from long/lat to UTM
On 10-Mar-05 Sander Oom wrote:
Hi Yyan, The proj4R package by Roger Bivand will allow you to project data in many ways and directions. http://spatial.nhh.no/R/Devel/proj4R-pkg.pdf It uses the proj libraries from: http://www.remotesensing.org/proj/ Not sure where you would derive the time zone! Good luck, Sander.
While there is a longitude-based "nominal" time-zone structure (0deg E is the centre of Zone 0 which extends for 7.5deg either side; successive time-zones move round by 15deg), this does not apply cleanly to the time-shifts adopted in different places for local time. A World map of regions with different local-time offsets is a crazy patchwork, with all sorts of contradictory looking regions. For instance, the "-0700" region of the USA extends from approx -0830 to approx -0620, covering over 2 hours, and parts of "-0800" touch the -0700 line and are more than 0100 East of parts of "-0700". Even worse can be found over the Indian/Central Asian and Malaysian parts of the world, where time-shifts of 30 miniutes are also frequent (and, according to my Atlas, one country, Nepal, has "5&2/3" i.e. +0540!). As Sander says, "Not sure where you would derive the time zone!". Unless you can refer a (long,lat) position to a look-up table, you can't predict what the zone will be to less the 1 hour (except of course for the "nominal" time-zones by 15deg sectors). I've never encountered a "digital" version of such a table (my Atlas must be based on one, though). Best wishes, Ted.
yyan liu wrote:
Hi: Is there any function in R which can convert the long/lat to UTM(Universal Transverse Mercator)? There are quite a few converters on Internet. However, the interface is designed as input->output which I can not convert lots of locations at the same time. Another question is whether there is a function in R which can tell the time zone from the location's lat/long? Thank you! liu
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-- -------------------------------------------- Dr. Sander P. Oom Animal, Plant and Environmental Sciences, University of the Witwatersrand Private Bag 3, Wits 2050, South Africa Tel (work) +27 (0)11 717 64 04 Tel (home) +27 (0)18 297 44 51 Fax +27 (0)18 299 24 64 Email sander at oomvanlieshout.net Web www.oomvanlieshout.net/sander
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