Charts II: NGA - 2700 Charts

[cagney]

The first "Chart" thread was started to discuss and convert all the NZ carts.
Now, through this thread -http://www.cruisersforum.com/forums/...tml#post718487, I have found out that there are ~2700 chart pictures, world wide available on the net. The pictures are in tiles stitched together, to one flash picture, something like a new version of the old hdr files.
Scripts and websites are available to "dezoomify" the pictures on the NOAA/NGA website and download the result as a jpg or png picture.
These pictures are rather large and need to be made smaller.
Then it's just the normal georeferencing etc to make a kap file.
The pictures are "pixelperfect" and a pleasure to work with.
Here is the central website: NOAA's On-Line Chart Viewer
The directories behind the website: Index of /NGAViewer
A Pythonscript that downloads a stitched together Jpg: Help:Zoomable images/dezoomify.py - Wikimedia Commons
A Ruby script to do the same thing: https://gist.github.com/770310
A webscript in html/js/php:https://gist.github.com/770310
A website to do the job:Dezoomify. This site produces a png files.
The format of the links to feed both scripts and the web site is similar to this:

Chart 57440

All this is a very slow process screaming for a cluster of linux boxes.
When the ruby script came to this

Stitching 56 x 76 = 4256 tiles...

my load average was around 13 and the box was totally unresponsive for a long time. Be warned!

Let us together work on this. First the picture wizards ... on how to make these pictures small enough and good enough ...please.

Thanks to NGA for the web site. A worldwide coverage of freely available charts is now within reach. If only BA could take the hint from NOAA, NGA, LINZ and the Brazilian Hydrographer........

Thomas