Geodetic Calculator Spreadsheets
This is a suite of spreadsheets, which have been modified slightly from those available at the Geodetic Datum of Australia Technical Manual to perform calculations on the ACT Grid.
Please note the conditions of use attached to these spreadsheets
Combined Scale and Height Factors
This spreadsheet has been developed from the NSW LPI’s product. As well as calculating elevation-dependent line scale factors for MGA, it has a tab for calculating them on the ACT Standard Grid.
Distance Reduction (ACT)
This is the same ICSM spreadsheet as found in the Geodetic Datum of Australia Technical Manual but with “ACT spheroid” details added, to enable one to perform calculations “on the surface” of that modified ellipsoid.
An additional tab has been added to enable one to “reconstruct” a slope distance that emulates a field-observed distance that has been corrected for ambient weather conditions. In effect, this is the reverse of the previous operation.
Distance reduction (ACT) spreadsheet (67.0 KB)
Rigorous Formulae between Ellipsoid and Grid
This spreadsheet allows for the computation, by Redfearn’s Formulae, of easting, northing, grid convergence and point scale factor from latitude and longitude, and the converse, viz. latitude, longitude, grid convergence and point scale factor from easting and northing.
It is identical to the ICSM spreadsheet, but with additional information to allow calculations between the ACT Standard Grid Co-ordinates (SGC) and AGD66.
Formulae on the Grid
This spreadsheet essentially allows you to radiate via grid bearing and distance from a known mark to generate co-ordinates for another, or to calculate a join between them, with geodetic corrections and terrain differences accounted for.
Although based on that given in the GDA Technical manual, this spreadsheet has been optimised for the ACT situation (610 metres has been added to the ANS semi-major axis length). Detailed explanatory notes are given in the "Parameters and Notes" tab.
Formulae on the grid spreadsheet (36.3 KB)
Formulae on the Ellipsoid
This is the same as the ICSM spreadsheet, but with the ACT Ellipsoid’s parameters added (a=6,378770m, f=1/298.25: Note that 610 metres has been added to the ANS semi-major axis length) to enable calculation of latitude, longitude and reverse azimuth from a mark and given the azimuth and spheroidal distance. Conversely, given the latitude and longitude of two marks, it calculates the spheroidal distance and forward and reverse azimuths between them. The formulae are those of Vincenty.
Formulae on the ellipsoid spreadsheet (107.5 KB)