[ gpsdrive ] making use of AIS data

[Hamish]

Hamish wrote:
> > the very tricky bit is choosing which layers to include. the S-52
> > gives recommendations of which features to display based on map
> > scale class, I'd say reuse those. But you would have to enter
> > that data by hand. If someone provides a list of layernames
> > per scale band, I might do the rest.
> 
> If you could provide me with a quick and dirty briefing or tutorial,
> I would  be interested in tacking this as it would be a good
> learning lesson. 


see SCAMAX and SCAMIN entries in the libS52 CVS file doc/att.txt,

for each token these control which map scales (e.g. 1:25,000-1:100,000)
the feature should be rendered.

and read through the remarks in S52CS.c in the libS52 source
// S52CS.c : Conditional Symbologie procedure 3.2 (CS)

(ignore the code, just look at the comments...)

and the IHO PDF spec docs,
http://grass.osgeo.org/wiki/S-57_data#GRASS_S-52_interface_for_rendering_S-57_data


and you may see why I defer :). It's all there & coded, but a bit daunting
to me.

My idea is a little wrapper C program around S52CS.c to export tokens
based on a list of scales would help us make a table which we could use
in developing the list of layers for the WMS request.


Hamish