Title

Vicmap Position - AGD66 and GDA94 Transformation Sample Point 

Alternate title

TRANSFORM66_94 

Purpose

Validate software and data used to transform Land Victoria's data from AGD66 to GDA94 datum. 

Credit

The data set selection, test design, software management and output validation is credited to: Geoff Parkes Land Information Group Ross Honeyman Land Information Group Dr Philip Collier Department of Geomatics Melbourne University Martin Hale LIG 

Supplemental Information

Related Documents: None 

Status

Completed  

Code

4283 

Maintenance and update frequency

As needed  

Topic category

• Geoscientific information

Use limitation

The test data is not to be referred to by users as verifying compliance with NRE or ICSM standards. 

Classification

Unclassified  

Statement

Dataset Source: The data was processed initially in June 2002 by the Land Information Group and later verified by, the Department of Geomatics, University of Melbourne in the same month. Dataset Originality: Primary 

Classification

Unclassified  

Attribute Quality

Comments

1:1 

Positional Accuracy

Comments

Datum transformation and coordinate conversion was verified at the submillimetre level. 

Conceptual Consistency

Comments

submillimter 

Missing Data

Comments

The data set covers the state of Victoria and immediate surrounds and consists of 160 points spread across the state of Victoria and includes 60 points sourced from the (ICSM) 'Sample AGD66 - GDA94 Transformation' points set contained in the file Transtest.xls found in the GDA Technical Manual (http://www.anzlic.org.au/icsm/gdatm/). The sub set of ICSM points are located in and immediately around the state of Victoria. Completeness Verification: This data set was generated by Land Victoria staff using FME (Build 444) configured to use the AGD66/GDA94 NTv2 grid file 'A66 National (13.09.01).gsb'. The starting data were AGD66 geographicals in decimal degrees to 15 decimal places. The actual values supplied as input to FME were the latitude and longitude coordinates expressed in decimal degrees. These were computed from corresponding degrees, minutes seconds values prior to being fed into FME. Coordinate pairs were then computed directly from these AGD66 geographical values using FME's @eproject function. The FME outputs were then verified by a member of the Department of Geomatics, University of Melbourne by comparison with GDAit and GDAy transformation software (refer to ICSM GDA web site at www.anzlic.org.au/icsm/gdatm/index.html) and formulae derived from first principles as follows: 1. Geographical coordinates The GDA94 latitudes and longitudes produced by FME were compared to results from both GDAit and GDAy. A perfect agreement to 9 decimal places of degree resulted. The number of significant decimal places for mathematical comparison was selected to ensure reliable backwards and forwards transformation processing could be performed such that the position solution would not degrade after many transformations between datums at the submillimetre level. 2. Universal Transverse Mercator Projection coordinates The MGA94 coordinates produced by FME were then compared to the results from GDAit and GDAy with small discrepancies ranging up to about 0.3 mm between all three solutions. It is believed that these differences are likely to be the result of a small rounding affect caused through the conversion from geographicals to map grid. These differences are not considered to cause concern for users. 3. VicGrid Vicgrid66 transformations where verified by comparing FME results with results obtained via ESRI's ArcInfo project file command. Vicgrid94 transformations were verified by comparing FME results with Phil Collier's testing process. Agreement was verified at about 0.1 mm. (refer to www.giconnections.vic.gov.au for vicgrid parameters). 

Excess Data