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I'm just getting started on a long-term project involving northern Delaware. Most of my distances will use great circle distances from the lat/lon, but for a few applications I'll wind up using standard distance functions (e.g. gDistance from rgeos). I'd like to pick an equidistant projection centered in this area (say, on Lat +39.7033053 Lon -075.6867863). The distances involved are small (about 15 mile radius), so it's not critical, but it would be nice to not be using a grossly inappropriate projection.

Can I take something like the USA Contiguous Equidistant Conic and re-center it on that point, or is there a better projection for small-area analysis? If the former, how do I do it and get a proj4string at the end?

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    For small areas, state plane is your best bet, and you don't need to sweat custom projection issues. – Vince Nov 27 '13 at 16:36
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    Just about any projection centered on your area will work beautifully for these distances, because most projections have at least one central point at which there is no scale distortion at all and the amount of distortion increases only slowly in the vicinity of that point. – whuber Nov 27 '13 at 17:30
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Delaware Stateplane, EPSG:2235 should work well for the whole state.

  • In conjunction with @Vince's comment, this seems like the best solution. Thanks! – Ari B. Friedman Nov 27 '13 at 16:39

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