Dave,

What I would do is project the data in ArcGIS, and and then read them into
R and use proj4string to get the projection from that object. Then use that
proj4string to project, in R, the lon/lat data and see if they now match
up. I just did that and I think you espgs code in incorrect. I would
generally avoid these opaque codes, certainly when sending a question to
the list. For you epsg code, I get:

> proj4string(bear414_nad83)
[1] " +init=epsg:26931 +proj=omerc +lat_0=57 +lonc=-133.6666666666667
+alpha=323.1301023611111 +k=0.9999 +x_0=5000000 +y_0=-5000000 +ellps=GRS80
+datum=NAD83 +units=m +no_defs +towgs84=0,0,0"
>

For ArcGIS I get something else (the value of alpha):

[1] "+proj=omerc +lat_0=57 +lonc=-133.6666666666667
+alpha=-36.86989764583333 +k=0.9999 +x_0=5000000 +y_0=-5000000 +datum=NAD83
+units=m +no_defs +ellps=GRS80 +towgs84=0,0,0"
>

Robert


On Thu, Jul 5, 2012 at 11:59 AM, Gregovich, Dave P (DFG) <
dave.gregovich@alaska.gov> wrote:

> Hello, ****
>
> ** **
>
> I am new to R-sig-geo, thanks for your patience.****
>
> ** **
>
> I am trying to bring GPS animal collar data into R and correctly project
> it to NAD83 Alaska Stateplane zone 1 (epsg:26931 should be the correct
> proj4 code). In leiu of any other way to verify if my projection is
> working, I am comparing it to results in ArcGIS (this is the first time I
> have tried to bring GIS data into R). The problem I am having is that the
> ArcGIS and R (via RGDAL and sp) processes result in vastly different
> projected coordinates. Below is the R code I am using:****
>
> ** **
>
> #wgs 84 definition****
>
> wgs84<-"+init=epsg:4326"****
>
> #NAD 83 stateplane Alaska zone 1 definition****
>
> ak.sp.z1<-"+init=epsg:26931"****
>
> ** **
>
> ** **
>
> txt.loc<-"C:/bear414.txt"****
>
> bear414<-read.table(txt.loc,header=T,sep=",",stringsAsFactors=F)****
>
> coordinates(bear414)<-c("Long_","Latitude")****
>
> proj4string(bear414)<-CRS(wgs84)****
>
> bear414_nad83<-spTransform(bear414,CRS(ak.sp.z1))****
>
> writeOGR(obj=bear414_nad83,dsn="C:/dave/temp/rgis",layer="test414",****
>
>
> driver=as.character(ogrDrivers()[7,1]),overwrite_layer=TRUE)****
>
> ** **
>
> I realize that this is not an ArcGIS-related list, but in case it helps,
> the process I use in ArcGIS is essentially:****
>
> Display xy-coordinates, export to WGS84 shapefile, and project to new
> NAD83 Alaska stateplane zone 1 shapefile. Also, when I use proj4string() on
> NAD83 Alaska stateplane zone 1 shapefiles that are from a published source
> (eg. the Southeast Alaska GIS library), the string is identical to that
> referenced by epsg:26931.****
>
> ** **
>
> The rough difference (clicking on eye-balled centroid) between the ArcGIS
> and R results I am getting are: ArcGIS--    x: 726509 y: 801767, R--   x:
> 4912400 y: -4784000****
>
> ** **
>
> Thanks so much for your time. I have spent almost two entire days on this
> problem and look forward to eventually overcoming this hurdle!****
>
> ** **
>
> Dave****
>
> ** **
>
> system: windows 7 x64****
>
> windows version: build 7601, Service Pack 1****
>
> R version: 2.15.1****
>
> ** **
>
> ** **
>
> __________________________________****
>
> Dave Gregovich****
>
> Research Analyst****
>
> Alaska Department of Fish and Game****
>
> Wildlife Conservation Division****
>
> Douglas, AK 99821****
>
> (907) 465-4291****
>
> dave.gregovich@alaska.gov****
>
> __________________________________****
>
> ** **
>
> _______________________________________________
> R-sig-Geo mailing list
> R-sig-Geo@r-project.org
> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>
>

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