[R-sig-Geo] [OT] Coordinates and pojection problems

[Julien Barnier]

Hi,

I'm sorry to post a rather off-topic question here, but as a new sp
user and total novice in coordinates and projections questions, I'm
facing a problem you may help me to solve. Please ignore this post if
it is too much noise.

I've got two map files (a MapInfo file and an ESRI shapefile) from two
different sources but which represent objects from the same french
region (one represent the cities, the other rivers and water
surfaces). 

The problem is that when imported into R and plotted together, they
doesn't appear in the same place.  They seem to have the same
«longitude», but the «latitude» is different. If I plot them, the
first map ranges in the Y axis from 70,000 to 100,000 and the second
one from 2,060,000 to 2,140,000. The ranges along the x axis seem to
be the same, though.

Here is the output of ogrinfo on the two files :

,----
| $ ogrinfo -so 69_iris.mid 69_iris
| Had to open data source read-only.
| INFO: Open of `69_iris.mid'
|       using driver `MapInfo File' successful.
| 
| Layer name: 69_iris
| Geometry: Unknown (any)
| Feature Count: 774
| Extent: (747910.000000, 2053380.000000) - (819740.000000,
| 2147622.300000)
| Layer SRS WKT:
| PROJCS[«unnamed»,
|     GEOGCS[«unnamed»,
|         DATUM[«MIF 9999,6,-168,-60,320,0,0,0,0,0»,
|             SPHEROID[«Clarke 1880»,6378249.145,293.465],
|             TOWGS84[-168,-60,320,-0,-0,-0,0]],
|         PRIMEM[«non-Greenwich»,0],
|         UNIT[«degree»,0.0174532925199433]],
|     PROJECTION[«Lambert_Conformal_Conic_2SP»],
|     PARAMETER[«standard_parallel_1»,45.90287723937],
|     PARAMETER[«standard_parallel_2»,47.69712276063],
|     PARAMETER[«latitude_of_origin»,46.8],
|     PARAMETER[«central_meridian»,2.337229104484],
|     PARAMETER[«false_easting»,600000],
|     PARAMETER[«false_northing»,2200000],
|     UNIT[«Meter»,1]]
| DepCom: String (5.0)
| Nom_Com: String (40.0)
| Iris: String (4.0)
| DComIris: String (9.0)
| Nom_Iris: String (43.0)
| Typ_Iris: String (1.0)
| Indic: String (1.0)
| Origine: String (1.0)
`----

,----
| $ ogrinfo -so Decoupage_Administratif/SURFDEAU.shp SURFDEAU
| INFO: Open of `Decoupage_Administratif/SURFDEAU.shp'
|       using driver `ESRI Shapefile' successful.
| 
| Layer name: SURFDEAU
| Geometry: Polygon
| Feature Count: 168
| Extent: (785619.190000, 68133.620000) - (818193.410000, 107443.340000)
| Layer SRS WKT:
| (unknown)
| NUMOBJ: String (11.0)
`----

I've tried to play with some parameters in readShapePoly and
spTransform, but without success.

Any help would be greatly appreciated.

Thanks in advance,
-- 
Julien Barnier
Groupe de recherche sur la socialisation
ENS-LSH - Lyon, France