1. LSGI4321 Essay Chan Tsz Ying Sakina (10595489D)
Topic: To facilitate forward planning and development control, planners have been
using remote sensing techniques to understand the existing land use
pattern. However, critiques have argued that “… Despite the promise of new and
fast-developing remote sensing technologies, a gap exists between the
research-focused results offered by the urban remote sensing community and the
application of these data and products by the governments of urban regions.”
(Netzband et al., 2007). Critically assess the validity of the above statement
suggested by Netzband et al. 2007.
It is known that remote sensing is applied in many applications. There are many
articles, journals and books discussing how remote sensing is useful to urban
development. However, Netzband et al. 2007 states that “… Despite the promise of
new and fast-developing remote sensing technologies, a gap exists between the
research-focused results offered by the urban remote sensing community and the
application of these data and products by the governments of urban regions.” Their
view point is quite different from the general cognition towards remote sensing
application for urban planning. This essay is to critically assess the validity of the
statement. Reasons for validating this statement would be discussed. Also, some
recommendations would be given in order to improve the situation.
Generally speaking, the remote sensing data and products are independent,
up-to-date and available from anywhere around the earth. Also, the products are
reproducible, consistent and comparable (Taubenböck, H. & Dech, S., 2010). Remote
sensing technology has many applications. One of the examples is urban
development. Urban development includes urban planning, urban monitoring and
land use or land cover type classification. These applications can facilitate the
government to analysis the city and make better planning. The government wants to
obtain the land use or land cover information in order to analyze the existing land
use situation first before design any plans. This can be achieved by satellite images
and classification is needed to identify the land cover of each pixels. Remote sensing
can obtain the earth’s image fast and temporally. This can allow change detection
over the same area within a time period. However, is it true that the
research-focused data and products meet the needs of the regional government for
urban development?
Urban area is so special that it is a combination of social, economical and natural
area. Since land resources are limited and valuable, so effective planning is needed in
order to develop the city in accordance with the city characteristics. According to

2. LSGI4321 Essay Chan Tsz Ying Sakina (10595489D)
Wikipedia (2011), urban planning includes ten different aspects, examples are safety
and security, transport and economics. Therefore, the governmental department
which is responsible for urban development needs many different types of data to
assist their work. Data like the needs of the citizen, population growth,
transportation flow and road network accessibility cannot be provided by remote
sensing. It is obvious that the remotely sensed data cannot reveal this kind of
information and not applicable in this aspect. This is one of the reasons why there is
a gap between research-focused remotely sensed data and government use.
More importantly, remote sensing can only provide data. What make the data useful
is how to convert the data into useful information for different end users and for
different applications. According to the Steering Committee On Space Applications
and Commercialization (2001), remote sensing data can initially be complicated and
even irrelevant to potential end users who make policy and management decisions.
This kind of users need easily understood information which can be used to address
economic, social, environmental, and other policy questions. Obviously, what
Netzband et al. state is due to the fact that the researchers do not really know the
needs of the end users. The end users stated by Netzband are governments of urban
regions. Different cities and regions have different topology, culture and policy. What
they need is the information useful for their specific urban development.
Different cities have different approaches for urban planning. For example, some
cities want to focus on the sustainable development. The cities would like to
preserve the agricultural land in the urban fringe. Then, their needs for the data is
not just showing the current urbanization situation, but also the predictions. The
remote sensing community should focus the research on monitoring and predicting
the trend of urbanization in order to provide useful information of the local
government to make better plans. This is the reason why remote sensing cannot help
much in forward planning. Let’s take one more example. Consider a city which wants
to protect and preserve the ecosystem in urban area. There is a lack of reliable base
data to assess the ecosystem health and biodiversity of many urban cities because
urban area is too mixed. It is hard to identify the micro ecosystem. Also, remote
sensing cannot differentiate the forest, freshwater habitat, natural and semi-natural
grassland (Borre, J. V. et al., 2010). Remote sensing cannot meet the need of
monitoring the environmental change due to urbanization. Other technology is
needed rather than remote sensing.
Take Hong Kong as another example. Hong Kong is a crowded city with lots of

3. LSGI4321 Essay Chan Tsz Ying Sakina (10595489D)
mountainous area and many people. Shortage of land and housing is a long term
problem in Hong Kong. Town planners need to think of how to explore the new land
for development and preserve the mountain ridge the Victoria Habour view at the
same time. The planning department in Hong Kong needs detail and accurate land
use classification. However, the remote sensing images are limited with more than 2
meters per pixel. Still, classification result may not be accurate for a 2-meter pixel. It
is possible to have several land use within a pixel in Hong Kong, especially areas like
Sham Shui Po. Remotely sensed data is not very useful to a high density city. Another
situation is when there is unauthorized development. It is hard for the government
to sue the owner using satellite image as the evidence because the resolution of the
image is not high enough to identify the building.
Another factor causing the remotely sensed data not applicable is the intellectual
property of the data. Due to the intellectual property right, the cost of purchasing
the data becomes higher. According to Steering Committee on Space Applications
and Commercialization (2001), there is a growing trend toward licensing rather than
selling commercially produced databases. So the terms for use of the data are
controlled by the terms of the license. Successive uses of the same data could
become very costly. This expense may become a hindrance using remote sensing
data. Moreover, if the government bodies want to share the data to the general
public, they may not be allowed because it is possible that the private remote
sensing service providers control the number of users. Multiple users may need to
pay for extra money.
Sometimes, the remote sensing data or products cannot meet the need of regional
planner is due to the fact that remote sensing technology has its limitations. Many
researchers in the remote sensing field are focusing on how to solve these problems
because these limitations would lower the quality of the remote sensing products
and limit the applications. The following would discuss about limitations like
relatively low spatial resolution, cloud cover and shadow problem and atmospheric
absorption.
There is always a tradeoff between spatial and spectral resolution of satellites. A high
spectral resolution is coupled with a low spatial resolution and vice versa. For
example, GeoEye-1 is the commercial imaging system launched on September 6,
2008 by the U.S. It has the highest spatial resolution compared with similar system at
the moment. It can collect images with a ground resolution of 0.41 meters in the
panchromatic imagery and it collects multispectral imagery at 1.65 meters resolution.

4. LSGI4321 Essay Chan Tsz Ying Sakina (10595489D)
However, it only has four bands including red, blue, green and near infrared in the
multispectral imagery (GeoEye-1 Launch Site | About GeoEye-1, 2011). Contrastingly,
Earth Observing 1 (EO-1) is a satellite sensor launched on November 21, 2000 by the
U.S. It is the hyperspectral sensor with the highest spectral resolution. It contains 220
bands but each band has only 30 meters ground resolution (Characterization of
Satellite Remote Sensing Systems | Satellite Imaging Corp, 2011). These two
examples show that we cannot obtain satellite image with high spatial and spectral
resolution at the same time. Although satellite image can provide a relatively large
pixel size, this is still not enough for some urban planning application. Take Hong
Kong as an example, Hong Kong’s urban area like Mong Kok, is very crowded with
mixed land use. Even 2-meter pixels are hard to classify the land cover type.
Cloud cover and shadow is the big problem in optical remote sensing, the problem is
especially serious in the humid tropical region. Clouds would hide the features on the
ground. Also, its shadow would cast on the ground. If the clouds do not be removed
from the image, it will affect the result of classification. To mask out the cloud from
the image, automated cloud masking is used by many researchers. However, simple
thresholds cannot handle thin clouds and cloud shadows, and often confuse bright
land surfaces as clouds (Li, M. et al., 2003).
Beside cloud cover and shadow, atmospheric absorption is another unavoidable
problem for remote sensing. Atmospheric absorption appeared when the
atmospheric particles absorb the signal from the satellite. Beside absorption, the
atmosphere will reflect, refract and scatter the energy. This problem causes the
reflected signal from the features on the ground back to the satellite weaken. The
digital number (DN) value would be affected. This can be adjusted by atmospheric
correction. Atmospheric correction is important preprocess of image classification. If
the pixel value is not accurate, many analysis works would be affected.
It is inevitable that there is a gap between the regional governmental users and
research-based remote sensing products. Then what should be done is to narrow
down the gap. The following are some suggested solutions.
First, the researchers need to understand the need of the government. Regular
meetings or conferences can be held for the two parties in order to understand the
recent developments so that they can cooperate with each other. Like Hong Kong,
the planning department can cooperate with the Chinese University of Hong Kong
and the University of Hong Kong. The Institute of Space and Earth Information

5. LSGI4321 Essay Chan Tsz Ying Sakina (10595489D)
Science from the Chinese University of Hong Kong has the Satellite Remote Sensing
Receiving Station. The station can capture and process satellite-sourced remote
sensing data and provide information that is useful to Hong Kong. On the other hand,
the Department of Urban Planning and Design of the University of Hong Kong
provide education of urban planning and design. The planning department can
understand the academic research directions or area of the institutes and the
academic sides can understand the concerns of the government and the academic
researchers can assist the town planners for better development of Hong Kong.
Nothing in the world is perfect. Remote sensing technology has its limitation, but it
still has many advantages that the regional government departments for urban
development can make use of it. Remote sensing can obtain the earth data within a
large area quickly and temporally. Although the spatial resolution is not very high, it
can act as the base information and integrate with different data sources like
topological survey, aerial photographs or overlay with different satellite images for
analysis. This can complement different technologies’ limitation and make the
derivative products useful for urban development. Investment by the government is
needed to provide long time training for the technicians, prepare hardware and
software and data acquisition. (Steering Committee on Space Applications and
Commercialization, 2001)
To conclude, it is valid for Netzband et al. (2007) who state that “there is a gap
between the research-focused results offered by the urban remote sensing
community and the application of these data and products by the governments of
urban regions.” The reasons are the lack of understanding and communication
between the remote sensing researchers and regional governmental end users. Also,
the intellectual property of the remote sensing data may cause the data costly. The
limitations of remote sensing technology affect the quality of the data and thus
lower the effectiveness of these data to urban development application. What
should be done is to strengthen the collaboration between the remote sensing
community and the governments. Also, the government can try to integrate the data
obtained by different technologies like surveying and photogrammetry with the
remote sensed data to derive a more useful data for urban planning.

6. LSGI4321 Essay Chan Tsz Ying Sakina (10595489D)
Reference
Borre, J. V., Paelinckx, D., Hoffmann, M. Spanhove, T. (2010). Biodiversity Monitoring
Beyond 2010: What Role For Remote Sensing?
Characterization of Satellite Remote Sensing Systems | Satellite Imaging Corp(2011).
Retrieved November 5, 2011 from
http://www.satimagingcorp.com/characterization-of-satellite-remote-sensing-system
s.html
GeoEye-1 Launch Site | About GeoEye-1 (2011). Retrieved November 18, 2011 from
http://launch.geoeye.com/LaunchSite/about/Default.aspx
Li, M., Liew, S. C. & Kwoh, L. K. (2003). AUTOMATED PRODUCTION OF CLOUD-FREE
AND CLOUD SHADOW-FREE IMAGE MOSAICS FROM CLOUDY SATELLITE IMAGERY.
Steering Committee on Space Applications and Commercialization (2001).
Transforming Remote Sensing Data into Information and Applications
Taubenböck, H. & Dech, S. (2010). Remote Sensing and Urban Planning - A Common
Future?. Retrieved November 19, 2011 from
http://www.vector1media.com/article/features/13931-remote-sensing-and-urban-pl
anning-a-common-future-.html
Wikipedia (2011). Retrieved November 18, 2011 from
http://en.wikipedia.org/wiki/Urban_planning#Aspects