[R-sig-Geo] Transforming from WGS84 to NAD83 Stateplane Alaska zone 1

[Barry Rowlingson]

On Thu, Jul 19, 2012 at 3:11 AM, Gregovich, Dave P (DFG)
<dave.gregovich at alaska.gov> wrote:
> Hello,
>
> I apologize for reposting, but am still confounded after spending more time
> with the following problem, despite some help from the group.
>
>
>
> I am attempting to learn GIS in R. I have worked with ArcGIS a lot, and know
> that my data is projecting correctly in that environment relative to other
> trusted data.  When I import a text file of animal locations into ArcGIS,
> then define the projection as WGS84, then transform to NAD83, I can obtain
> proj4strings from the resulting shapefiles to use as follows:
>

 Yeah there's a constant shift between the R coordinates and the ESRI
coordinates:

 > coordinates(bear_R_nad83)-coordinates(bear_ArcGIS_nad83)
      coords.x1 coords.x2
 [1,]   4181322  -5575097
 [2,]   4181322  -5575097
 [3,]   4181322  -5575097

 - a workaround would just be to add this offset to your coordinates....

 I've tried to figure out where this is coming from but with no
success. I've not had any problems with coordinates as long as I stick
to EPSG-defined coordinate systems. I don't have a copy of ArcGis to
hand, but I recall it has all sorts of other systems in it....

Barry