[R-sig-Geo] Projection of a large spherical surface on to a plane [SEC=UNCLASSIFIED]

Paul Hiemstra p.hiemstra at geo.uu.nl
Tue Apr 28 11:37:17 CEST 2009

Hi Jin Li,

I seem to remember that gstat can deal with Great circle distances, but 
I could be wrong as I have never used them before. You say that a 
certain projection does not produce satisfactory results, how have you 
defined satisfactory?


Jin.Li at ga.gov.au wrote:
> Dear all,
> We are going to interpolate biophysical variables into continuous surface data using point samples in Australian EEZ that covers an area of 10 utm zones and ca. 44 degrees in terms of latitude. Our data is in lat and long (i.e., WGS84). We intend to apply kriging methods to such a big area. Of course, we can divide the whole EEZ into some subregions and actually we are going to divide it into some subregions based on a number of factors, but these sub-regions are still quite large and can cover 2 to 3 utms and 7-15 degrees in terms of latitude. Obviously it is not quite appropriate to treat a spherical surface as a plane. Given that kriging can not handle a spherical surface (hope this assumption is still valid), perhaps an alternative is project such spherical surface on to a plane. We have tried some equal distance projections to convert our data for Australian EEZ, but it seems that none of them can produce satisfactory projections, although sinusoidal gave slightly bette!
>  r results in comparison with utm projection. Any suggestions? Thanks in advance.
> Cheers,
> Jin
> _______________________________________
> Jin Li, PhD
> Spatial Modeller/Computational Statistician
> Marine & Coastal Environment
> Geoscience Australia
> GPO Box 378, Canberra, ACT 2601, Australia
> Ph: 61 (02) 6249 9899; email: jin.li at ga.gov.au<mailto:jin.li at ga.gov.au>
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Drs. Paul Hiemstra
Department of Physical Geography
Faculty of Geosciences
University of Utrecht
Heidelberglaan 2
P.O. Box 80.115
3508 TC Utrecht
Phone:  +3130 274 3113 Mon-Tue
Phone:  +3130 253 5773 Wed-Fri

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