add result of image.plot layer on geographic map (bing map)

Question

I have a 2D footprint result for an eddy-covariance system on a 1100*1100 square meter, with the domain of

    domain = c(-100,1000,-100, 1000)

the cell size of the domain (each grid) is 2 meters with the origin (0,0) accordingly on this location:

    Lon = -97.191391  #longtitude
    Lat = 36.055935   #latitude

An example data (9.01 Mb) is attached here. FFP.rds

then I can plot a Bing map on my site as this:

   library(OpenStreetMap)
   library(rgdal)              
   map <- openmap(c(36.05778,-97.19250), c(36.05444,-97.18861),type='bing')
   plot(map)

and I use image.plot() from package "fields" to plot the footprint with these following codes:

  library(fields)
  str(FFP$fclim_2d)
  image.plot(FFP$x_2d[1,],FFP$y_2d[,1],FFP$fclim_2d)

But I am wondering how to scale each grid of my footprint result to Bing map (or google map).

Any suggestions would be greatly appreciated.