Super Overlay Tiler  -  new version 0.3 (dec.06) 

The Super overlay tiler segments a raster image of large dimensions into a series of small format images following a procedure described in KML 2.1 standard. The procedure also generates a tree like structure of KML files which link these images, consenting the fast publication in Google Earth of a large raster image. The georeferenciation of the image is achieved by simply positioning two placemarks in Google Earth onto two points for which the pixel coordinates of the image are known. In the 0.2 version is also possible to directly insert coordinates in the command line with the -ll: option (lowercase double L).

To function correctly the program requires the ImageMagick library.

1) Download, unpack and install the RMagick Ruby binary gem (1.13.0) for win32 library from this site

2) Create a directory (eg. c:\overlay)

3) Download the Super Overlay Tiler program, unpack it and save it into the same directory

4) Move the image file to segment into the same directory (eg. c:\overlay\115010.tif)

ver. 0.2 - Following points 5,6 and 7 can be substituted by direct typing of lat and long coordinates with th -ll: option described later.

5) Identify two reference points for each image, preferably close to the diagonal ends, far from each other. The pixel coordinates for each of these points must be found in a paint program like Gimp, PaintshopPro or Photoshop

6) Create two placemarks in Google Earth which correspond to the two created above in line 5 and insert the horizontal and vertical co ordinates into the Description placemark field, separating them with a comma. (eg. 6216,5592)

7) Save the placemarks in .kml format in the same directory as the images and name them with the same name as the image followed by “_1” and "_2" (eg. c:\overlay\115010_1.kml and c:\overlay\115010_2.kml)

8) Open a command window or type the following command from the Run

c:\ overlay\sot –i:imagename –name:description

new options in 0.2 version:

-ll: north, south, east, west  (in decimal degrees, separated by commas)

-q: quality of jpg compression (from 1 to 99)

new options in 0.3 version:

-low (to force a BoxFilter reducing filter instead of LanczosFilter - see ImageMagick manual for more details)

(The -i: option is mandatory, the -name: , -ll:, -q:, -low are optionals)

eg.. sot -i:trial.jpg -q:85 -name:trial -ll:45.345,45.213,8.04,7.96

The procedure creates a new directory with the image name and also creates all the reduced files and the .kml files which form the tree of the super overlay structure.

In the 0.2 version, the generated images will have the same format of the original one to be tiled.

The entry point link to call from within Google Earth is a file inside the created folder that always has the name index.kml.

Attention! All the links (images and .kml files) are relative and not absolute, so you can move the genrated folder from local to server address. If GE will give you errors in reading file, try to clear the cache (close GE and restart!)

The folder may be transferred via FTP onto a webserver so the image will be accessible to a network, or it may be copied to other drives or onto a CD.

If you want to distribute the created image on the web, don't forget to add a correct MIME type for a .kml file, wich is

application/vnd.google-earth.kml+xml kml

application/vnd.google-earth.kmz kmz

If you have any problems, contact me