Actually I believe for kml you must use geographic coordinates unprojected. WGS 84 Lat/Lon , EPSG:4326
And yes it's only so Google maps/earth knows what to do with it. If I could make head or tails of OGC specs I'm sure it says something about it in there. Alex On 05/29/2010 12:21 AM, Agustin Lobo wrote: > Excuses for the quite adjacent question, does anybody know if kml files > require > using the google spherical projection? > My understanding is that, in theory, you can use any projection, but, > in fact, you must use > google spherical to get a correct display in google maps > > Agus > > 2010/5/28 Wade Wall <wade.w...@gmail.com>: >> Thanks Dr. Bivand, >> >> I was able to import my kml file using your example. I opened up the >> kml file in a text editor to find out the layer name, but >> system(paste("ogrinfo", paste(td, "cities.kml", sep="/")), >> intern=TRUE) also works to find the name. >> >> As for modifying ogrinfo(), I will take a look and see if it is above >> my skill level or not. >> >> Wade >> >> On Fri, May 28, 2010 at 3:29 AM, Roger Bivand <roger.biv...@nhh.no> wrote: >>> On Thu, 27 May 2010, Wade Wall wrote: >>> >>>> I am not exactly sure what you mean by identify the correct layer >>>> name. Using R under Linux, this is what happens. >>>> >>>> I have a file in the current directory named ASMI_GA.kml >>>> >>>> library(rgdal) >>>> tmp<-readOGR(".", layer="ASMI_GA.kml") >>>> >>>> However, I get the following message. >>>> >>>> Error in ogrInfo(dsn = dsn, layer = layer, input_field_name_encoding = >>>> input_field_name_encoding) : >>>> Cannot open file >>> >>> That is what I said. Each driver has its own understanding of what the dsn= >>> and layer= arguments are, and your usage doesn't match what the driver is >>> expecting. The dsn= for the KML driver seems to be the file name (possibly >>> with its complete path), and the layer= is the string in the: >>> >>> <Document><Folder><name>cities</name> >>> >>> line (conditional on the writing software using a similar logic to OGR), >>> here in this example: >>> >>> library(rgdal) >>> cities <- readOGR(system.file("vectors", package = "rgdal")[1], "cities") >>> is.na(cities$POPULATION) <- cities$POPULATION == -99 >>> summary(cities$POPULATION) >>> td <- tempdir() >>> writeOGR(cities, paste(td, "cities.kml", sep="/"), "cities", driver="KML") >>> xx <- readOGR(paste(td, "cities.kml", sep="/"), "cities") >>> >>> How one discovers this name is not obvious, since the KML driver in OGR >>> needs it to access the file. One possibility is: >>> >>> system(paste("ogrinfo", paste(td, "cities.kml", sep="/")), intern=TRUE) >>> >>> which lists the layer name(s). Perhaps ogrInfo() could be revised to access >>> the dsn in the same way when not given a layer= argument to discover layer >>> names - anyone with lots of time on their hands like to help? >>> >>> Roger >>> >>> PS. ogrDrivers() lists the drivers seen by OGR as running in rgdal, but for >>> drivers with write but not read capability, it cannot distinguish. In that >>> case, you only find out if a read driver is present and has its external >>> dependencies properly satisfied by using it, I'm afraid. The example above >>> will show whether your rgdal/GDAL/Expat do work or not. >>> >>>> >>>> I have expat XML parser installed and gdal. This probably sounds >>>> rather stupid, but I am not sure what the following means in the link >>>> that Dr. Bivand provided: "KML reading is only available if GDAL/OGR >>>> is built with the Expat XML Parser, otherwise only KML writing will be >>>> supported." I installed both as debian packages (using get-apt). >>>> Should I install both from source code, Expat XML Parser first and >>>> then GDAL? >>>> >>>> Sorry if I seem dense here, but it is not real clear to me. Also, >>>> even though this may be beyond the scope of R-sig-geo, I think that >>>> other people are also struggling with this. >>>> >>>> Thanks for any help. >>>> >>>> Wade >>>> >>>> >>>> On Thu, May 27, 2010 at 2:15 PM, Roger Bivand <roger.biv...@nhh.no> wrote: >>>>> >>>>> On Thu, 27 May 2010, rick reeves wrote: >>>>> >>>>>> I do note that the example I provided does not demonstrate how to READ a >>>>>> KML >>>>>> file into R. But, SOON, I plan to modify the example to demonstrate >>>>>> reading of KMLs >>>>>> into some R-compatible format. >>>>> >>>>> readOGR() does read KML files, but you do have to identify the correct >>>>> layer >>>>> name - see: >>>>> >>>>> http://www.gdal.org/ogr/drv_kml.html >>>>> >>>>> Roger >>>>> >>>>>> >>>>>> RR >>>>>> >>>>>> On 5/27/2010 10:15 AM, Wade Wall wrote: >>>>>>> >>>>>>> Hi all, >>>>>>> >>>>>>> Does anyone have experience reading and writing KML files in R? I >>>>>>> have seen several threads that seem to suggest that it is difficult if >>>>>>> not impossible, but it is convenient to use KML files when working >>>>>>> with Google Earth and inconvenient to read and write shapefiles and >>>>>>> then convert to KML using other software. >>>>>>> >>>>>>> If anyone is able to read and write KML files, if they could provide a >>>>>>> description of how to do it, I am sure a lot of people would >>>>>>> appreciate it. I have tried to do so under both Windows and Linux to >>>>>>> no avail. The Windows approach looks more difficult, judging by the >>>>>>> readme file associated with rgdal. >>>>>>> >>>>>>> Thanks, >>>>>>> >>>>>>> Wade >>>>>>> >>>>>>> _______________________________________________ >>>>>>> R-sig-Geo mailing list >>>>>>> R-sig-Geo@stat.math.ethz.ch >>>>>>> https://stat.ethz.ch/mailman/listinfo/r-sig-geo >>>>>>> >>>>>>> >>>>>> >>>>>> >>>>>> >>>>> >>>>> -- >>>>> Roger Bivand >>>>> Economic Geography Section, Department of Economics, Norwegian School of >>>>> Economics and Business Administration, Helleveien 30, N-5045 Bergen, >>>>> Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43 >>>>> e-mail: roger.biv...@nhh.no >>>>> >>>>> >>>> >>> >>> -- >>> Roger Bivand >>> Economic Geography Section, Department of Economics, Norwegian School of >>> Economics and Business Administration, Helleveien 30, N-5045 Bergen, >>> Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43 >>> e-mail: roger.biv...@nhh.no >>> >> >> _______________________________________________ >> R-sig-Geo mailing list >> R-sig-Geo@stat.math.ethz.ch >> https://stat.ethz.ch/mailman/listinfo/r-sig-geo >> > > _______________________________________________ > R-sig-Geo mailing list > R-sig-Geo@stat.math.ethz.ch > https://stat.ethz.ch/mailman/listinfo/r-sig-geo _______________________________________________ R-sig-Geo mailing list R-sig-Geo@stat.math.ethz.ch https://stat.ethz.ch/mailman/listinfo/r-sig-geo