1. Student Name: Chung Hiu Lam
Student ID: 09165566d
Q11. It has been argued that off-the-shelf 3D GIS software cannot model the complex
3D cityscape in Hong Kong.Critically evaluate the validity of this argument.
Introduction
Three dimensional modeling popularity has beenraising in Geographical Information
System (GIS) for data analysis and visualization.As A.Scianna(2010) pointed out, the
need for three dimensional feature has been remarkably increased during past few years
in GIS. Usually three dimensions helps to understand data immediately by better
analysis of a situation or a model.1 With advancing technology, many off-the shelf 3D
GIS software become able to create complex 3D model. However, Hong Kong is a high
density city with complex cityscape, which may be difficult for software to model. In
this article, I will evaluate the validity of the argument“off-the-shelf 3D GIS software
cannot model the complex 3D cityscape in Hong Kong”. I will focus the term “model”
to physical modeling.
Cityscape of Hong Kong
According to Oxford dictionaries, cityscape is defined as the visual appearance of a city
or urban area, or similar term as city landscape.2 Other dictionary sources such as
free-dictionary also suggest cityscape as a view of a city, or a section of a city regarded
as a scene.3As a renowned financial center, Hong Kong has complex cityscape with
many irregularhigh-rise buildings. According to Hong Kong Planning department,
Hong Kong is a crowded city with high densities of development, intensive land uses,
low level of vegetation coverage and highly altered topography. Oldest urban area is
located on the north coast of Hong Kong Island and the Kowloon Peninsula, where
buildings are in mixed ages, with some historical buildings and little vegetation lying
between, forming dense and irregular urban form.The reclamation side of Hong Kong
Island and Kowloon lies commercial buildings which are tall and have special shape,
forming a mixed city-grid urban landscape. Extensive residential area with some
1
A. Scianna & A. Ammoscato, 3D GIS data model using open source software. ISPRS Archive Vol.
XXXVIII, Part 4-8-2-W9, “Core Spatial Databases-Upding, Maintenance and Services-from Theory to
Practice” ,p.120, Haifa, Israel, 2010
2
Oxford dictionaries, definition of cityscape: http://oxforddictionaries.com/definition/cityscape
3
Free-dictionary, definition of cityscape: http://www.thefreedictionary.com/cityscape

2. medium and high-rise buildings canbe found at the edge of the urban area.4
Introduction to 3D modeling
As Dan Ryan (2011) mentioned, 3D modeling is the procedure of developing a
mathematical, wireframe model that represents a 3D object using specialized software.
A 3D model is created using a set of points in three axes, X, Y and Z, with linkage of
geometric data such as lines and curved surfaces. 5 3Dmodel can be tangible or
intangible, depending on the representation method.
Most of the3D model creating software uses four methods. They are polygonal
modeling, primitive modeling, NURBS modeling and patch modeling.
Polygonal modeling uses a group of vertices and edges, together with advanced
mathematic algorithm, to generate 3D surface by putting a “skin” over the mesh.6 The
rendering of model is fast but may be difficult to create accurate curved surface.
In constructing 3D model, primitive modeling uses default 3D objects such as cubes
and balls.7 By combining these objects, a more complex 3D model can be produced.
This method is the easiest and simplest as the model is already well defined.
Non-uniform rational B-spline (Nurbs) modeling is similar to polygonal modeling, but
since it joins different spline in space, it is curved based and curved surface is more
smooth and accurate. Patch modeling creates 3D model by stitching square together to
form a pattern. Most off-the-shelf 3D modeling software are using polygonal and
NURBS modeling method to create 3D model.
3D modeling is useful to visualize data, especially concept and idea that is difficult to
represent using 2D model. Through 3D visualization, the model can be viewed in many
ways which represent a problem better. Higher accuracy of the model improves the
ability of using it for analysis and case study. 3D model also provides a lifelike
experience for users, where it is much more interesting and effective for users to view.
3D model procedures
4
HK landscape, by planning department:
http://www.pland.gov.hk/pland_en/p_study/prog_s/landscape/e_executive_summary_hp/es_index.htm
5
Dan Ryan, History of computer graphics: DIr Associates Series, Author House, p.37, 2011
6
Mario Russo,Polygonal modeling: basic and advanced techniques, Wordware Publishing, p.3, 2006
7
Shamms Mortier,The Bryce 5 Handbook, Charles River Media, p.38, 2002

3. To model a cityscape, 3D modeling is not the only process. There are many procedures
which affects the details and accuracy of the model. The first step is data acquisition,
which collects qualitative 3D GIS data for reconstruction. The second step is to use
modeling software to build model in 3D,follow by visualization and analysis of the
model. At last the cityscape is presented using different devices.
Data acquisition
In data acquisition, we focus on collecting qualitative 3D GIS data such that the
accuracy of the model can be improved.Technique such as laser scanning, radar,
thermal and seismic, is frequently used for data acquisition. One of the recent methods
that can produce high quality 3D GIS data is Light Detection and Ranging (LIDAR).
According to Wehr and Lohr (1999), “LIDAR is an active remote sensing technique
that determines the distance between the sensor and the target by accurately measuring
the round-trip time of a pulse of laser energy.”8The application follows laser scanning
technique which creates point clouds of the earth ground. As the light can penetrate
woodland and survey the ground surface accurately, while surface such as concrete
building will be reflected, LIDAR is useful to form a high resolution digital elevation
map and collect building attributes for modeling 3D cityscape.Other methods such as
radar performs a similar process but with different accuracy of 3D GIS data. The main
constraint for these types of data acquisition is that the interior part of the building
cannot be accessed, which means the attribute of inner building is not collected. It is not
possible for modeler to use such data to build 3D cityscape which involves interior part
of the building.
Modeling using 3D GIS software
3D GIS modeling software is essential to build 3D model. 3D GIS software is software
used to create, manage, analyze and display geospatial data on digital maps in 3D. It
should be able to view, explore, create and edit data, store and transform data into
different coordinates systems, analyze data using query on dataset, as a result, create 3D
model that is geometrically correct with newly obtained information from analysis.
Much Off-the-shelf 3D GIS software is available in both commercial and open source.
Some leading 3D GIS software includes Autodesksuite, ESRI ArcGIS, etc. The
following paragraphs introduce different types of 3D GIS software which usermay be
able to create complex 3D cityscape.
8
Wehr A, Lohr U, Airborne laser scanning – an introduction and overview. ISPRS J Photogramm,
p.68-82, 1999

4. AutoCAD and Autodesk 3d Max is software enabling user to design and draft 3D
model. Developed by Autodesk, Inc, it provides primitive model such as box and
for beginners, and produces advanced 3D objects using polygonal modeling technique.
Autodesk continues to improve 3D modeling functions, where editing of 3D model
become easier.Quality rendering is possible with mental ray engine, and objects can
displayed faster and better.9
ArcGIS is an integrated collection of GIS software. Through the geospatial analysis,
data reconstruction and edition, 3D model can be easily produced. For example,
input GIS data into digital map, then select attribute height and extrude, and a simple
3D model within the map area is constructed. A more complex and detailed model can
be built using plug-in such as Google sketch up. In the latest version of the ArcGIS,
functionally of 3D analyst is improved with better face format compatibility and a
accurate 3D object shapes.10
GeoMedia 3D is a 3D GIS software which is focused on geospatial processing for
government, transportation and utilities, etc. User can model and visualize 3D data in
GeoMedia. A more advanced function includes integration of surfaces, imagery,
data and vector data to create 3D model of all data sources.11
3D GIS software which shares little market shares can be powerful too. SpacEyes
builder is software which can represent cartographic data in 3D. It supports input such
as DTM, geo-referenced images and GIS data. Using tools of visualization and
a detailed 3D model is created.12
With many types of GIS format, most software is able to support different standard
format of data such as shape and jpeg.
Visualization of 3D model
After 3D modeling, the next step is to visualize the model. Visualization is an
way to communicate abstract and concrete ideas using visual perceptive such as
diagrams, animations and images. 13Usually 3D modeling software has its own 3D
viewer to visualize and analyze the model. For example, Autodesk 3dmaxhas an
9
Autodesk official website: http://usa.autodesk.com/3ds-max/
10
ArcGIS official website: http://www.esri.com/software/arcgis/
11
GeoMedia 3D official website: http://www.intergraph.com/sgi/products/geomedia3d.aspx
12
SpacEyes official website: http://www.spaceyes.com/index.php?option=com_frontpage&Itemid=99
13
Chaowei Yang,David W. S. Wong,Qianjun Miao, Advanced Geoinformation Science, CRC Press,
p.240

5. inbuilt function to render 3D model and make it as animation or video. SpacEyes has
independent 3D viewer to visualize the 3D model. It is rather a simple task to convert
a 3D model to a view.
3D model presentation
The last process is the presentation of 3D model.Previous section mentioned that
some software is able to render a video to visualize the model. In reality, most of the
company present 3D model through computer and projector, which project the model
to screen in 2D. Some advanced hardware such as 3D projector can project model in
3D. Another method which provides an interactive presentation is 3D printing. 3D
printing is an additive manufacturing technology where 3D object is created by
printing glue onto a powder bed, and forms a 3D structure by successively sticking
thepowder.14 It allows user to touch the 3D model and explore it in detail, which
provides better experience in viewing the model in reality.
Example of 3D cityscape modeling
It is possible to integrate different methods discussed before to model a complex
cityscape.Seattle, a busy city which is located in United States, had conducted project
to visualize the entire cityscape using 3D GIS software. To start modeling, accurate
data is needed. This was collected and processed to AutoCAD and Autodesk 3d max
designing software. Then professionals create buildings, landscape, streetscape and
infrastructure with details in 3D. Afterfine-tuningand 3D rendering, the whole virtual
cityscape is produced and presented on the screen. The 3D model is photorealistic and
is able to help developer analyze problem and make better decision.15
From the previous example, it illustrates the possibility to model complex 3D
cityscape ina crowded city.Although Hong Kong cityscape may be more complicated
than Seattle, where many building heights are unknown and shapes are irregular.It is
possible to use LIDAR to solve the data deficiency and improve data quality, while
modeling software is able to model complex 3D object. For example, bank of China
has irregular building shape, the 3D model can easily be found in 3D warehouse.It
14
Ian Gibson,David W. Rosen,Brent Stucker, Additive Manufacturing Technologies: Rapid Prototyping
to Direct Digital Manufacturing, Springer, p.30, 2010
15
Parsons Brinckerhoff, Seattle Design Visualization, Autodesk Inc:
http://usa.autodesk.com/adsk/servlet/item?siteID=123112&id=15834513

6. draws a conclusion that off-the-shelf 3D GIS software is able to create 3D cityscape,
attributes such as building heights, materials,infrastructure and landscape are well
presented.
Arguments for the statement
It follows a question on how detail the buildings are in the 3D model. One of the most
difficult problems to model Hong Kong cityscape is that there are many mixed-use
buildings.For example ground level is in commercial use while the upper part is
residential area.The floor area and façade is different and is troublesome to model it.
Also, one of the most famous scenes in Hong Kong is the streetwith full of neon sign
and advertisement banner. It is extremely hard to include all signs in the model.
Another concern would be the scale of the project. Cityscape can be small or large
depending on the project scale. Large scale project tends to use more time and
resource, and not all organization could afford the cost.These constraints may be
solved by investing more time and money to collect data and develop the model, and
manage the project within suitable scale. The final problem comes with the perceptive
of 3D model. Most of the methods above visualize exterior part of the cityscape,
which means only concern the outer part of the building. However, perceptive of
cityscape from the interior part of building should also be considered to produce a
lifelike experience using the model. Currently not much 3D GIS software could
model interior part of the building easily, or it is rare to see company using interior
part to represent a cityscape.
Conclusion
To conclude, to a small extent I think off-the-shelf 3D GIS software cannot model the
complex 3D cityscape in Hong Kong. From the article we discuss the most important
steps in 3D modeling, where accurate data can be collected by using LIDAR.3D
modeling, visualization and analysis can be done by different 3D modeling software,
and be presented using different output devices.The remaining problem lies on how
detail the model should be and what perspective the model should be at. Therefore, as
long as you have accurate GIS data, enough time and money, technically it is possible
to model the complex 3D cityscape in Hong Kong.