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Open Street Map (OSM)
By Liz Dodd
A project to apply open source principles to maps
Underlying Principles
- Almost all cartographic data is under copyright.
- The features that maps show are not under copyright.
- Many hands make light work.
Benefits
- Free (as in beer) and free (as in speech) cartographic data
- In places that are actively mapped, the most up to date street data in existence.
Current Standing
- nearly 39,000 users
- 250 million road sections
- 20 million road corners
- While some countries have been filled in with government datasets, the majority of this work has been done by individuals
Click here to see an animated image of the growth of OSM data in Australia.
South West NSW - Landsat Griffith – Landsat
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How to help
- Find a free data source
- Get a copy of an OSM editing tool
- Convert your data to a form that OSM can use
- Upload to the server
Data Source: GPS
- GPS is the Global Positioning System
- American military owned network of satellites each transmitting an individual repeating signal
- A receiver detects these signals, and knows the pattern of each satellite. With 4 satellites it can calculate the most likely distance to each one
- Position fixing by trilateration
GPS Accuracy
- GPS is the Global Positioning System
- A handheld GPS is accurate to 5 – 10 metres horizontally and 10 – 20 metres vertically, provided no other errors are in place
- PDOP, Multipathing, Ionosphere, Ephemeris and Signal Definition are examples of errors in the GPS system
- All GPS errors vary with time
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