slideView

Description

Two images are overlaid and a slider is provided to interactively compare the two images in a before-after like fashion. img1 and img2 can either be two RasterLayers, two RasterBricks/Stacks or two character strings. In the latter case it is assumed that these point to .png images on the disk.

This is a modified implementation of http://bl.ocks.org/rfriberg/8327361

Usage

## S4 method for signature 'RasterStackBrick,RasterStackBrick'
slideView(img1, img2, r = 3,
  g = 2, b = 1, na.color = mapviewGetOption("na.color"),
  maxpixels = mapviewGetOption("plainview.maxpixels"), ...)

## S4 method for signature 'RasterLayer,RasterLayer'
slideView(img1, img2,
  col.regions = mapviewGetOption("raster.palette")(256),
  na.color = mapviewGetOption("na.color"),
  maxpixels = mapviewGetOption("plainview.maxpixels"))

## S4 method for signature 'character,character'
slideView(img1, img2)

## S4 method for signature 'ANY'
slideview(...)

Arguments

Details

Compare two images trough interactive swiping overlay

Methods (by class)

• img1 = RasterLayer,img2 = RasterLayer: for RasterLayers

• img1 = character,img2 = character: for png files

• ANY: alias for ease of typing

Author(s)

Tim Appelhans

Stephan Woellauer

Examples

### raster data ###
library(sp)
library(raster)

data(poppendorf)

stck1 <- subset(poppendorf, c(3, 4, 5))
stck2 <- subset(poppendorf, c(2, 3, 4))
slideView(stck1, stck2)

## Not run: 
### example taken from
### http://www.news.com.au/technology/environment/nasa-images-reveal-
### aral-sea-is-shrinking-before-our-eyes/story-e6frflp0-1227074133835

library(jpeg)
library(raster)

web_img2000 <- "http://cdn.newsapi.com.au/image/v1/68565a36c0fccb1bc43c09d96e8fb029"

jpg2000 <- readJPEG(readBin(web_img2000, "raw", 1e6))

# Convert imagedata to raster
rst_blue2000 <- raster(jpg2000[, , 1])
rst_green2000 <- raster(jpg2000[, , 2])
rst_red2000 <- raster(jpg2000[, , 3])

img2000 <- brick(rst_red2000, rst_green2000, rst_blue2000)

web_img2013 <- "http://cdn.newsapi.com.au/image/v1/5707499d769db4b8ec76e8df61933f2a"

jpg2013 <- readJPEG(readBin(web_img2013, "raw", 1e6))

# Convert imagedata to raster
rst_blue2013 <- raster(jpg2013[, , 1])
rst_green2013 <- raster(jpg2013[, , 2])
rst_red2013 <- raster(jpg2013[, , 3])

img2013 <- brick(rst_red2013, rst_green2013, rst_blue2013)

slideView(img2000, img2013)

## End(Not run)

Results