ITB J. ICT Vol. 3, No. 1, 2009, 1-18

1

The Investigation on Using Unity3D Game Engine in
Urban Design Study
1

Aswin Indraprastha & 2Michihiko Shinozaki

1

Graduate Student, Architecture and Urban Design Program
Department of Design and Engineering, Shibaura Institute of Technology
Shibaura 3-9-14 Minato-ku Tokyo 108-8548 Japan
Email aswinindra@gmail.com
2

Professor, Architecture and Urban Design Program,
Department of Design and Engineering, Shibaura Institute of Technology,
Shibaura 3-9-14 Minato-ku Tokyo 108-8548 Japan
Email sinozaki@shibaura-it.ac.jp
Abstract. Developing a virtual 3D environment by using game engine is a
strategy to incorporate various multimedia data into one platform. The
characteristic of game engine that is preinstalled with interactive and navigation
tools allows users to explore and engage with the game objects. However, most
CAD and GIS applications are not equipped with 3D tools and navigation
systems intended to the user experience. In particular, 3D game engines provide
standard 3D navigation tools as well as any programmable view to create
engaging navigation thorough the virtual environment. By using a game engine,
it is possible to create other interaction such as object manipulation, non playing
character (NPC) interaction with player and/or environment. We conductedanalysis on previous game engines and experiment on urban design project with
Unity3D game engine for visualization and interactivity. At the end, we present
the advantages and limitations using game technology as visual representation
tool for architecture and urban design studies.
Keywords: architecture; game engine; interactive virtual environment; urban design
study; visual representation.

1

Beyond Architectural Visualization

Architectural and urban design is always about idea of visualization andmaterialization. The importance of visualization is so crucial that twodimensional and three-dimensional graphics take the most part in design stages.
Throughout history, architectural drawings became major media for architects
to present ideas and visions to society. It is not surprising that information ofideas and visions are more important for the society (or, clients) than technicalor engineering drawing references. The term architectural visualization refers to
the media in which architects used to communicate the ideas to the clients.

Received April 21st, 2009.

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Aswin Indraprastha & Michihiko Shinozaki

The trend of architectural visualization comes up to the point that makes
depiction of real world as realistic as possible or even hyper-realistic. By theincreasing speed of computer processor and amount space in memory, this trend
also demands huge computer resources to render and to animate visualization
sequences. The basic role of architectural visualization is no longer for thecommunication purpose only but also for broader scope and functions such as
collaborative design process and marketing. At the same time, design processitself transformed into more parallel and multi-tasking activities. Design
visualization is needed not only as the culmination of design development but
as the input for design strategy as well.

2

Objectives

The objective of this study is to identify the advantages and limitations of using
game engine-based application for visual representation tool in urban design
study. By understanding its potentials and limitations, we are able to develop
new media for visual representation that integrates CAD applications with realtime interactive animation.

3

Related Researches

Game engine-based environment on a particular urban area could be atool to assist 3D visual simulation for policy maker and every stakeholder
in design study and process [1, 2]. Oxman noted [3] that as the basis forvisualization tool, game engines have basic advantage to save implementation
time by reusing its built-in functionalities such as rendering engines,
navigations and interaction tools. Modern game engines offer a high speed,
rendering quality, interactivity and multi-user support that are difficult to obtainusing any existing visualization tools.

3.1

Game Engine for Visualization Tool

The use of game engine has been developed under various natures of projects.
Commonly, the game world is built by importing its entire object fromparticular CAD/3D applications. In this case, a particular game engine thatusually comes with the game itself becomes a platform on which modification
or mod process is taking place. Modifying game level for architecture
visualization purpose is stimulating because it opens up the game engine for realtime data rendering and manipulation. Fairuz et.al [4] has studied that in thearea of visualization, game engines could quickly develop models and deploy itwith texture and lighting effect in game engine-based application with nofurther demand on high-end computer specification.

The Investigation on Using Unity3D Game Engine in Urban Design Study 3

In this study, we examined findings of three previous researches that madeattempt to use three different game engines as visualization tool. Despite a lotof technical specification on each engine, we focused on the findings of primaryfunction such as 3D geometry data input/output as well as lighting and texture
mapping. This consideration was taken mainly because those basic functions are
the most significant functions that take advantage from the 3D rendering andanimation software.
The summary of this study is depicted by Table 1.
Table 1

Summary of game engines for visualization.

EngineName
UnrealEngine 2

ReleaseYear
2003

Geometries I/OLighting

Built-in editor, any
CAD data must be
converted

Dynamic lighting
and shadow, HDR(High Dynamic
Range) Rendering
Dynamic lighting
and shadow, HDR(High Dynamic
Range) Rendering
Dynamic lighting
and shadow

Source-HalfLife 2

2004

No built-in editor,
any CAD data must
be converted

GamebryoOblivion

2006

CryEngine 2

2007

Built-in editor withlibraries, any CAD
data must be
converted
Natively read mostof CAD file format

Dynamic lighting
and shadow, Timeof day lighting

TextureMapping
3D vegetation
generator, shadermanagement
Optimization forlarge open area

3D vegetation
generator

Heightmap andpolygonreduction

Although all of these engines exhibit the capability of producing dynamic
visualization in less of production time than 3D rendering and animation
software, the main limitation of using these game engines as visualization tool
is laid on its flexibility [5, 6]. 3D geometries data must be converted when in
use in game engine. Therefore, there is no feedback or interactive mechanismwith 3D/CAD software, which architects used to produce design objects.

3.2

Game Engine for Interactivity Tool

In addition to visualization, virtual environment also has the potential to engage
users with interactive and communication systems. The virtual environment will
only be useful if it supports physically realistic behavior [7]. The types ofrealistic behaviors that are important depend on the specific application. In
architecture and urban design, usually we demand realistic representation of
spatial environment with naturalistic effect as well as dynamic elements that
inhabit it. Moreover, for interactive tool that could enhance spatial awarenessand comprehension to further make better design decision, it is important to4Aswin Indraprastha & Michihiko Shinozaki

consider how user can interact with game objects then how we can examine on
what interaction that has occurred.
We examined findings from two previous projects that use built-in interactivity
tool in game engines [8, 9]. Since interactivity is the element that is notprovided by any 3D rendering and animation software, it is important toconsider the ease of use of this function to enhance the quality of architecture
visualization. Table 2 provides the summary of previous findings.
Table 2Engine Name

Summary of game engines for interaction.
Interactivity function

HalfLife 2

Built-in interaction editor, limited only for non-playable objects. Basicnavigation provided.

Renderware

C++ script to build interaction with objects and users

Both findings resulted in the ease of use or learning curve. Scripting mechanismis the main issue to build interactivity using game engines. For the use inarchitectural or even urban design study, interaction system is based on theassumption that we can observe, examine as well as explore in three dimensions
in real-time whatever objects we want to interact with. This kind of demand
may require script programming in order to get high flexibility and freedom toachieve those goals.

4Constructing Virtual Urban Using Unity3D Game Engine

In our research, we use Unity3D game engine as the fourth generation of gameengine that combines visual simulation capabilities with interactive functions
and ease of use in the context of geometry data input and output. We pointed
out that architectural visualization done by computer has disadvantages asfollows:
a. Functional deficiency: it tends to separate the process of designing andthe process of visualizing. Even further, graphical projections nowadays
have no benefit with the design process. The visualizations are the final
products and have no functions as design tool as it was.
b. Resources deficiency: there is no limit in pursuing realism of computer
rendering or animation as long as there are enough resources. Thisdependency trend is ineffective and inefficient. Focus of design
solutions may have been overlooked by visual amenities.
c. Technical deficiency: CAD may already be left behind by othertechnologies in 3D applications. Game engines are uncultivatedThe Investigation on Using Unity3D Game Engine in Urban Design Study 5technology that offers more productive and effective aid for design
process.
By constructing virtual urban using Unity3D game engine we explored its
capabilities as well as its limitation with the focus on the design process.
The case study is a developed urban area at central district of Tokyo, Yaesu
district. This area is about 220 000 square meters and planned to become newdevelopment area. Yaesu area consists of mostly offices and commercial middle
rise buildings and many of them are registered as old buildings.
The development process of the virtual urban environment follows the sequence
shown in Figure 1. The 3D geometry data obtained from GIS application(ArcGIS) were prepared by private company [10] in the *.obj format to beinterpreted in Blender application.
GAME ACTIVITIES :exploration, explanation, engagement, educationGame interface :- walkthrough exploration-flythrough exploration-data bounding : GIS,
photographObtain Physical Existing Information
1. Site topography
2. Urban morphology :building size and shape ,street pattern,architecture, vegetation

GAME ENGINE
Virtual Simulation Stage I
Existing Condition

CAD

GIS

3D Geometry
Texture mapping

Attributes

Simulation I
spatial exploration,
explanation

Urban design study
and guideline

ANALYZE
compare with otherphysicalurban model(maquette)

Game interface :-variable manipulation- walkthrough exploration-flythrough exploration-data bounding : GIS,
photograph

Simulation II
user engagement

GAME ENGINE
Virtual Simulation Stage II
Various scenario
and design concept

Improved
Urban design study
and guideline

ANALYZE
alternative
design solution

SYNTHESIZE
alternative
design solution

DESIGN ACTIVITIES :analyzing variables (divergen) – synthesizing best option (convergen)

Figure 1 Framework in constructing virtual urban.

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Aswin Indraprastha & Michihiko Shinozaki

At the scale of urban, the complexity of polygon and texture mapping system
becomes the main consideration. GIS applications provide 3D polygon exporterbut not including any texture mapping system. In the case study, only building
has its 3D geometry data in ArcGIS. The orthographic photograph of eachbuilding facade is obtained from a mapping-service company. This researchuses poly reduction technique and using un-wrap technique for texture mappingin Blender3D software to solve the polygon complexity and mapping system
issues. Figure 2 shows the detailed process of overall 3D construction.
Text-based
data

GIS
Application

UNITY3D 2.0
Application
3D Polygon

Game World
mesh texture lightother animatedmedia elements

navigationmanneruser
interface

exploreinteract

BLENDER Application

ReducePolygontexturemapping

add static& animatedmodel

CompileGame

Run
Experience

Game Scenario

Image
EditorFigure 2 Overall process.

The method for constructing virtual environment for this research can bederived into the following stages:
1. Game world stage: including 3D data acquisition and development, otherstatic game objects as urban furniture such as vegetation, street lights andothers as well as animated game objects as urban elements such as vehicles,
humanoid characters.
2. Game scenario development stage, including navigation system andinteraction system.

4.1

Data Acquisition

Game world construction begins with 3D data acquisition. For such purpose,
this research use GIS-based 3D data from ARC GIS provided by Tokyo Digital
Map Corporation. Automatic 3D data acquisition is employed by using several
file format exporter provided by ArcGIS. Table 3 shows features of each fileformat and size of file it produced.

The Investigation on Using Unity3D Game Engine in Urban Design Study 7

Table 3File Format

File types and data size.
Properties and file size
file format : 3DS
filesize : 28 308KB
proprietary format of Autodesk (Autodesk 3DSMax, AutoCAD)
basically it store information about mesh (locationand dimension), material, camera and light

file format : DAE
filesize : 46 613KB
Digital Assest Exchange is from Collaborative
Design Activity for establishing an interchange fileformat for interactive 3D application.
Basically it is XML file and used in various 3D
application because it is not proprietary based.
store information about mesh, material and shader,
physics content

file format : FBX
filesize : 49 286KB
proprietary format of Autodesk (Maya)it store information about mesh, image maps, UV
mapping.

file format : OBJ
filesize : 11 465 KB
proprietary format of Autodesk
basically it store information about mesh andmaterial

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Aswin Indraprastha & Michihiko Shinozaki

From the table it can be concluded that the minimum file size is achieved byusing .obj file format. Since 3D data mostly consist of simple polygons that
represent buildings, the next step is to examine whether these polygons areconstructed by using minimum vertices.
Figure 3 shows three characteristics of 3D data opened in Blender: number ofobject, number of vertices and memory usage. Result shows that although 3D
data came from the same objects in ArcGIS, the number of objects varies.
Number of vertices and memory usage follow accordingly. This issue is due tothe file format specification.
OBJ
Num.of object
Num. of vertex (K)Memory usage

3DS
7421
79.8
83.66

DAE
14941
838
241.6522361
159161.12Filetype Comparison
22500
20000
17500
15000
OBJ
3DS
DAE

12500
10000
7500
5000
2500
0
Num.of object

Num. of vertex (K)Memory usage

Figure 3 File-types comparison.

The examination of each 3D polygon to reach minimum vertices usage is doneby using semi-automatic method in Blender called Poly-Reduction1. Basically,
it will count vertices of each selected object, reduce the number of polygonal
faces in particular mesh and scan if there is any vertex duplication. It is semiautomatic because it needs to do fix-up editing afterwards.
After applying Poly-Reduction method and performing some fix-up editing, it isclear that the number of vertices decreases. It also affects the file size and1Semi automatic method in Blender, based on Python script

The Investigation on Using Unity3D Game Engine in Urban Design Study 9

memory usage. Figure 4 shows the difference between scene before PolyReduction and after Poly-Reduction.

No Polygon Reduction-Num. of objects : 1018
-Memory usage : 54.14 MB

Polygon Reduction-Num. of objects : 318-Memory usage : 51.83 MB

Figure 4 Polygon reduction and data comparison.

4.2

Visualization Techniques

In order to achieve graphic performance as appropriate as the most 3D
rendering applications, we explored Unity3D capability to handle basic function
such as large scale texture mapping and dynamic lighting (see Figure 5). The
main factor taken into consideration is the balance between graphic
performance and real-time simulation.

3D Model in Blender, baked- lighting using ambience occlusion
technique to render texture map

Adjusting texture map
withorthographic photograph

Applying final texture in 3D mesh in
Unity3D

Figure 5 Procedure of texture mapping and baked-lighting.

For such condition, there are two constraints of texture mapping to obtaingreater performance both in graphics and game play (see Figures 6 & 7):

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Aswin Indraprastha & Michihiko Shinozaki

1. Texture size must be as small as possible and visually appropriate.
2. Texture must be layered with baked-lighting information to get lighting
effect (ambient occlusion) during game play.

-image size : original 1024 x
1024 pixel-memory consume : 652 KB-visual quality : high quality,
antialiasing, detailed relief-image size : 512 x 512 pixel-memory consume : 170.7 KB-visual quality : appropriatequality, nearly no-difference
from 1000 x 1000 pixel-image size : 256 x 256 pixel-memory consume : 42.7 KB-visual quality : poor and loose
detailFigure 6 Comparison of texture size.

The Investigation on Using Unity3D Game Engine in Urban Design Study 11

Texture Size and Memory Consumtion
700
650
600
550
500
450
400

Memory Usage (KB)
Total Memory Usage (MB)

350
300
250
200
150
100
50
0
1000 pixel

512 pixel

256 pixel

Figure 7 Memory size comparison.

As result, for further development in Unity3D we mainly use 2D texture in 512
x 512 pixel resolution.

4.3

Interaction Technique

Virtual reality in game-based environment consists of two parts: game world(game environment and all game objects) and game design (game scenario that
determines how the game will be played and how the game world wouldinteract with the user or with other game objects).
Our first intention on investigating Unity3D is to explore its ability as a tool for
design study, how it differs from any other available 3D applications or any 3D
viewer and presentation authoring applications and what is the advancement(see Table 4).
Therefore before we expand our investigation, we start with architecture design
point of view. We regard game engine as an engine to develop our tool
therefore it is important to consider aspects of design study to be incorporated inthis application and at the same time investigating the method and technique toaccommodate such requirements.

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Aswin Indraprastha & Michihiko Shinozaki

Table 4
Game DesignGame design and requirements.

Unity3D- based

Other applications

application
create 3D environment which
visual quality balance with thegame performancemaximum visual quality for less visual quality features (VRML,
real world representation, i.e Flash-based): light and shadow, alphachannel, texture map, timeframe independent animation

create system of navigation
which allow user to explore withmaximum degree of freedom

allow maximum degree of
freedom to explore andnavigate in virtualenvironment

pre-programmed animation sequence(3D animation), less flexible freedomof movement (QuickTime VR)view direction, high degree ofnavigation system (Bentley-3D PDF)

create system of navigation
which allow user to examine
particular object of interest in
various way of perspectives

method to enhance spatial
comprehension

view direction, high degree ofnavigation system (Bentley-3D PDF)

create method to incorporate
various type of informationrich content and other databounding techniquerequire script language and serverbased interaction (Flash-based)create method to accommodate
flexible 3D data exchange

method for 3D datainterchangeable to external
tool

less flexible to perform datasynchronization (Flash-based andother animation packages)

create a method to translate
conventional analysis study

method to perform somebasic visual-based analysis

less flexible

flexibility to expand game design Object-oriented programming

4.3.1

Navigation

The navigation system is the main important to be considered in thisapplication. As for a tool to examine 3D world, the main considerations ofdeveloping navigation system are:1. It must be easy to learn, easy to remember and easy to use with maximum
intuitive level as possible.
2. It must have rich features on minimum key input
As navigation system is crucial both for exploration and comprehension of 3D
environment, we then elaborate the design of navigation system into thefollowing criteria:
1. There are two main navigation systems: Human Eye View (HEV) (First
Person Camera) and Bird Eye View (BEV). Both are triggered by mousestroke on an icon.

The Investigation on Using Unity3D Game Engine in Urban Design Study 13

2. On each navigation method, instead of using icon-based navigation panel
for pan, zoom, orbit and others (see Figure 8), each method has contextual
button using mouse-keyboard stroke combination.
In BEV:- zoom: using mouse scroll wheel- orbit: using mouse movement- pan: using mouse left click – and drag-Figure 8 Pan, zoom and orbital navigation using mouse.

3. In FPS, we use standard view navigation for FPS game (see Figure 9) :- look and turn : using mouse movement- walk forward : using key “w”- walk backward : using key “s”- slide left : using key “a”- slide right : using key “d”

w
a

d
s

Figure 9 Turn/look and move toward direction using mouse and keyboard
combination.

All these navigation system are programmed using Unity3D JavaScript since itdoes not provide any built-in navigation system as available on previous webbased applications.

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Aswin Indraprastha & Michihiko Shinozaki

Snapshot

Function
HIDE/SHOW
Hide selected object and show selected object

ISOLATE/ SHOW ALL
Isolate : hide unselected objects in the samebuilding's lot

RETURN
Back everything to normal

Figure 10 Snapshot of interaction functions.

4.3.2

Interaction

Main considerations behind an interaction system are:
1. object manipulation: select, hide, show, isolate, swap
2. information retrieval : text, image, video
Object manipulation method is a feature that allows user to select any particular
objects and perform such task that has effect on those objects. It mainly focuses

The Investigation on Using Unity3D Game Engine in Urban Design Study 15

on the interaction in such a way that the user has the focus on this particular
object. The manipulation method provides hide/show selected object or
hide/show other objects, and isolates particular object from others (see Figure
10).
In the context of design study and urban design study in particular, virtualenvironment with this kind of interaction gives user flexibility to examine andto comprehend objects and its context. Combined with a navigation system, thisapplication can be used as a tool for conducting urban-scale visual
representation with advancement in flexibility to manipulate objects at realtime.
In addition, we develop another feature named: Swap Object. This feature allow
user to change selected mass or object with new mass from the preset gallery(see Figure 11). The main reason to put such a feature in is to allow user
examines the effect of design transformation on 3D objects and its surrounding
environment. This feature is not available in any previous applications.

Figure 11 Snapshot of swap objects.

Another function to push the ability of a game engine as tool for interactive
visualization is interactive animation. In this case we are about to show an
animation of building process within the game environment (see Table 5 andFigure 12). We promote a new way to represent architectural or urban design by
combining animation and interactivity in game environment.
In game engine-based environment, animation can be bound by using its object
and key frame information. Unity3D translates this information and wrap-up

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Aswin Indraprastha & Michihiko Shinozaki

animation at runtime. As a result, the animation can be viewed from any
viewpoint.
Table 5

Type of animation techniques.

Type of animation
representation

Conventional Animation

Propertystatic, user become spectator, no interactivity.

Interactive visualization using static, user engage with application using point-click methodauthoring softwareand others. 2D animation
Interactive visualization using dynamic, user engage with application in 3-dimensional
game engine
world

Building's lot selected, user can hide the buildings

Animation sequence on selected object

User can examine animation from any view point

Snapshot after animation completedFigure 12 Snapshots of interactive animation.

The Investigation on Using Unity3D Game Engine in Urban Design Study 17

5Conclusion

We found some findings on evaluation of Unity3D game engine as a tool for
design study by examining the aspects of visualization and interaction. By
considering these two factors, we emphasize on the data compatibility between
Unity3D game engine and CAD/GIS software (Blender, AutoCAD, ArcGIS).
This compatibility and interoperability of game engine has significant factor for
the integration of digital design tools.
From the experiment, we found significant improvement of CAD datacompatibility in Unity3D as it can natively read most CAD file types.
Furthermore, seamless integration between game engine and CAD applications
makes file synchronization possible. We experienced that .obj file format is themost effective format to be exported to Unity for meshes as .fbx to animation.
For the interaction mechanism we created scripts and develop basic interaction
system that engages users within this virtual environment. From one side ofview, Unity3D JavaScript-based language gives freedom to create interaction
system based on our own preference and ideas. Some of 3D navigation systems
that we created are learned from other applications such as Google Earth,
Adobe 3D PDF, Corona VRML player and others.
Object oriented programming language also gives an advantage in the way that
any interaction method came from game object behavior and it responds to userinteraction. The script-based interactions also open possibility to create aninteraction system that bounds external data into game object. For example, webound external data of text, image, and video into game interaction.
Although Unity3D has the potential to facilitate the development of an
application that can be a 3D viewer and 3D simulation with interaction featuresat the same time, it has some limitations regarding to its function as a general
purpose game engine application, which leads to some restraint conditions
particularly in non-computer science fields.
In architecture and urban design study, the limitation comes mostly by the factthat Unity3D has not been equipped with computer aided design tools that areusually embedded in such applications. As for visual representation tool with
object-based interaction system that mostly done by using Boolean algorithm,
Unity3D comes with appropriate features and capability in delivering such
simulation.

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