rgee animations

animation_01.R

library(rgee)
library(magick)

ee_Initialize()

col <- ee$ImageCollection("JRC/GSW1_1/YearlyHistory")$map(function(img) {
  year <- img$date()$get("year")
  yearImg <- img$gte(2)$multiply(year)
  despeckle <- yearImg$connectedPixelCount(15, TRUE)$eq(15)
  yearImg$updateMask(despeckle)$selfMask()$set("year", year)
})

appendReverse <- function(col) col$merge(col$sort('year', FALSE))

# -----------------------------------
# 1 Basic Animation - Ucayali Peru
# -----------------------------------

bgColor = "FFFFFF" # Assign white to background pixels.
riverColor = "0D0887" # Assign blue to river pixels.

## 1.1 Create the dataset
annualCol = col$map(function(img) {
  img$unmask(0)$
    visualize(min = 0, max = 1, palette = c(bgColor, riverColor))$
    set("year", img$get("year"))
})
basicAnimation <- appendReverse(annualCol)


## 1.2 Set video arguments
aoi <- ee$Geometry$Rectangle(-74.327, -10.087, -73.931, -9.327)
videoArgs = list(
  dimensions = 600, # Max dimension (pixels), min dimension is proportionally scaled.
  region = aoi,
  framesPerSecond = 10
)

## 1.3 Download GIF
animation_ucayali <- basicAnimation$getVideoThumbURL(videoArgs)
ucayali_gif <- tempfile()
download.file(animation_ucayali, ucayali_gif)

## 1.4 Read GIF using magick
animation <- image_read(ucayali_gif)
animation_info <- image_info(animation)
ani_geom <- sprintf("%sx%s", min(animation_info$width),min(animation_info$height))
new_animation <- image_extent(animation, ani_geom, gravity = "NorthWest")
years_info <- basicAnimation$aggregate_array("year")$getInfo()

## 1.5 Add text annotations
for (index in seq_along(years_info)) {
  new_animation[index] <- new_animation[index] %>% 
    image_annotate(
      text = years_info[index], 
      size = 30, 
      color = "#E5E4E5",
      location = "+190+40", 
      font="consolas",
      boxcolor = rgb(0,0,0)
    ) %>% 
    image_annotate(
      text = "JRC/GSW1_1/YearlyHistory", 
      size = 13, 
      color = "#E5E4E5",
      location = "+10+550", 
      font="consolas",
      boxcolor = rgb(0,0,0)
    )
}

image_write_gif(
  image = new_animation, 
  path = "/home/csaybar/demo_01.gif"
)

# -----------------------------------
# 2. Fading history animation
# -----------------------------------

## 2.1 Create the dataset
bgImg <- ee$Image(1)$visualize(palette = bgColor)
fadeFilter <- ee$Image(1)$visualize(palette = bgColor, opacity = 0.1)
fadeFilterCol <- col$map(function(img) {
  imgVis <- img$visualize(palette = riverColor)
  imgVis$blend(fadeFilter)$set('year', img$get('year'))
})

yearSeq <- ee$List$sequence(1984, 2018)
year_fun <- function(year) {
  fadeComp = fadeFilterCol$filter(ee$Filter$lte("year", year))$sort("year")$mosaic()
  thisYearImg = col$filter(ee$Filter$eq("year", year))$first()$visualize(
    palette = riverColor
  )
  bgImg$blend(fadeComp)$blend(thisYearImg)$set("year", year)
} 

fadeCol <- ee$ImageCollection$fromImages(
  images = yearSeq$map(ee_utils_pyfunc(year_fun))
)


## 2.2 Set video arguments
aoi <- ee$Geometry$Rectangle(-74.327, -10.087, -73.931, -9.327)
videoArgs = list(
  dimensions = 600, # Max dimension (pixels), min dimension is proportionally scaled.
  region = aoi,
  framesPerSecond = 10
)

## 2.3 Download GIF
animation_ucayali <- fadeCol$getVideoThumbURL(videoArgs)
ucayali_gif <- tempfile()
download.file(animation_ucayali, ucayali_gif)

## 2.4 Read GIF using magick
animation <- image_read(ucayali_gif)
animation_info <- image_info(animation)

ani_geom <- sprintf("%sx%s", min(animation_info$width), min(animation_info$height))
new_animation <- image_extent(animation, ani_geom, gravity = "NorthWest")
years_info <- fadeCol$aggregate_array("year")$getInfo()

## 2.5 Add text annotations
for (index in seq_along(years_info)) {
  new_animation[index] <- new_animation[index] %>% 
    image_annotate(
      text = years_info[index], 
      size = 30, 
      color = "#E5E4E5",
      location = "+210+40", 
      font="consolas",
      boxcolor = rgb(0,0,0)
    ) %>% 
    image_annotate(
      text = "JRC/GSW1_1/YearlyHistory", 
      size = 13, 
      color = "#E5E4E5",
      location = "+10+520", 
      font="consolas",
      boxcolor = rgb(0,0,0)
    )
}

## 2.6 It seems there is a small bug here, preview looks great but not 'magick::image_write_gif'
## exportation. 
new_animation

# image_write_gif(
#   image = new_animation, 
#   path = "/home/csaybar/demo_02.gif"
# )