Mapping and Cartography

Y. C. Chan

Mapping

Wikipedia

◦ Mapping is creating graphic representations of

information using spatial relationships within the graphic to represent some relationships within the data. The common and original practice of mapping is the

scaled portrayal of geographical features, that is, cartography. In the contemporary sense of data

visualization, it includes metaphorical extensions of geographical map conventions and literacies to other kinds of data, as well as innovative ways of visualizing data not clearly related to the geographical archetype. In popular vernacular, mapping can just mean organizing or systematizing information.

Cartography Wikipedia

◦ Cartography is the study and practice of making maps. Combining science, aesthetics, and

technique, cartography builds on the premise that reality can be modeled in ways that

communicate spatial information effectively.

◦ Fundamental problems of traditional cartography are to :

◦ Set the map's agenda and select traits of the object to be mapped. Traits may be physical, such as

roads or may be abstract, such as boundaries.

◦ Represent the terrain of the mapped object on flat media. This is the concern of map projections.

◦ Eliminate characteristics of the mapped object that are not relevant to the map's purpose. This is

the concern of generalization.

◦ Reduce the complexity of the characteristics that will be mapped. This is also the concern of

generalization.

◦ Orchestrate the elements of the map to best convey its message to its audience. This is the

concern of map design.

◦ Modern cartography is largely integrated with geographic information science (GIScience) and

constitutes many theoretical and practical foundations of geographic information systems.

Cartography

HKIS Website Maps are the best tools to represent details on the surface of the earth. To produce a

lucid and informative map, professional knowledge and judgment in the selection of data, visualization and presentation of information are critical. Cartography is one of the specializations in the field of land surveying involving the

abstraction, manipulation, analysis and presentation of the

phenomena and relationships that occur in the real world. Land surveyors specialised in the subject must familiarize with the nature and accuracy of data for map production, and have the graphic design sense to present map data on various media such as paper, internet, mobile phone or even Personal Digital Assistant (PDA). In a wider scope, the application of cartography facilitates decision making, public administration, planning and monitoring of infrastructure through the interpretation of the media. Nowadays, the land surveyors specialized in the subject plays a more important role of

designing a comprehensive mapping database. With the advent of new computer technologies, mapping database facilitates paper map publication in various scales, themes and formats on various platforms and applications.

Mapping

Map?

Mapping

A map is a visual representation of an area – symbolic depiction highlighting relationships between elements of that space such as objects, regions, and themes.

Scale?

Projection?

Orientation?

Accuracy?

Updateness?

….

Mapping in Hong Kong

Survey and Mapping Office (SMO), LandsD

Major Role:

• establishment and maintenance of a geodetic network;

• provision of land boundary (cadastral) surveys,

photogrammetric survey as well as cartographic and

reprographic services;

• maintenance of a computerised land information

system for mapping data and land boundary records;

• production and revision of maps and plans at different

scales for different purposes; and

• administration of the Land Survey Ordinance (Cap. 473).

Mapping in Hong Kong

If you are going to prepare a map series, what will be

your consideration in the map design?

• Purpose (basic map, thematic, topographical, topological…)

• Scale

• Datum (HK 1980 Geodetic Datum)

• Projection (UTM, 1980 Grid)

http://www.geodetic.gov.hk/smo/gsi/data/pdf/explanatorynotes.pdf

Projection parameters (e.g. Ellipsoid, Scale Factor…)

• Cartographic presentation (e.g. naming convention, symbology,

generalization…)

• Paper vs Digital (map design can be different)

Mapping in Hong Kong

• Black and White/Colour

• 2D vs 3D

• Format? (Raster/Vector, CAD/GIS, Open

source/proprietary)

• Delivery : paper – printing (e.g. 4-colour process

printing? CMYK?)

Mapping in Hong Kong

Some update : 3D Spatial Data available from Oct 13

A territory-wide 3D Spatial Database (3 types of ground objects)

• Building

• Infrastructure

• Terrain

Common platform/standard

• Enable data exchange

• Enable data sharing

Can speed up decision making in relation to environmental, planning, lands, works…etc.

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3D Spatial Data (Virtual HK)

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L1 Building Model

Virtual HK with highest

levels of details

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3D Spatial Data (Virtual HK)

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3D Spatial Data (Virtual HK)

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3D Spatial Data (Virtual HK)

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3D Spatial Data

(enabling different applications)

Inundation Map Environment Impact Assessment

Preliminary obstacle/terrain assessment

View analysis for land valuation

Virtual flying training

Mission planning

Change Detection

Building Information Modeling

Application Examples :

View Analysis (e.g. for Valuation) [demo]

Presentation of engineering proposals

Airflow Study

Traffic Noise Assessment

3D Spatial Data

Mapping and Cartography

• Personal Sharing

• Art, Science or both?

• Interlocking with other areas in surveying?

• Conventional or contemporary?

• Web Map or GIS?

• 2D or 3D?

• Symbolization, Photo-realistic or Photo?

• Updating?

• Thematic or Multi-purpose?

Utility Surveying

Utility Surveying

HKIS Website Utility surveying is an emerging profession in Hong Kong and worldwide.

underground utility’s spider networks :

◦ water supply

◦ drainage

◦ Sewerage

◦ Power

◦ Gas

◦ telecommunication pipes and cables

extends the land surveying discipline from above ground to characterization of underground or subsurface.

increasing awareness of tragedies which have been caused by insufficient monitoring and maintenance of underground utilities.

◦ E.g. landslide which happened in Kwun Lung Lau on 23 July 1994, triggered by constant water seepage due to defective drainage network buried in the slope.

Utility Surveying

HKIS Website Following this disaster, the demand for surveys of underground utilities attracted wide attention, and

standards and regulations have been enforced to define and regulate utility surveying practices, not only in water supplies and drainage, but also in gas and power cables.

◦ For example, the Code of Practice on Monitoring and Maintenance of Water Carrying Services Affecting Slopes was initially enacted in 1996 and revised in 2006.

◦ Another two examples are the Gas Safety Ordinance and Electricity Supply Lines (Protection) Regulation was enacted on 1997 and 2002 respectively. The cases of gas and power cable require cable to be detection prior to excavation, in order to ascertain their existence, alignment and depth.

At present, the demand of utility surveying is not only about safety, but also extends to detail 3D underground/subsurface mapping with precise land surveying technologies, and customization of the information from different utility undertakers into unified database using GIS.

This profession strives to provide solutions that help to solve a range of underground utility problems at different stages, from

◦ (1) initial systems and design, then

◦ (2) intermediate surveying and construction, and

◦ (3) long term monitoring and maintenance, data, operational and asset management.

Hong Kong is very much in short of such properly trained utility specialists that can integrate the spatial above-ground and underground information. It is anticipated that more qualified utility specialists are in urgent demand due to persistent urbanization and underground utility projects.

Utility Surveying

Typical jobs ◦ Conduit/Pipe/Manhole Condition

◦ Identification of Underground Utilities (e.g. Power, Cable, Gas, Water, Drainage & Waste Pipe)

◦ Leakage Detection

◦ Void Detection

◦ Flow Study

◦ …

Utility Surveying

Typical Instrument/Method ◦ Conduit/Pipe/Manhole Condition

CCTV

◦ Identification of Underground Utilities (e.g. Power, Cable, Gas, Water, Drainage & Waste Pipe) Ground Penetration Radar (GPR)

◦ Leakage Detection CCTV

Leak Noise Correlation (LNC) Survey

Pressure Monitoring

◦ Void Detection Ground Penetration Radar (GPR)

◦ Flow Study Levelling, survey current using dye/drogue

Utility Surveying

CCTV

◦ Condition Survey

◦ Leakage detection

Utility Surveying

Ground Penetration Radar

◦ Identification of Underground Utilities (e.g.

Power, Cable, Gas, Water, Drainage & Waste

Pipe)

◦ Void Detection

Utility Surveying Ground Penetration Radar

◦ Geophysical method that uses radar pulses to image the subsurface.

◦ Nondestructive

◦ Microwave band

◦ Detects the reflected signals from subsurface structures.

◦ Can be used in a variety of media e.g. rock, soil, ice, fresh water, pavements and structures.

◦ Detect objects, changes in material, and voids and cracks.

◦ GPR uses high-frequency (usually polarized) radio waves and transmits into the ground. When the wave hits a

buried object or a boundary with different dielectric constants, the receiving antenna records variations in the reflected return signal.

◦ Similar to reflection seismology,

electromagnetic energy vs acoustic energy,

reflections appear at boundaries with different dielectric constants instead of acoustic impedances

◦ The depth range of GPR is limited by the electrical conductivity of the ground (conductivity increases, the penetration depth decreases, energy dissipation)

the transmitted center frequency; and

the radiated power.

◦ Higher frequencies, less penetration, higher resolution

Utility Surveying

Safety

◦ Occupation Safety and Health

E.g. Code of Practice - Safety and Health at

Work in Confined Spaces

◦ Gas Safety Ordinance

◦ Electricity Supply Lines (Protection)

Regulation

E.g. Competent Person

◦ …