himago

Download high-resolution images taken by the Himawari 8 satellite. A command line tool written in Go.

Overview

Images of the Asia-Pacific region taken by Himawari 8 can be viewed online at http://himawari8.nict.go.jp/. Each image of the Earth is composed of a grid of Tiles, allowing the user to freely pan and zoom. Himago downloads all images and stitches them together.

Examples

Install

go get github.com/tscott0/himago

Build

$ git clone https://github.com/tscott0/himago.git
$ cd himago/cmd/himago/
$ go build

Usage

usage: himago [--help] [-z zoom] [-b band] [-o output_file]
              [-y year] [-m month] [-d day] [-h hour] [-m minute] [-s second]

  -b, --band value
    	Electromagnetic band. Accepts integers between 1 and 16 inclusive
    	If a band is not specified a full-colour image will be produced.
  -B, --bg value
    	The background colour in hex format (default #000000,)
  -d, --day int
    	The day of the month the image was taken e.g. 30 (default 29)
  -F, --fg value
    	The foreground colour in hex format (default #ffffff,)
  -h, --hour int
    	The hour the image was taken in 24-hour format e.g. 16 means 4pm (default 15)
  -i, --minute int
    	The minute the image was taken.
    	Reverts to last 10min multiple e.g. 15 becomes 10 (default 45)
  -m, --month int
    	The month of the year the image was taken e.g. 5 means May (default 4)
  -o, --output string
    	The name of the file to write to (default "output.png")
  -y, --year int
    	The year the image was taken e.g. 2016 (default 2017)
  -z, --zoom value
    	Zoom level 1-5 (default 2)

Zoom

Changing the zoom level will alter the resolution of the image created. By default zoom level will be set to 2, producing 1100x1100 pixel image. Turning it up to 5 will produce a 8800x8800 pixel image or 77.4 megapixels.

The JMA have made generously made these images freely available. While this tool might be useful for wallpapers, please don't abuse it by downloading hi-resolution images regularly.

Zoom  Grid   Resolution
1     1x1    550  x 550
2     2x2    1100 x 1100
3     4x4    2200 x 2200
4     8x8    4400 x 4400
5     16x16  8800 x 8800

Acknowledgements

• Japan Meteorological Agency
• NICT
• Michael Pote created a script that inspired many similar tools like this.
• Jacob Kelley for his excellent work on himawari.js

Known issues

• Unrealistic colours: According to Wikipedia, the images returned are true-colour. Looking at the colour of Australia, in particular, the colours don't look accurate. Correcting the colour to make it appear more natural looks complicated.
• Occasionally will get 404 errors. Himago doesn't handle these automatically so it would require the user to specify a different date or time.

TODO

• Pass number of rollback attempts on the command line. Maximum?
• JPEG output format (inferred from filename -o)
• Percentage completion in-line?
• Download speed in-line
• Summarise output image: location, file size, dimensions, format, cropping?
• Cropping functionality
  • Just crop image before writing
• Option to save intermediate Tile images
  • Improve by skipping downloads for images that aren't needed.
• --version
• 404 should fail but be handled better
• Consider using https://github.com/pkg/errors
• Measure performance

License

MIT.