Geodetic Calculations Methods

• Distance Calculations
• Calculate Bearing & Distance from Latitude & Longitude
• Convert from Latitude & Longitude to UTM coordinates
• Transformation of Coordinates

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Online Calculations & Downloadable spreadsheets
- to perform Geodetic Calculations

Detailed information about the spreadsheets and formulae used in all calculations listed below can be found in the Geocentric Datum of Australia - Technical Manual.

Note: Read the documentation describing the distance calculation algorithms to decide which method best suits your requirements.

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Distance Calculations

Calculate Great Circle distances using latitude and longitude

• Online version
• Great Circle Calculator - "As the Cocky Flies"
• MS Excel spreadsheet which calculates distances using two different simplified methods - Great Circle & Approximate Ellipsoidal.

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Calculate Bearing & Distance from Latitude & Longitude

Use Vincenty's formulae to calculate distance and bearing from latitude & longitude and vice versa

• Online version
• Vincenty Direct
• Vincenty Inverse

• MS Excel spreadsheet
  NOTE: Please have the Excel program "Tools|Options|Calculation|Iteration" box selected so you do not get a circular reference in this file.

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Convert from Latitude & Longitude to UTM coordinates

Use Redfearn's formulae to convert between latitude & longitude and UTM coordinates and vice versa

• Online version
• Grid to Geographic
• Geographic to Grid

• MS Excel spreadsheet

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Transformation of Coordinates

The following are available for download but are not yet available as online calculations.

• High Accuracy Transformation Grids - Recommended method (only available for use within Australia)
• Download Software and Transformation Grid Data to transform from AGD66 & 84 to GDA94. Select options from left side navigation bar of Geocentric Datum of Australia home page

• Medium Accuracy 3-Dimensional Similarity Transformation
• MS Excel spreadsheet which computes a similarity transformation, and converts between geodetic coordinates and Earth-centered Cartesian coordinates - (latitude, longitude, ellipsoidal height <-> X Y Z)

• Low Accuracy Molodensky's method
• MS Excel spreadsheet which transforms between AGD66 & 84 and GDA94

• Low Accuracy Block Shift
• MS Excel spreadsheet for average size of the block shifts between AGD66 & 84 and GDA94, computed for 1:250 000 topographic map areas across Australia.

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