Global Analysis Projections – Choosing Projections for Area and Distance

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I am looking for a projection (or a set of projections) that decently preserve distances so that I can buffer every country in the world and have a similar level of minimal distortion for each.

I then need a projection (or set of projections) to compute the areas of these buffers so that each country in the world's buffer area can be compared with any other country's buffer area.

Eventually I will need to do a bunch of overlays onto these areas to chop up and assign other statistics based on proportion of overlap and such. All of these resulting stats need to be comparable with every other country in the world. At this stage in the game, I am thinking that must be done in an equal-area projection(s) as well.

It is the first time I am operating at a scale smaller than local or regional, and the results will have to be defensible and open to peer-review. I am assuming it is improper to do all of these things in lat/lng, but then when I think about the logic of why, I confuse myself!

I appreciate any info, opinions, reflections on similar experiences, etc anyone has about this!

Best Answer

The latest PostGIS has a "Geography" data type which does calculations on Lat/Lon WGS84 spatial reference system data, and returns the distance or area results in meters/sq. meters based on the WGS84 ellipsoid. So you could bring your country data into PostGIS in WGS84 Lat/Lon, using Geography instead of Geometry and then create the buffers, and do the area calculations with the built in functions.

See: ST_Buffers ST_Area and PostGIS Geography

-- Micha

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