function (dataFrame = NULL, server = "google", zoom = 14) 
{
    dataFrameMissing = 0
    if (missing(dataFrame)) {
        print("No data frame declared.", quote = FALSE)
        print("Syntax is: getInfra(dataFrame, server, zoom)", 
            quote = FALSE)
        print("Exiting.", quote = FALSE)
        dataFrameMissing = 1
    }
    if (dataFrameMissing == 0) {
        if (missing(server)) {
            print("Server was not declared.  Options are 'google', 'bing' or 'open'.  Defaulting to google.", 
                quote = FALSE)
        }
        if (missing(zoom)) {
            print("Zoom was not declared.  Defaulting to 14.  For google, valid values are 0 (whole world) to 22 (street level); 1 to 19 for bing; 0 to 19 for open.", 
                quote = FALSE)
        }
    }
    serverFound = 0
    if (server == "google") {
        serverFound = 1
        lineCounter = 1
        googleFileSize <- NULL
        progressBar <- txtProgressBar(min = 0, max = length(dataFrame$lat), 
            style = 3)
        while (lineCounter < (length(dataFrame$lat) + 1)) {
            degLat = dataFrame$lat[lineCounter]
            degLng = dataFrame$lng[lineCounter]
            zValue = zoom
            mapSize = 2^zValue
            radLat = degLat * (pi/180)
            pixelY = 0.5 * (log((1 + sin(radLat))/(1 - sin(radLat))))
            pixelY = pixelY/(pi/(mapSize/2))
            pixelY = (mapSize/2) - pixelY
            pixelY = round(pixelY)
            pixelX = (mapSize/2) + (degLng * ((mapSize/2)/180))
            pixelX = round(pixelX)
            urlToGet = paste("http://mt0.google.com/vt/lyrs=m@0&hl=en&x=", 
                pixelX, "&y=", pixelY, "&z=", zValue, sep = "")
            download.file(url = urlToGet, destfile = "googleFileContents.txt", 
                quiet = TRUE, mode = "w", cacheOK = TRUE, extra = getOption("download.file.extra"))
            fileSize = file.info("googleFileContents.txt")["size"]$size
            googleFileSize = c(googleFileSize, fileSize)
            lineCounter = lineCounter + 1
            setTxtProgressBar(progressBar, lineCounter)
        }
        return(googleFileSize)
        file.remove("googleFileContents.txt")
        close(progressBar)
    }
    if (server == "bing") {
        serverFound = 1
        lineCounter = 1
        bingFileSize <- NULL
        progressBar <- txtProgressBar(min = 0, max = length(dataFrame$lat), 
            style = 3)
        while (lineCounter < (length(dataFrame$lat) + 1)) {
            inputLat = dataFrame$lat[lineCounter]
            inputLng = dataFrame$lng[lineCounter]
            minLat = -85.05112878
            maxLat = 85.05112878
            imageWidthAndHeight = bitwShiftL(256, zoom)
            if (inputLat < minLat) {
                inputLat = minLat
            }
            if (inputLat > maxLat) {
                inputLat = maxLat
            }
            firstX = (inputLng + 180)/360
            sinLat = sin(inputLat * pi/180)
            firstY = 0.5 - log((1 + sinLat)/(1 - sinLat))/(4 * 
                pi)
            pixelX = round(firstX * imageWidthAndHeight)
            pixelY = round(firstY * imageWidthAndHeight)
            tileX = pixelX/256
            tileY = pixelY/256
            quadKey = NULL
            for (i in zoom:1) {
                digit = 0
                mask = bitwShiftL(1, i - 1)
                if (bitwAnd(tileX, mask) != 0) {
                  digit = digit + 1
                }
                if (bitwAnd(tileY, mask) != 0) {
                  digit = digit + 2
                }
                quadKey = paste(quadKey, digit, sep = "")
            }
            urlToGet = paste("http://ak.dynamic.t0.tiles.virtualearth.net/comp/ch/", 
                quadKey, "?mkt=en-gb&it=G,VE,BX,L,LA", sep = "")
            download.file(url = urlToGet, destfile = "bingFileContents.txt", 
                quiet = TRUE, mode = "w", cacheOK = TRUE, extra = getOption("download.file.extra"))
            fileSize = file.info("bingFileContents.txt")["size"]$size
            bingFileSize = c(bingFileSize, fileSize)
            lineCounter = lineCounter + 1
            setTxtProgressBar(progressBar, lineCounter)
        }
        return(bingFileSize)
        file.remove("bingFileContents.txt")
        close(progressBar)
    }
    if (server == "open") {
        serverFound = 1
        lineCounter = 1
        openMapFileSize <- NULL
        progressBar <- txtProgressBar(min = 0, max = length(dataFrame$lat), 
            style = 3)
        while (lineCounter < (length(dataFrame$lat) + 1)) {
            inputLat = dataFrame$lat[lineCounter]
            inputLng = dataFrame$lng[lineCounter]
            numberOfTiles = bitwShiftL(1, zoom)
            inputLngMod = inputLng + 180
            pixX = (numberOfTiles/360) * inputLngMod
            inputLatMod = inputLat * pi/180
            n <- 2^zoom
            pixY = floor((1 - log(tan(inputLatMod) + (1/cos(inputLatMod)))/pi)/2 * 
                n)
            pixX = round(pixX)
            pixY = round(pixY)
            urlToGet = paste("http://c.tile.openstreetmap.org/", 
                zoom, "/", pixX, "/", pixY, ".png", sep = "")
            openFileNotFound = 0
            tryCatch(download.file(url = urlToGet, destfile = "openFileContents.txt", 
                quiet = TRUE, mode = "w", cacheOK = TRUE, extra = getOption("download.file.extra")), 
                warning = function(w) {
                  Sys.sleep(10)
                  print("Unable to download image from openstreetmap.  Retrying after 10 seconds...", 
                    quote = FALSE)
                  tryCatch(download.file(url = urlToGet, destfile = "openFileContents.txt", 
                    quiet = TRUE, mode = "w", cacheOK = TRUE, 
                    extra = getOption("download.file.extra")), 
                    warning = function(w2) {
                      openFileNotFound = 1
                      print("Unsuccessful.  This location will be coded as NA.", 
                        quote = FALSE)
                    })
                })
            if (openFileNotFound == 0) {
                fileSize = file.info("openFileContents.txt")["size"]$size
            }
            if (openFileNotFound == 1) {
                fileSize = "NA"
            }
            openMapFileSize = c(openMapFileSize, fileSize)
            lineCounter = lineCounter + 1
            setTxtProgressBar(progressBar, lineCounter)
        }
        return(openMapFileSize)
        file.remove("openFileContents.txt")
        close(progressBar)
    }
    if (serverFound == 0) {
        print(paste("Server name (", server, ") not recognised.  Options are 'google', 'bing', 'open'.  Exiting."), 
            quote = FALSE)
    }
}