org/wiki/ Virtual_globe.

Compared to the requirements for “pure” real time environments, following points remain for the use of virtual globes: • 3D Geo content – the system must be able to process and represent well-established

earth data and supplementary geo information such as elevation data, imagery, vector declinations / surfaces and annotations.

• 3D models – supplementary 3D models are an important aspect when creating convincing visualizations. Examples of these are buildings, landmarks, city models, vegetation etc.

• Navigation – the navigation should be simple and intuitive, and options such as “walkthrough”, “flythrough” or “target search” are desirable.

• Navigation additions – creating POIs (Points Of Interest) and flight paths helps the user to find additional and describing information

• Streaming – the Internet enables the quick and distributed access to large amounts of data. Therefore, the data should be able to be optimized for streaming.

• Integration – the importing of arbitrary data streams (e.g. GPS data or movement data) which can be interfaced with a virtual globe with 3D models or arbitrary information.

5 TerrainView-GlobeTM TerrainView-Globe is a part of the TerrainView product suite of the Swiss company Viewtec AG, and it is the advanced version of the product TerrainView, which was originally developed as a VR viewer and editor. Detailed information can be found at www.viewtec.ch.

6 Constituent Parts and Practical Use TerrainView-Globe has a special mixture of dealing with the previously mentioned diverse kinds of 3D data from GIS and planning. GIS data can be used for global or very large sets of data, and arbitrary 3 dimensional planning data can be “mixed” into these environments as well (MACH 2007).The great advantage of this application is that diverse data can be brought together and can be visualized at the start of a project without too much effort. This provides a communication platform, which enables one to view complex plans quickly and easily, and to check for flaws or weak spots.

7 Workflow The workflow of TerrainView-Globe is simple and uncomplicated. A mixture of data, consisting of 3D data for models, geo content and descriptive information can be optimized and edited for the streaming rendition.

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The program supports 2 500 co-ordinate and projection systems, current height, image and vector formats, as well as the most commonly used 3D formats. This guarantees that just about any geo-referenced data set has a place on the global platform.

If the data is not geo-referenced, data can also be freely positioned and shifted about. Additional 3D objects, height, image and vector data can be downloaded or imported.

All data can be switched on or off in a special layer technique, or be blended into each other.

8 Geo Data

The following Figure 1 shows the data set which serves as the basis for the earth, which is based on „World SRTM 90 m10 “ for the elevation data, as well as „NASA Blue Marble Next Generation11 ” with a resolution of 500m per pixel.

Fig. 1: Screenshot TerrainView-Globe

10 http://www2.jpl.nasa.gov/srtm/ . 11 http://earthobservatory.nasa.gov/Newsroom/BlueMarble/ .

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When geo-data is imported, it not only gets downloaded into a scene, it is also optimized for use in a virtual reality environment. This means that it is adapted and tiled with special LOD12 -Algorithms in such a way that a web stream with a repeat rate of up to 60 fps13 is possible.

This kind of conversion is applied to elevation data, imagery, vector data and additional information. The processing of this data solely takes place in the integrated pre-processor. However, the importing of data does take a little longer, as the data has to be re-projected from the co-ordinate system at hand to WGS84. Ideally, the data is already in the appropriate system to start with. Figure 2 shows the geo data set which has been imported additionally to the earth data set.

Fig. 2: Screen shot with an example of an imported geo data set consisting of an elevation model and the corresponding aerial photograph. The background shows Switzerland with an aerial photograph and a topographical map. (© Swisstopo14 , 25 m DEM) The two maps can be blended into one another like layers in Photoshop.

12 LOD – Level of Detail. 13 fps – Frames per Second. 14 http://www.swisstopo.ch .

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9 Terrain Model as an Object in 3D

Any arbitrary digital terrain model which is available in one of the commonly used 3D formats is opened via the file menu. Formats which are supported are listed in the appendix. In this case, the terrain is treated like a 3 dimensional object (Fig. 3), and can be switched on or off as necessary.

Fig. 3: Screen shot with an example of an imported geo data set. (© Swisstopo) Additionally, this data set was prepared in 3ds Max and downloaded as a 3D object via the ViewTec IVC plug-in.

10 3D Object

In any 3D application (CAD, visualization) such as AutoCad, Civil 3D, Allplan, 3ds max, Cinema4D or Softimage, a 3 dimensional subject matter is created and edited. Depending on the effort required, this 3 dimensional subject matter can be optimized especially for the needs of 3D interactive applications.

An appropriate optimization, for instance “Texture Baking” with light and shadow information, varies depending on the application, and the description of this will not be

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Fig. 4: The figure shows a pre-planning state of power lines. The digital elevation

model is based on an ArcGIS ASCII grid, the power lines have been build in AutoCAD (© Swisstopo15 , 25 m DEM, © Atel Schweiz16).

discussed in further detail here. Figure 4 shows a screenshot of a project, where the location of power lines had to be discussed.

11 Data Formats supported in TerrainView-Globe

Digital Elevation Models • Arc/Info ASCII • Arc/Info Binary (.adf) • USGS SDTS DEM (*CATD.DDF) • TIFF/GeoTIFF (.tif) • Military elevation data (.dt0, .dt1) • USGS ASCII DEM (.dem) • Atlantis MFF • VTP Binary Terrain Format (.bt) Image Formats • ERMapper Compressed Wavelets (.ecw) • TIFF/GeoTIFF (.tif)

15 http://www.swisstopo.ch . 16 http://www.atel.eu/de/group/ .

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• Erdas Imagine (.img) • JPEG2000 (.jp2, .j2k) • JPEG JFIF (.jpg) • Multiresolution Seamless Image Database (MrSID) Vector Formats and Annotations • Arc/Info Binary Coverage • ESRI Shapefile • Mapinfo File • Microstation DGN • U.S. Census TIGER/Line 3D Formats • ViewTec IVC • Multigen OpenFlight • OpenScenegraph IVE, OSG • Carbon Graphics GEO • CyberCity FLT, IVC • Autodesk 3DStudio 3DS • Autodesk 3D Studio Max (for versions 6,7,8 ViewTec Plug-In which is free of charge

is necessary) • VRML 2 WRL • Design Workshop DW • Alias/Wavefront OBJ • NewTek LightWave 3D LWO

Controls and Navigation The surface is intuitive and easy to use. The view mode is active by default. This enables a free navigation through and over complex 3D environments. Further navigation modes such as Flight Mode, Explore Mode or Low-Level Mode make advanced maneuverability within the scenes possible.

Extra Features Some extras, which are interesting for visualizers, are the creation of POIs (Points of Interest), flight paths, the possibility of crating an unlimited amount of screen shots, the output of HDTV film material, and a convincing weather engine, 3D objects can be switched on or off. Studies in variation are therefore simple to operate and execute.

12 Summary and Conclusion

Data volumes are increasing, and in fields like catastrophe management, large construction projects and planning, new tools are necessary to be able to view and present this data at early planning stages. The classical 3D animation is too time consuming and the games industry and new media have increased the demands of viewers and changed their viewing habits.

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TerrainView-Globe fills a niche in the field of highly complex virtual reality applications for technically demanding issues. Security-sensitive and complex data can be processed and visualized using this platform exceedingly quickly.

Simple to handle and quickly fed with the required data, this is a tool which more than fulfils the needs caused by today’s data volumes.

References

Buhmann, E., Paar, P., Bishop, I. D. & Lange, E. (Eds.) (2005), Trends in Real-Time Visualization and Partizipation. Proceedings at Anhalt University of Applied Sciences 2005. – Wichmann, – Wichmann, Heidelberg.

Mach, R. (2007), Virtual Globes. – In: Digital Production, 1/2007 Shneidermann, B., Mackinlay, J. & Card, S. (1999), Readings in Information Visualization

(1st edition). – Morgan Kaufmann Publishers.

Software

http://www.viewtec.ch – Homepage of TerrainView