Summary plot requirements

info If the natural resolution of the instrument produces data whose resolution is lower than what GAIA prefers, it is possible to use smaller thumbnails and less vertical pixels in keograms. However, the reduced sizes must still be a power of two.


  • keograms are mandatory for all imaging instruments. Widebeam riometers are excluded, but GAIA-compatible CDF data files (see GaiaCdfFileFormat) are required instead so that line plots can be created on-demand in lieu of keograms.
  • 720 (horizontal) by 64 (vertical) pixels that cover the whole UT-day
  • the keograms start at 0000UT (inclusive) and end at 0000UT (exclusive) the following day
  • one pixel column corresponds to two minutes

Thumbnails (if appropriate)

  • 64 by 64 pixels
  • bubble how do we deal with smaller thumbnails scaled at the client side in the browser?

Greyscale vs. colour

  • GAIA uses 8-bit greyscale 0..255
    • The value 254 corresponds to bad data (use in cases where there would normally be data in this pixel location but in this instance it is bad)

    • The value 255 corresponds to do not plot (use in cases where there is never any data at this pixel location)

    • bubble only lossless compression can preserve the do not plot and bad data values. At the moment we are using PNG.
  • If the source data are in colour the thumbnails and keograms should be RGB colour images with 8-bit range in each colour plane (i.e. 24-bit colour images)
    • bubble The colour images can be lossy compressed. At the moment we are using JPG.
  • The thumbnails and keogram for one UT-day must use the same data range. However, this range may vary on UT-daily basis (if preferred by the data provider)

Colour palettes

  • Colour palette selection applies only to greyscale source images.
  • At first, GAIA provides linear and nonlinear greyscales and a couple of pseudo-colour palettes.
  • bubble Not everybody will be happy with the choice of colour palettes and we will most likely need to add new palettes in future.
  • bubble We should add one "reverse" greyscale palette as suggested by one end-user. This may improve the results of printing on paper.

Image orientation

Data providers must indicate the ImageOrientation for their images (all images must be orientated in the same way.

File naming convention

Summary and data filenames must follow some simple requirements:

  • the summary data (keograms and thumbnails) are stored in monthly directories with a tree projectname/stationabbreviation/channel/YYYY/MM/
  • all thumbnails for one day are stored in the monthly directories in a zip-file with a name
  • the keogram and the corresponding thumbnail zip-file are both stored in the monthly directory
  • a keogram filename must be in the following format projectname_stationabbreviation_channel_YYYYMMDD.[png|jpg]
  • a thumbnail filename must be in the following format projectname_stationabbreviation_channel_YYYYMMDD_HHMM.[png|jpg]
  • For keograms the timestamp is the start of the UTC day, for thumbnail images it is the start of the corresponding minute.
  • Images and data files are stored in separate subdirectories for each project.

info All letters in the path and filenames must be lower-case.
info The project names, station abbreviations and channel descriptions should be something that make sense. For most projects, there already is an existing convention and that should be followed within reason.
warning When creating summary data for a new instrument, first check whether there is a matching channel already defined in the database.

An example of the correct ZIP filename for the NORSTAR Athabasca (ATHA) camera data using a 557.7nm filter would be norstar/atha/557.7nm/2006/03/ and the contents of this file would be


and so on but without an extra directory into which the files would be unzipped.

The correct filename for the keogram would be


tip Check the projects web page for correct format strings to use for your project. You'll need an administrator to enter your project details into the master database first.

Image metadata

It may be helpful if you add some metadata to the keogram and thumbnail images, though there is no requirement to do so. If you choose to please follow the ImageMetaDataGuidelines so that all of the metadata is compatible.

Topic revision: r16 - 2010-01-21 - 08:20:47 - SteveMarple
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