About Map Data
What is map data?
Maps are produced from data collected over many years and from diverse sources, including satellite imagery, local councils and land holders, state mapping agencies, field investigations, commercial map producers, government agencies and the general public.
This data is held in a variety of databases with specific software used to extract and manipulate the data to produce maps. Mapping is a complex and specialised activity and Geoscience Australia provides much of this data for free or for a nominal cost, allowing other map producers and organisations to use the topographic data in their own projects.
We have approximately 130 Gigabytes of base topographic data. There are approximately 1000 datasets for the various themes and features that complete our mapping data repository, each with a specific purpose for incorporating into products as required. Data can be supplied in a variety of formats to end users, including printed maps and Geographic Information System (GIS) formats.
New and evolving data delivery methods are becoming available, including MapConnect our online topographic and geological map download facility, and geo-referenced PDF digital maps.
Geographic Information System (GIS) data
Digital spatial data, or Geographic Information System (GIS) data, is a digital representation of the real world. Spatial objects such as points, lines and polygons are used to depict spatial features:
- points are used to depict point features such as buildings or locations
- lines are used to depict linear features such as roads or drainage
- polygons are used to depict area features such as water-bodies or parks.
The spatial objects are linked to attributes that describe the features and phenomena that exist at those locations.
GEODATA is our range of digital data products designed specifically for use in geographic information systems (GIS). The following scales of topographic data are part of the GEODATA range: 1:100 000 for the ACT Region; 1:250 000; 1:2.5 million; 1:5 million; and 1:10 million.
While GEODATA is designed for use in GIS, for applications such as polygon overlay and network analysis, the data are flexible enough to be transformed into other formats to allow their use in computer aided drafting (CAD) packages, non-graphic databases and spreadsheet applications.
All GEODATA products are:
- GIS compatible: every GEODATA product is designed to be immediately useful within GIS. You save the expense of bringing the data up to standard. For vector products, this means the adoption of a suitable data model and exacting standards for topological integrity
- nationally consistent: each GEODATA product adheres to a consistent, national specification. As a consequence, each product offers consistency in the treatment of features and attributes, the criteria for feature selection, the positional and attribute accuracy, and the data point density
- quality: all products undergo tests on vital aspects such as topological integrity, completeness, and positional and attribute accuracy
- comprehensively documented: comprehensive documentation accompanies all GEODATA products, allowing you to determine whether a particular product is suitable for your application and to ensure you realise maximum value from the data
Other data products
Geoscience Australia began capturing digital map data in the early 1970s, primarily for map production purposes. The data have a structure and graphical accuracy well suited to the reproduction of maps at the same or smaller scales to the source material. However, the data may vary greatly in quality depending on the method of capture and digitising specifications in place at the time of capture. These data are best suited to graphical applications.
Products not complying with the GEODATA standard use the geometric objects of points and lines to provide map detail. Points are used to depict point map features or symbols, while lines are used to depict linear features such as roads and rivers or to delimit the boundaries of area features such as lakes and large buildings. The cartographic feature represented by the point or line is given by a feature code.These map data are most suitable for use as a graphical backdrop but can be used for more sophisticated GIS applications after some restructuring by the user. Such products include the non-GEODATA 1:100 000 data and various thematic data.