Package 'slideview'

Title: Compare Raster Images Side by Side with a Slider
Description: Create a side-by-side view of raster(image)s with an interactive slider to switch between regions of the images. This can be especially useful for image comparison of the same region at different time stamps.
Authors: Tim Appelhans [cre, aut], Stefan Woellauer [aut]
Maintainer: Tim Appelhans <[email protected]>
License: MIT + file LICENSE
Version: 0.2.0
Built: 2024-11-05 04:42:56 UTC
Source: https://github.com/r-spatial/slideview

Help Index


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.

NOTE: In case you want to include multiple slideviews in one page in a Rmd or flexdashboard we highly recommend using package widgetframe. Also, make sure to use different image names and/or labels for each of the RasterLayers/Bricks/Stacks. Otherwise things will likely not work properly.

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

Usage

## S4 method for signature 'RasterStackBrick,RasterStackBrick'
slideView(
  img1,
  img2,
  label1 = deparse(substitute(img1, env = parent.frame())),
  label2 = deparse(substitute(img2, env = parent.frame())),
  r = 3,
  g = 2,
  b = 1,
  na.color = "#BEBEBE",
  maxpixels = 1e+07,
  ...
)

## S4 method for signature 'RasterLayer,RasterLayer'
slideView(
  img1,
  img2,
  label1 = deparse(substitute(img1, env = parent.frame())),
  label2 = deparse(substitute(img2, env = parent.frame())),
  legend = TRUE,
  col.regions = viridisLite::inferno(256),
  na.color = "#BEBEBE",
  maxpixels = 1e+07
)

## S4 method for signature 'RasterStackBrick,RasterLayer'
slideView(
  img1,
  img2,
  label1 = deparse(substitute(img1, env = parent.frame())),
  label2 = deparse(substitute(img2, env = parent.frame())),
  legend = TRUE,
  r = 3,
  g = 2,
  b = 1,
  col.regions = viridisLite::inferno(256),
  na.color = "#BEBEBE",
  maxpixels = 1e+07,
  ...
)

## S4 method for signature 'RasterLayer,RasterStackBrick'
slideView(
  img1,
  img2,
  label1 = deparse(substitute(img1, env = parent.frame())),
  label2 = deparse(substitute(img2, env = parent.frame())),
  legend = TRUE,
  r = 3,
  g = 2,
  b = 1,
  col.regions = viridisLite::inferno(256),
  na.color = "#BEBEBE",
  maxpixels = 1e+07,
  ...
)

## S4 method for signature 'character,character'
slideView(
  img1,
  img2,
  label1 = deparse(substitute(img1, env = parent.frame())),
  label2 = deparse(substitute(img2, env = parent.frame()))
)

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

Arguments

img1

a RasterStack/Brick, RasterLayer or path to a .png file

img2

a RasterStack/Brick, RasterLayer or path to a .png file

label1

slider label for img1 (defaults to object name)

label2

slider label for img2 (defaults to object name)

r

integer. Index of the Red channel, between 1 and nlayers(x)

g

integer. Index of the Green channel, between 1 and nlayers(x)

b

integer. Index of the Blue channel, between 1 and nlayers(x)

na.color

the color to be used for NA pixels

maxpixels

integer > 0. Maximum number of cells to use for the plot. If maxpixels < ncell(x), sampleRegular is used before plotting.

...

additional arguments passed on to repective functions.

legend

whether to plot legends for the two images (ignored for RatserStacks/*Bricks).

col.regions

color (palette).See levelplot for details.

color

the color palette to be used for visualising RasterLayers

Details

Compare two images trough interactive swiping overlay

For slideView there are a few keyboard shortcuts defined:

  • space - toggle antialiasing

  • esc - zoom to layer extent

  • enter - set zoom to 1

  • ctrl - increase panning speed by 10

Methods (by class)

  • img1 = RasterLayer,img2 = RasterLayer: for RasterLayers

  • img1 = RasterStackBrick,img2 = RasterLayer: for RasterStackBrick, RasterLayer

  • img1 = RasterLayer,img2 = RasterStackBrick: for RasterLayer, RasterStackBrick

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

  • ANY: alias for ease of typing

Author(s)

Tim Appelhans

Stephan Woellauer

Examples

if (interactive()) {
### 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, label1 = "before", label2 = "after")
}