make_EPSG chile
On 28/01/13 11:48, Roger Bivand wrote:
On Mon, 28 Jan 2013, Mauricio Zambrano-Bigiarini wrote:
On 27/01/13 22:09, Orietta Nicolis wrote:
Dear R users, I'm trying to run the following example with data of Chile, but I didn't find a EPSG code for this country which could be used in R.
Hi Orietta, AFAIK, in Chile there are two main local projections: PSAD56 / UTM zone 18S, and PSAD56 / UTM zone 19S
But:
EPSG <- make_EPSG()
EPSG[grep("Chile", EPSG$note), 1:2]
code note 450 5360 # SIRGAS-Chile 2697 5361 # SIRGAS-Chile / UTM zone 19S 2698 5362 # SIRGAS-Chile / UTM zone 18S
I do not get those values:
library(rgdal)
Loading required package: sp
rgdal: version: 0.8-4, (SVN revision 431)
Geospatial Data Abstraction Library extensions to R successfully loaded
Loaded GDAL runtime: GDAL 1.8.1, released 2011/07/09
Path to GDAL shared files: /usr/share/gdal
GDAL does not use iconv for recoding strings.
Loaded PROJ.4 runtime: Rel. 4.7.1, 23 September 2009, [PJ_VERSION: 470]
Path to PROJ.4 shared files: (autodetected)
EPSG <- make_EPSG()
EPSG[grep("Chile", EPSG$note), 1:2]
[1] code note
<0 rows> (or 0-length row.names)
which is very likely due to the fact I'm using PROJ4 4.7.1 :(
all of which are WGS84 - do we know whether the +ellps in Orietta's data is GRS80 or your earlier intl?
She didn't mention it. I was working in Chile up to 2006, and at that time most of the cartography I saw from public institutions (related to water) used intl as ellipsoid. However, last December I realized the cartography (related to water) used WGS84.
With PROJ.4 4.8.0, we get a later EPSG too, with:
CRS("+init=epsg:24879")
CRS arguments: +init=epsg:24879 +proj=utm +zone=19 +south +ellps=intl +towgs84=-288,175,-376,0,0,0,0 +units=m +no_defs
Thank you very much for this info. I'll try to update my PROJ4.
which can be transformed to WGS84.
I recently used that projection. Then, when I transformed some features to WGS84 for visualizing in Google Earth, all of them were in close agreement with GE. Mauricio
Roger
which are used depending on the latitude you are working on.
For PSAD56_Z19S, you may try:
library(sp)
psad56.p4s <- CRS("+proj=utm +zone=19 +south +ellps=intl +units=m
+no_defs")
which is equivalent to use EPSG:24879
if you need higher precision, you may need to add the '+towgs84'
argument to 'psad56.p4s'
Saludos,
Mauricio
PS,
I'm happy to know there are people in Chile using R !