German Astrophysical Virtual Observatory
 
 

Home

About GAVO

Documentation

External

Site Map


Intranet

SkyWalker

Here we publish a solution to a problem, that sometimes hampers the publication of observation images. If an image is too big to be published in one piece, (e.g. the size of 150 MB) then we divide the image into convenient pieces, and with the help of some lines of JavaScript-code and the library, the image slices can be viewed with a browser, and even behind a slow connection they load in reasonable time. The navigation is managed through a downscaled image.

What's required? Nothing more than 3 bundles of Open Source software

  • Perl and the appropriate module for gimp, Gimp.pm (may be the module has to be installed from CPAN)
  • gimp (any reasonable Linux-distribution should come with both)
  • dynapi-lib, and
  • the script and some editing of the HTML-page below.
The Perl-script contains only basic error-checking. The script is written with the situation in mind, that the huge image is tiled, and the tiles do have some overlap.

The HTML-page has to be adapted: the number of images, their size and the window-size have to be tuned (see the "Constants"-section), the location of the images, the name-prefix has to be set in function exchangeIma(), and some constants (search for img/).

The UDF-Skywalker contains 625 images with prefix "UDF_", size each 628x628, in a directory "img/".

Download the Sky-Walker files: Skywalker-Sources.

Thanks to K. Jahnke and S. Sanchez from AIP for making this code available.