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Map projections - converting latitude/longitude to eastings and northings

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Map projections - converting latitude/longitude to eastings and northings

ssefick
I am trying to set up a Grass project and need to set up the region so
that I can view the map.  I can look at a map and find the lat/lon,
but the map projection is in UTM NAD38 WGS84 and I need to set the
eastings and northings.  Is there a package that will help me
calculate this in R.
thanks

--
Stephen Sefick

Let's not spend our time and resources thinking about things that are
so little or so large that all they really do for us is puff us up and
make us feel like gods.  We are mammals, and have not exhausted the
annoying little problems of being mammals.

                                                                -K. Mullis

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Re: Map projections - converting latitude/longitude to eastings and northings

Roger Bivand
Wouldn't grass-users, or maybe R-sig-geo be a more appropriate list? Given points in geographical coordinates, use project() or spTransform() in rgdal. The former will not do datum transformation, the latter will. NAD83 is a US datum specification based on WGS84, UTM is a projection but is useless without the zone number. If you can find the datum of your input data:

in_crs <- CRS("+proj=longlat +datum=<whatever>")
out_crs <- CRS("+proj=utm +zone=<#> +datum=NAD83 +ellps=WGS84")
utm_bbox <- bbox(spTransform(SpatialPoints(ll_crds, proj4string=in_crs), out_crs)

will get from one matrix of coordinates to the other. Note that for obvious reasons a rectangle on one side will only rarely be a rectangle on the other, so I've just taken a bounding box.

Roger Bivand

stephen sefick wrote
I am trying to set up a Grass project and need to set up the region so
that I can view the map.  I can look at a map and find the lat/lon,
but the map projection is in UTM NAD38 WGS84 and I need to set the
eastings and northings.  Is there a package that will help me
calculate this in R.
thanks

--
Stephen Sefick

Roger Bivand
Department of Economics
NHH Norwegian School of Economics
Helleveien 30
N-5045 Bergen, Norway
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Re: Map projections - converting latitude/longitude to eastings and northings

ssefick
Thank you for your reply.  Your suggestion for sending this to another
list is probably the right one.  I have just had so much wonderful
help on this one I thought I would try this one first.  I am very new
to GIS and have a couple of years of experience with R.  I will
probably join the sig-geo group to try and leverage my R knowledge
with GIS.  Thank you agian for your reply.

Stephen Sefick

On Thu, Jul 2, 2009 at 5:48 AM, Roger Bivand<[hidden email]> wrote:

>
> Wouldn't grass-users, or maybe R-sig-geo be a more appropriate list? Given
> points in geographical coordinates, use project() or spTransform() in rgdal.
> The former will not do datum transformation, the latter will. NAD83 is a US
> datum specification based on WGS84, UTM is a projection but is useless
> without the zone number. If you can find the datum of your input data:
>
> in_crs <- CRS("+proj=longlat +datum=<whatever>")
> out_crs <- CRS("+proj=utm +zone=<#> +datum=NAD83 +ellps=WGS84")
> utm_bbox <- bbox(spTransform(SpatialPoints(ll_crds, proj4string=in_crs),
> out_crs)
>
> will get from one matrix of coordinates to the other. Note that for obvious
> reasons a rectangle on one side will only rarely be a rectangle on the
> other, so I've just taken a bounding box.
>
> Roger Bivand
>
>
> stephen sefick wrote:
>>
>> I am trying to set up a Grass project and need to set up the region so
>> that I can view the map.  I can look at a map and find the lat/lon,
>> but the map projection is in UTM NAD38 WGS84 and I need to set the
>> eastings and northings.  Is there a package that will help me
>> calculate this in R.
>> thanks
>>
>> --
>> Stephen Sefick
>>
>>
>>
>>
>
> --
> View this message in context: http://www.nabble.com/Map-projections---converting-latitude-longitude-to-eastings-and-northings-tp24293706p24304700.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> [hidden email] mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>



--
Stephen Sefick

Let's not spend our time and resources thinking about things that are
so little or so large that all they really do for us is puff us up and
make us feel like gods.  We are mammals, and have not exhausted the
annoying little problems of being mammals.

                                                                -K. Mullis

______________________________________________
[hidden email] mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
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