Application of 3D Terrain Representation Systemfor Highway Landscape Design
Koji Makanae
Miyagi University, JapanNashwan Dawood
Teesside University, UKAbstract
In recent years, mixed or/and augmented reality, which aims to integrate virtual space with real space,
has received considerable attention. In particular, the development of a tangible interface is aninteresting research area. In this study, the objective is to develop and evaluate a tangible terrain
representation system (TTRS). The TTRS can be used to represent a terrain surface on a stretchable
screen by controlling its shape using 64 actuators (8 × 8) and projecting an aerial photograph onto thescreen. The TTRS can be used to determine a highway alignment by defining control points using amagnetic positioning device. When a highway planner sets the control point of a highway alignmenton the TTRS, the image of the highway alignment is projected onto the TTRS. A group of nine finalyear graduate students was selected to evaluate the TTRS against a virtual reality (VR)-based visual
3D representation. A well-defined evaluation measure of usability was developed and used. Further,the paper introduces a highway and landscape design system developed by using a desktop TTRS
system.
Keywords: virtual reality, tangible display, highway design and construction, landscape design,
digital terrain model, evaluation of usability

1Introduction

The current methods of highway alignment planning and construction include the use of 2D
topographic maps and the planners’ creativity and experience of interpreting images and otherinformation. A highway planner has to mentally reconstruct a 3D topographic image from 2D maps
using his/her experiences and intuition. Therefore, the accuracy of such images depends on theplanner’s ability and experience. Recent advances in the development and dissemination of spatial
information have made it possible to obtain and use various types of spatial information easily. It isalso becoming possible to obtain and use topographic information in many cases; this information canbe obtained in the form of mesh data such as USGS digital elevation models (DEM). Suchinformation can be projected two-dimensionally on a computer display to provide a bird’s eye view ofthe terrain; however, this representation method makes it difficult to intuitively understand thetopographic information.
To solve this problem, Makanae et al. (2005) have developed methods for representing virtual
terrain surfaces defined on a computer by applying virtual reality (VR) technology. These methods
can be used to realize highway design systems such as the highway route planning system using
stereoscopic visualization of aerial photographs and VR-CAD system for landscape design using ahead-mounted display. However, these systems have some problems. For example, the planner mustwear special stereoscopic visualization devices, and the alignment of the new route is not accurate. In
recent years, research and development efforts have been focused on mixed reality, which aims tointegrate virtual space and real space. One of these efforts is the research and development of atangible interface. Believing that a tangible interface will help solve the above-mentioned problems,
the authors have been working on the construction of a tangible terrain representation system (TTRS)
for highway design.
In the previous study, an evaluation of the TTRS was carried out. This evaluation clarified that theTTRS is an effective tool in terrain recognition. This paper introduces the mechanism of the TTRS, its
application to highway design, and the construction of an improved version of the TTRS forlandscape design.

2VR-Based Visual 3D Representation Method

Virtual reality (VR) is a technology that enables a person to experience a realistic virtual world
defined on the computer. The technology uses an interface that makes an effective use of stereoscopic
visualization. This is made possible by the use of two human eyes in order to visually enhance thedegree of reality.
The mechanism by which a human visually recognizes the 3D configuration of an object involves
two types of factors: physiological factors and psychological factors. Physiological factors, which are
due to the functions of the human eye, include the focus adjustment function of the lens, eyeconvergence, binocular parallax, and monocular motion parallax. Psychological factors, which help
reconstruct 3D images from experience, are classified either as geometric or as optical factors. Among
all these physiological and psychological factors, binocular parallax, which is a physiological factor,
is generally thought to be most important in 3D perception.
The stereoscopic visualization technology used in the field of virtual reality is based mainly on 3D
perception caused by binocular parallax. If the locations of the eyes of a human viewer are determinedin a virtual space defined on the computer, a pair of perspective images just like images that would beperceived by the two human eyes can be obtained by applying the computer graphics (CG)technology. By giving the perspective images thus obtained to the two eyes of a human viewer, theviewer can be made to perceive the images as a 3D object. Devices for providing different images tothe left and right human eyes have been developed during the evolution of virtual reality technology.
Representative examples of such devices are stereoscopic eyeglasses with liquid crystal shutters, 3D
displays, head-mounted displays (HMD), and immersive displays such as CAVE (e.g., Cruz-Neira,1993).
In recent years, research efforts associated with mixed reality, which aims to integrate virtual
space and real space, have also been developed. One of these efforts is the research and developmentof a tangible interface. The MIT Media Laboratory, for example, has developed a system called“Illuminated Clay,” which projects information onto a terrain surface created with clay (Piper et al.,2002).

3Construction of TTRS

We have been working to develop terrain representation methods making use of VR technology andto construct design support systems using these methods (Makanae, 2002, 2003). From theseresearches, we have identified the following problems of terrain representation and design support
system:-Difficulty in comprehending the relative positions of the terrain surface and the object of interest-Need for a special stereoscopic visualization device-Limited field of view-Not usable for group work
Some of these problems can be solved by using large-scale display systems such as a CAVE system.
They have no field of view limitation and can support more intuitive positioning and group working.
However, these systems require the users to wear a stereoscopic device and are thus expensive.
Believing that the introduction of a tangible interface will help to solve these problems, we have beenworking on the construction of a tangible terrain representation system (Makanae and Nakahara,
2005; Makanae and Nashwan, 2009).
Figure 1 shows the configuration of the terrain representation system. As shown, the systemrepresents a terrain surface by controlling the shape of a stretchable screen used for representing theterrain surface by means of 64 actuators (8 × 8) and projecting an aerial photograph onto the screen.
The size of the screen is 60 cm × 60 cm, and the moving range of each actuator is approximately 250
mm. In the TTRS system, the magnetic tracking system POLHEMUS FASTRAK is used as apointing device. As the planner sets the control point on the TTRS, the parametric alignment can becalculated automatically, and then it is overlaid on the aerial photograph and projected on the TTRS.
By using this system, the planner can obtain images of the terrain and highways intuitively withoutwearing any equipment. Each participant runs the design scenarios on the TTRS first and then on thestereoscopic viewer or vice versa.
Projector
Mirror

3D Magnetic
Position Sensor

RS232C

128 bit
Digital I/O
Board
Personal
Computer

128 bit
Digital I/O
Board

Pen device

Stretchable
ScreenControl
Unit

TTRS

Figure 1: Configuration of terrain representation system

4Usability Measures

The mesh data of Digital National Land Information (Japan) are used as terrain data, and the height ofeach actuator is determined according to the mesh data values. The scale of the terrain depends on theresolution and the grid interval. When the grid interval is 50 m, the system can represent a horizontal
area of 350 m × 350 m with a height of 209 m. When the grid interval is 1 km, the system canrepresent a horizontal area of 7000 m × 7000 m and a height of 4172 m. The resolution of this system
is limited to 8 × 8; however, the effective resolution for each purpose of terrain representation must be
considered in future.

In order to evaluate the usability of the TTRS, an experience is achieved. The scenarios arecomposed of series of tasks to develop a highway alignment using the TTRS and “3D stereoscopic”
tools. Topographic information of a location in Japan has been obtained in the form of mesh data suchas USGS digital elevation models (DEM). Aerial photograph images are taken into the computer inthe form of digital information and used in the stereoscopic viewer and TTRS. The tasks are torecognise the terrain and draw the 3D highway alignment in the 3D virtual space by setting some
control points for a parametric curve. By using the TTRS, the planner can obtain images of the terrain
and highways intuitively without wearing any equipment. Each participant runs the design scenarios
on the TTRS first and then on the stereoscopic viewer or vice versa.
Nine final-year students from Project Design at Miyagi University participated in the evaluation
process. Each student followed the scenarios identified above and developed a route for a highway
design using the TTRS first and then the stereoscopic system or vice versa. Each experiment lasted
about 1 h. Five students experimented with the HMD stereoscopic view first and then moved to theTTRS, and the other four experimented with the TTRS first and then moved to the HMD stereoscopicview.
The results of the questionnaire are given in Table 1. Respondents were asked to allocate a score
to each measure after completing the tasks that were assigned to them. Table 1 shows the score foreach respondent for 13 measures. The average and standard deviation were calculated so that theresults of HMD and TTRS could be compared. As a result, the tangible display produced better scoresthan HMD for all parameters except for “satisfaction with the ease-of-use” and “fun.” The TTRS
scored very high on parameters such as “easy to manipulate,” “easy to understand the features of theterrain,” “realism,” “learnability,” and “easy to understand the 3D position of the pointer.” These arevery important parameters that validate the use and deployment of the TTRS. On the other hand, theTTRS scored low on three parameters, “accuracy to drawing a highway alignment,” “satisfaction withease of use,” and “anxiety.” The research team is taking these issues on board; plans are underway todesign and implement the next-generation TTRS. A TTRS having 256 actuators (16 × 16) is being
designed as compared to the current TTRS (8 × 8); this should improve the accuracy and satisfaction
with ease of use.
Table 1 : The results of the questionnaire (HND and TTRS)

5CodeItem

12345678910111213

Easy to understand the feature of terrain
Accuracy to draw a highway alignment
Easy to understand the 3D positioning of the pointerEasy to manipulate
Realism
Satisfaction with interface
Satisfaction with the ease-of-use
Annoyance
Anxiety
Fun
Intuitive
Learnability
Physical comfort

HMD
Average
STD
1.111
1.054
-0.5561.130-0.222
1.394
0.556
1.130
0.778
0.972
0.333
0.707
0.111
0.928
0.889
1.054
-1.000
0.500
1.667
0.500
0.778
1.202
1.111
0.782
0.111
1.167

TTRS
Average
STD
1.444
0.726
-0.222
1.093
1.222
0.667
1.667
0.707
1.333
0.707
0.556
0.882-0.222
0.833
0.778
0.972
-1.333
0.500
0.444
1.014
1.000
1.000
1.333
0.866
1.000
1.000

Construction of Desktop TTRS

Although the screen size of the TTRS is 60 cm2, its portability is limited. To improve the portability,
we are constructing an improved model of the TTRS that can be used on a desktop. The new TTRS
has a 24.5-cm2 screen that is manipulated by the small type of actuators. The stroke of this actuator is60 mm, and the weight is 60 g. It is expected that portability will be improved. The configuration ofthe new TTRS system is shown in Figure 2.
The basic system is the same as the first prototype of the TTRS. The 3D magnetic tracking system
Polhemus Fastrak is used as a positioning device. The system has a small CMOS camera device thatcan output live-view images on the surface. In Figure 2, an example of the image of the live-view
system is shown. By using this system, a highway designer can acquire landscape images from thepoint on the terrain.
To evaluate the prototype of the desktop TTRS, a small experiment is performed. The experimentis to draw a highway on the TTRS and answer the questionnaire. The subjects are six students fromMiyagi University.

(a) Configuration(b) Drawing(c) CMOS camera(d) Live-view

Figure 2: Desktop TTRS

The result is shown in Table 2. Each score is an average of a five-grade evaluation. In theexperimental evaluation, the ability of drawing a highway is low although a high score is shown for
operability and relief recognition. This result implies that the TTRS with a live-view camera is a very
useful tool for the recognition of the terrain and the landscape. This is an advantage of the new TTRS
as compared to the previous TTRS and the current design method. The subject of this system is toimprove the drawing system using a magnetic positioning sensor, which has some problems related tostable positioning, and to improve the projection system to resolve the shadowing problem by handduring the positioning process.

Table 2. Results of the desktop TTRS experiment
Item
Ability of drawing
Relief recognition from TTRS
Landscape recognition from TTRS
Relief recognition from live-view camera
Landscape recognition from live-view cameraRecognition of matching between relief and highway
Operability

A3455445B
3444335SubjectC D2 24 34 33 42 43 54 5E
2534534F
3455445Average
Point
2.5
4.0
4.0
4.2
3.7
3.7
4.7

6Conclusions

Planning highway routes is time-consuming and demands highly experienced planners. To ensure
accuracy and realism, planners have to imagine the terrain features and possibly assemble a “mental”
3D model of the terrain. This paper describes terrain representation methods and their application thatshould assist planners with imagining the terrain feature and therefore plan highway routes more
effectively and efficiently. Further, the new version of the TTRS, which has a 24.5–cm2 screen isshown and evaluated in this study. The new system has a CMOS camera using which a planner canacquire landscape images as if he/she were present on the terrain.
Tangible technologies have been developed in the recent several years, and these technologies
help the recognition of complicated 3D features such as the terrain considered in this study. Furtherresearch and development is required to develop more advanced systems for highway designing using
these technologies.

Acknowledgements
This research was partially supported by a Grant-in-Aid for Scientific Research from the Japan
Society for the Promotion of Science (JSPS) (C), 17500701, 2005, and the Tohoku Construction
Society. The authors would like to thank Miss K. Agatsuma (Bachelor, Miyagi University) for her
help in the development of the desktop TTRS.

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