About Spatial Data
Coordinate Systems
Area of Interest
Update Frequency
Format
Number of Users/Seats
Customisation
Additional Services
Coordinate Systems
A coordinate system is made up of a datum and a projection.
A datum describes the size and shape of the earth and in Victoria,
the datum will typically be GDA94 or AGD66. A projection is
based on a datum and is the mathematical transformation linking
points on the curved surface of the Earth to complementary
points on another surface, usually a flat map plane. If you
have ever tried to flatten the skin of an orange you would
have realised that it is impossible to transform from a curved
surface to a flat surface without shrinking some portions
and stretching others. This is the basic problem of map projections
and accounts for the many and varied types of projections
which are the result of attempts to minimise distortions.
The list of coordinate systems offered are the most suitable
(and most commonly used) for Victoria and so most relevant
for the Vicmap Digital data. Please contact Spatial Vision
if you wish to select a type of Coordinate System that is
not listed. Spatial Vision can advise you on the optimal coordinate
system for your requirements if you are unsure. For more details.
On Coordinate Systems http://www.auslig.gov.au
On Why GDA? http://www.anzlic.org.au
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Area of Interest
The area of interest is that area in Victoria for which you
would like any of the Vicmap Digital data supplied. There
are several ways of selecting this area. It may have distinct
boundaries that already exist such as map sheets or local
government or other administrative boundaries. You may know
the coordinates of the area in question or you may have a
looser definition, for example 'the north-western quarter
of the state' or 'the area east of Traralgon'. Whichever method
you use to select the area of interest you will be supplied
data only for this area. For this reason it is sometimes a
good idea to add a 'buffer' around your area of interest,
to ensure that you fully encompass your area and don't risk
missing out data that may be important at the edges. Once
you have chosen your area of interest and purchased Vicmap
Digital data for that area, Spatial Vision will keep the area
on file for your future Vicmap Digital (and other) data requests.
To choose an area of interest.
By Map Sheet:
To choose by Map Sheet you will need to know the map series
and the map sheet name or map sheet number.
By Feature Boundary:
To choose by Feature Boundary you will need to use a common,
well-known Victorian boundary feature. The most common boundaries
are metropolitan Melbourne, local government areas, catchment
boundaries and parishes.
By Bounding Box:
To choose by Bounding Box you will need to enter four coordinates
which delineate the upper left x and y and lower left x and
y coordinates of a box.
By Graphic:
Your area may be more loosely defined and not fit into any
distinct boundaries. You may choose to highlight the area
on a map of Victoria to send to us. If none of the methods
suit you, Spatial Vision will be happy to assist you in choosing
your area of interest.
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Update Frequency
Each of the Vicmap Digital products is updated to reflect
dynamic changes and improvements. However, the rate of change
and availability of updates varies for each data product.
For example the Vicmap Property and Address data changes most
frequently, as sub-divisions are created every day. Whereas
data such as Vicmap Hydrography (river and streams) is not
dynamic but updated over time with enhancements. Spatial Vision
recognises the need for you to have the most up-to-date data
as practical and offers to provide you with updates. You have
the flexibility to choose the update frequency for each of
your Vicmap products. Spatial Vision can advise you on availability,
formats and impacts of updates for each Vicmap data product.
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Format
Spatial Vision supplies data in ESRI, MapInfo and CAD formats.
We are happy to discuss other formats that you may be interested
in. Spatial Vision can advise you on the appropriate format
for your requirements if you are unsure.
■ ESRI
Geodatabase
ArcSDE Export
ArcInfo .e00
ArcView Shape
■ MapInfo
.TAB
.MID/MIF
■ CAD
.DXF
.DWG
.DGN
■ Imagery
.TIF
.BIL
.ECW
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Number of Users
The licence cost for Vicmap data is dependent on the number
of users in an organisation with access to use the digital
data. Each user with access is counted to calculate the final
licence cost. The cost per user is discounted as the number
of users increases.
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Customisation
Spatial Vision staff have extensive experience in distributing,
managing and value-adding Vicmap Digital data as well as other
geospatial data. This experience has provided our staff with
a thorough understanding of the potential uses, limitations
and benefits of the State digital map base. We also have extensive
expertise in database design, integration into business data
applications, implementation of geodatabases, spatial analysis
and map product generation, and can advise you on how to maximise
your investment in Vicmap data. Contact Spatial Vision to
discuss how we can customise your data.
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Additional Services
Given our wealth of experience with spatial information
we can offer you a range of supporting services including:
■ capture or conversion of data from field or map sources
■ undertake quality assessments of spatial data against
national or business standards
■ packaging spatial data with friendly distributed GIS viewers
■ searching for and supplying other available digital data
■ providing advice on infrastructire and strategies for
effective management and deployment of spatial data
We also have extensive knowledge of other DSE geospatial
data, notably the Corporate Geospatial Data Library (CGDL)
and can advise you on it's availability. For any questions
on spatial data, contact Spatial Vision.
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Copyright © Spatial Vision, Tuesday, 24-September-2002 |
