Projection File

This is a data file which contains the parameters for all the allowable projections which will be handled by the program.

Two map projection files are supplied with GeoSurvey/GeoCadastre they are:
  1. MapProjections_Aust.csv - contains all commonly used Australian projections
  2. MapProjections_USA - Mainly USA related projections, but alsocontains other Northern Hemisphere projections.
CSV File Format
The file is a Comma Separated value (CSV) file and it contains one projection definition per line
with the parameters separated by commas.
The first few line consists of headings for the columns.
Any line that strats with a '!' character is ignored

You can edit the file with Excel or any text editor. See Text Editors.
Do not edit it with Microsoft Word!!!!

The file must be located in a directory with all the other string and symbol definition files. the location is defined in File/Settings/Program Settings/Reference Files...

Column Name Contents
1 - A Group The Group number allows grouping of datums for the same region, e.g. for Australia AGD was used prior to 2000 and GDA since then. If these datums have the same group number, it is assumed that there is a way to transform data from one to the other. In the USA the NAD27, NAD83 and NAD83HARN would all be in the same group.
2 - B Datum Name The name of the datum ‘GDA’, ‘NAD27’
3 - C Radius Radius of the earth
4 - D Earth Flattening Ratio difference between the major and minor earth radii
5 - E Projection Type Mercator or Lambert
6 - F Projection Name Name of the projection ‘UTM Zone 56’
7 - G Origin Latitude Latitude of the projection origin
8 - H Origin Longitude Longitude of the projection origin
9 - I Origin Easting Easting at the projection origin
10 - J Origin Northing Northing at the projection origin
11 - K Central Scale Factor The scale factor at the origin
12 - L Units Name Units: Metres, Feet or ‘US Survey Feet’
13 - M Units Factor to convert units to metres
14 - N Standard Parallel1 Reference parallel for Lambert Projection
15 - O Standard Parallel2 Reference parallel for Lambert Projection
16 - P Alternate Name Another name for the projection. This can be printed on GeoSurvey sheet title blocks as '%proj_code%'. See Plan Forms
17 - Q Comment Projection Description. This can be printed on GeoSurvey sheet title blocks as '%proj_descr%'. See Plan Forms
18 - R Source name of the Authority that created the Datum. This can be printed on GeoSurvey sheet title blocks as '%proj_source%'. See Plan Forms
19 - S Hemisphere 'North' or 'South' - If 'South', positive latitudes are in the Southern hemisphere. This saves you having to enter negative latitude all the time. If left blank this will default to 'South'.

Entries with the same group number - the user can transform data between the datums.

Entries with the same datum name - the user can transform data between the projectsions (subject to restriction on longitude).

For an explanation of Datums History, click here.