1

I am calculating areas of polygons and distances between points in a small park in South Australia (~ 139.4 longitude, -34.3 latitude). All of these points are currently in GCS WGS 1984, and the polygons are all less than 1 square kilometer.

I am trying to determine the best projected coordinate system for these calculations, and I have come upon multiple options. I read that, for small local areas of the Australian continent, MGA is an ideal projection, so I am considering using GDA 1994 MGA Zone 54. However, I've also read that for area calculations, it is best to use an equal area projection, so I have also considered using GDA 1994 Australia Albers.

2

My advice would be use both and then compare the results. Depending on the accuracy you require, you might find that the results are comparable. That is, if you round up to the nearest metre squared, the number might be the same.

GDA 1994 Australia Albers is great if you are dealing with areas that cover multiple zones (i.e. measuring a polygon area that is half in zone 54 and half in zone 53). But if it's a small park and the whole polygon falls within zone 54 then I would stick with GDA 1994 MGA Zone 54.

This is the description of the scope of GDA 1994 Australia Albers from:spatial reference org website

Scope: Australia-wide geoscience and statistical mapping.

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