Projection of a large spherical surface on to a plane [SEC=UNCLASSIFIED]
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? cheers, Paul
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> _______________________________________ [[alternative HTML version deleted]] _______________________________________________ R-sig-Geo mailing list R-sig-Geo at stat.math.ethz.ch https://stat.ethz.ch/mailman/listinfo/r-sig-geo
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 http://intamap.geo.uu.nl/~paul