geotag04.r

# Download nice-looking map-tiles for the relevant location
photo_map <- openmap(upperLeft  = c(max(file_info$lat, na.rm = T) + 0.2, min(file_info$lon, na.rm = T) - 0.2),
                     lowerRight = c(min(file_info$lat, na.rm = T) - 0.2, max(file_info$lon, na.rm = T) + 0.2),
                     type = "stamen-watercolor")

# we need to turn our coordinates into an sp object in order to
# properly project the points onto the map.
photo_points <- SpatialPoints(na.omit(file_info[,c("lon", "lat")]),
                              CRS("+proj=longlat +ellps=WGS84 +datum=WGS84"))

# transform the lon lat coordinates to the same projection as the map tiles.
photo_points <- spTransform(photo_points, photo_map$tiles[[1]]$projection)

# plot the map and locations of the pictures
png("jpg_geotags01.png", photo_map$tiles[[1]]$yres/3, photo_map$tiles[[1]]$xres/3, type = "cairo")
plot(photo_map)
plot(photo_points, add = T, pch = 19, cex = 0.8)
plot(photo_points, add = T, pch = 19, cex = 0.5, col = rainbow(length(photo_points)))
dev.off()