ee_utils_gif_creator: Create a GIF from an Earth Engine ImageCollection

In csaybar/rgee: R Bindings for Calling the 'Earth Engine' API

Description

Create an GIF (as a magick-image object) from a EE ImageCollection. Note: Animations can only be created when ImageCollections is composed by RGB or RGBA image. This can be done by mapping a visualization function onto an ImageCollection (e.g. ic$map(function(img) img$visualize(...))) or specifying three bands in parameters argument (See examples). ee_utils_gif_creator is a wrapper around ee$ImageCollection$getVideoThumbURL.

Usage

ee_utils_gif_creator(ic, parameters, quiet = FALSE, ...)

Arguments

ic	An ee$ImageCollection.
parameters	List of parameters for visualization and animation. See details.
quiet	Logical. Suppress info message.
...	parameter(s) passed on to download.file

Details

The parameters argument is identical to visParams (See rgee::Map$addLayer), plus, optionally:

• dimensions: A number or pair of numbers in format c(WIDTH,HEIGHT). Max dimensions of the thumbnail to render, in pixels. If only one number is passed, it is used as the maximum, and the other dimension is computed by proportional scaling.

• crs: A CRS string specifying the projection of the output.

• crs_transform: The affine transform to use for the output pixel grid.

• scale: A scale to determine the output pixel grid; ignored if both crs and crs_transform are specified.

• region: ee$Geometry$Polygon, GeoJSON or c(E,S,W,N). Geospatial region of the result. By default, the whole image.

• format: String. The output format (only 'gif' is currently supported).

• framesPerSecond: String. Animation speed.

Value

A magick-image object of the specified ImageCollection.

Author(s)

Jeroen Ooms

See Also

Other GIF functions: ee_utils_gif_annotate(), ee_utils_gif_save()

Examples

## Not run: 
library(rgee)

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
)

## 1.2 Download, display and save the GIF!
animation <- ee_utils_gif_creator(basicAnimation, videoArgs, mode = "wb")
get_years <- basicAnimation$aggregate_array("year")$getInfo()
animation %>%
  ee_utils_gif_annotate("Ucayali, Peru") %>%
  ee_utils_gif_annotate(get_years, size = 15, location = "+90+40",
                        boxcolor = "#FFFFFF") %>%
  ee_utils_gif_annotate("created using {magick} + {rgee}",
                        size = 15, font = "sans",location = "+70+20") ->
  animation_wtxt
gc(reset = TRUE)
ee_utils_gif_save(animation_wtxt, path = paste0(tempfile(), ".gif"))

## End(Not run)

csaybar/rgee documentation built on March 11, 2021, 5:48 a.m.