Hello again!  Happy New Year!

Here is the solution for this particular situation.  Note:  thanks to many people for the help.  Anyhow, I started with looking at page 28 in the gstat vignette for krigeST.  If you work through that, you obtain an object called DE_kriged, which is an STFDF.

I copied some code from the following website:

(https://r-forge.r-project.org/scm/viewvc.php/pkg/R/coerce.R?view=markup&root=spacetime
<https://r-forge.r-project.org/scm/viewvc.php/pkg/R/coerce.R?view=markup&root=spacetime&pathrev=25>)

to get the as.STIDF.STFDF lines:



# STFDF -> STIDF
as.STIDF.STFDF = function(from) {
        as(as(from, "STSDF"), "STIDF")
}
setAs("STFDF", "STIDF", as.STIDF.STFDF)


Now:

>  DE1 <- as.STIDF.STFDF(DE_kriged)

DE1 is an STIDF object, which is good, but the @sp section is a Spatial Pixels object.

Next I copied over the function kml_layer.STIDF to new_STIDF.R and added the following section (see the note)

new.STIDF <-
function (obj, dtime = "", ...)
{
    if (all(dtime == 0)) {
        TimeSpan.begin = format(time(obj@time), "%Y-%m-%dT%H:%M:%SZ")
        TimeSpan.end = TimeSpan.begin
    }
    else {
        if (length(obj@time) > 1 & !nzchar(dtime)) {
        print(obj@time)
            period <- periodicity(obj@time)
            dtime <- period$frequency
        }
        TimeSpan.begin <- format(as.POSIXct(unclass(as.POSIXct(time(obj@time))) -
            dtime/2, origin = "1970-01-01"), "%Y-%m-%dT%H:%M:%SZ")
        TimeSpan.end <- format(as.POSIXct(unclass(as.POSIXct(time(obj@time))) +
            dtime/2, origin = "1970-01-01"), "%Y-%m-%dT%H:%M:%SZ")
    }
    if (class(obj@sp) == "SpatialPoints" | class(obj@sp) == "SpatialPointsDataFrame") {
        sp <- SpatialPointsDataFrame(obj@sp, obj@data)
        kml_layer.SpatialPoints(obj = sp, TimeSpan.begin = TimeSpan.begin,
            TimeSpan.end = TimeSpan.end, ...)
    }
    else {
        if (class(obj@sp) == "SpatialPolygons" | class(obj@sp) ==
            "SpatialPolygonsDataFrame") {
            sp <- SpatialPolygonsDataFrame(obj@sp, obj@data)
            kml_layer.SpatialPolygons(obj = sp, TimeSpan.begin = TimeSpan.begin,
                TimeSpan.end = TimeSpan.end, ...)
        }
        else {
            if (class(obj@sp) == "SpatialLines" | class(obj@sp) ==
                "SpatialLinesDataFrame") {
                sp <- SpatialLinesDataFrame(obj@sp, obj@data)
                kml_layer.SpatialLines(obj = sp, TimeSpan.begin = TimeSpan.begin,
                  TimeSpan.end = TimeSpan.end, ...)
            }

###########################################################
#  New for Spatial Pixels                                 #
##########################################################
        else {
            if (class(obj@sp) == "SpatialPixels" | class(obj@sp) ==
                "SpatialPixelsDataFrame") {
                sp <- SpatialPixelsDataFrame(obj@sp, obj@data)
                kml_layer.SpatialPoints(obj = sp, TimeSpan.begin = TimeSpan.begin,
                  TimeSpan.end = TimeSpan.end, ...)
            }



            else {
                stop("The STIDF object does not extend SpatialPoints*, SpatialLines* or SpatialPolygons*")
            }
        }
    }
}
}

Finally, I ran this:
> library(plotKML)
plotKML version 0.4-0 (2013-11-15)
URL: http://plotkml.r-forge.r-project.org/
Warning message:
replacing previous import by ‘zoo::as.zoo’ when loading ‘gstat’
> library(gstat)
Loading required package: sp
> kml_open("stuff2.kml")
KML file opened for writing...
> new.STIDF(DE1,dtime=24*3600,colour=var1.pred)
Parsing to KML...
> kml_close("stuff2.kml")
Closing  stuff2.kml
>

All is well.  Google Earth lets you run the kml file and show the time change, as it should.

Hope this might help someone!

Thanks,
Erin







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