[R-sig-Geo] help with args to CRS(), spTransform

[Michael Denslow]

Hi Roger,

>> Dear List,
>>
>> I am attending to transform a set of points that are originally in
>> latitude longitude (unprojected) to a Lambert Conformal Conic
>> projection.
>> I am a bit confused about the arguments to CRS and would appreciate any
>> help.
>
> Use one of the EPSG references, www.spatialreference.org, or the built in
> one:

Great to know about this site.

>
> library(rgdal)
> EPSG <- make_EPSG()
> EPSG[grep("North Carolina", EPSG$note),]
>
> The second one looks promising, so try:
>
> CRS("+init=epsg:3358")
>
> checking on:
>
> http://www.spatialreference.org/ref/epsg/3358/
>
> Hope this helps,


Fantastic, just what I was looking for.

Thank you again,

Michael

>
> Roger
>
>>
>> I have an old file that contains point distances that were measured
>> with the following projection information. This is from ArcMap which I
>> no longer use. I need to use this old file to compare with my new
>> distances.
>>
>> Projected Coordinate System: NAD_1983_StatePlane_North_Carolina_FIPS_3200
>> Projection: Lambert_Conformal_Conic
>> False_Easting: 609601.22000000
>> False_Northing: 0.00000000
>> Central_Meridian: -79.00000000
>> Standard_Parallel_1: 34.33333333
>> Standard_Parallel_2: 36.16666667
>> Latitude_Of_Origin: 33.75000000
>> Linear Unit: Meter
>>
>> Geographic Coordinate System: GCS_North_American_1983
>> Datum: D_North_American_1983
>> Prime Meridian: Greenwich
>> Angular Unit: Degree
>>
>> I would like the new point distance measurements that I am doing in
>> SPATSTAT to be comparable to the old ones that used the projection
>> above (in meters?).
>>
>> Here is what I have attempted...
>>
>> library(sp)
>> library(rgdal)
>> # dput(herb.sp) I hope this works I have never used dput() before!
>>
>> new("SpatialPoints"
>>   , coords = structure(c(-81.6809, -78.9455, -77.879, -83.1031, -78.6634,
>> -79.057, 36.2147, 35.9982, 34.227, 35.2571, 35.7853, 35.9097), .Dim =
>> c(6L,
>> 2L), .Dimnames = list(NULL, c("coords.x1", "coords.x2")))
>>   , bbox = structure(c(-83.1031, 34.227, -77.879, 36.2147), .Dim = c(2L,
>> 2L), .Dimnames = list(NULL, c("min", "max")))
>>   , proj4string = new("CRS"
>>   , projargs = " +proj=longlat +datum=WGS84 +ellps=WGS84 +towgs84=0,0,0"
>> )
>> )
>>
>> herb.lcc <- spTransform(herb.sp,CRS("+proj=lcc"))
>>
>>
>> I am not sure that this contains all of the arguments needed. I tried
>> looking at the PROG.4 manual here:
>> ftp://ftp.remotesensing.org/proj/OF90-284.pdf , but I am still unclear
>> how to proceed.
>>
>> Any help would be most appreciated!
>> Thanks again,
>> Michael
>>
>>
>>
>>
>
> --
> Roger Bivand
> Economic Geography Section, Department of Economics, Norwegian School of
> Economics and Business Administration, Helleveien 30, N-5045 Bergen,
> Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
> e-mail: Roger.Bivand at nhh.no
>
>



-- 
Michael Denslow

Graduate Student & Adjunct Instructor
I.W. Carpenter Jr. Herbarium [BOON]
Department of Biology
Appalachian State University
Boone, North Carolina U.S.A.
-- AND --
Communications Manager
Southeast Regional Network of Expertise and Collections
sernec.org

36.214177, -81.681480 +/- 3103 meters