[R-sig-Geo] CRS: list of datum?

[Agustin Lobo]

Casper,

Thanks, this is very useful, although does not solve my problem.
What I would need is to define:

proj4string(lakes) <- CRS("+proj=utm +zone=35 +datum=ED87
+towgs84=-82.981,-99.719,-110.709,-0.5076,0.1503,0.3898")

according to
http://www.asprs.org/resources/grids/10-99-norway.pdf

My question is why +datum=WGS84 works but +datum=ED87 or +datum=ED50
do not work?

Using A <- make_EPSG() I've been able to find:

> A$note[grep("ED",A$note)]
> A[160,]
    code   note                               prj4
160 4231 # ED87 +proj=longlat +ellps=intl +no_defs

but this is a lonlat projection, what I need is a UTM projection.

I've also found:

> A[2540,]
      code                  note
      prj4
2540 23035 # ED50 / UTM zone 35N +proj=utm +zone=35 +ellps=intl
+units=m +no_defs

and have used:

> proj4string(lakes) <-CRS(paste("+init=epsg:23035",
 "+towgs84=-82.981,-99.719,-110.709,-0.5076,0.1503,0.3898"))
> lakesll <- spTransform(lakes, CRS("+proj=longlat +datum=WGS84"))
> writeOGR(lakesll,dsn="Kolalakesll",layer="Kolalakesll",driver="ESRI Shapefile")

but lakesll is shifted if overlaid on an image with lonlat and WGS84
"projection" and
I suspect the reason is using ED50 instead of ED87.

Note1. lakes comes from:

library(StatDA)
library(maptools)
xy <- kola.background$lakes
names(xy) <- c("x", "y")
lakes <- map2SpatialLines(xy)
lakesdata <- data.frame(ID=1:131,lakename=rep("",131),stringsAsFactors=F)
row.names(lakesdata) <- 1:131
lakes <- SpatialLinesDataFrame(sl=lakes, data=lakesdata, match.ID = TRUE)

Note2: sessionInfo()
R version 2.11.1 (2010-05-31)
i486-pc-linux-gnu

locale:
 [1] LC_CTYPE=en_US.UTF-8          LC_NUMERIC=C
LC_TIME=en_US.UTF-8
 [4] LC_COLLATE=en_US.UTF-8        LC_MONETARY=en_US.UTF-8
LC_MESSAGES=en_US.UTF-8
 [7] LC_PAPER=en_US.UTF-8          LC_NAME=en_US.UTF-8
LC_ADDRESS=en_US.UTF-8
[10] LC_TELEPHONE=en_US.UTF-8      LC_MEASUREMENT=en_US.UTF-8
LC_IDENTIFICATION=en_US.UTF-8

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

other attached packages:
[1] rgdal_0.6-27 raster_1.1.2 sp_0.9-62    rkward_0.5.4

loaded via a namespace (and not attached):
[1] grid_2.11.1     lattice_0.19-11 tools_2.11.1

Thanks!
Agus

2010/10/11 caspar hallmann <caspar.hallmann at gmail.com>:
> HI Agus,
>
> see
> A=make_EPSG()
> A
>
> in rgdal
>
> Caspar
>
>
>
>
>
> On Sun, Oct 10, 2010 at 10:36 PM, Agustin Lobo <alobolistas at gmail.com> wrote:
>> HI!
>>
>> While
>>> CRS("+proj=utm +zone=32 +datum=WGS84")
>> CRS arguments:
>>  +proj=utm +zone=32 +datum=WGS84 +ellps=WGS84 +towgs84=0,0,0
>>
>> is correct, the same with ED50 is not:
>>
>>> CRS("+proj=utm +zone=32 +datum=ED50")
>> Error in CRS("+proj=utm +zone=32 +datum=ED50") :
>>  unknown elliptical parameter name
>>
>> Is there any way to get the list of available datum acronyms?
>>
>> Thanks
>>
>> Agus
>>
>> _______________________________________________
>> R-sig-Geo mailing list
>> R-sig-Geo at stat.math.ethz.ch
>> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>>
>
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