Hi all,

I intend to use gDistance function in rgeos package to measure the distance
among a large number of polygons in a vector map.
Specifically, I measure distances to a maximum extent of about 1000 km in
various directions and at different latitudes.
My concern is whether the distance calculated is corrected for the
projection used (geodesic distance).
If not, is there any similar function which work on unprojected data
(latlong) and measure a correct geodesic distance?
Otherwise, which projection would better reduce the error?
Is any bias due the projection relevant at my scale (max 1000 km)? To what
extent?

Thank you for the help,


Luca Santini, PhD student
Global Mammal Assessment program

Department of Biology and Biotechnologies
Sapienza Università di Roma.
Zoology Building - Viale dell'Università 32,00185 Rome, Italy



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