On Sunday 18 January 2009 11:04:13 Florian El Ahdab wrote: > So here are my questions: > - has anyone ever worked with S57 and OGR and/or Qgis?
This discussion came up on the gpsdrive list and i've included the pertinent parts for you review: ---------------------------------------------------------------- From Hamish Bowman: For ENC support in GpsDrive it is still my hope that libS52 could be used to render the data, in a similar way as Mapnik is rendering OSM data now. see http://apps.sourceforge.net/mediawiki/gpsdrive/index.php?title=Marine_Howto (please help improve the wiki page!) http://grass.osgeo.org/wiki/BSB_data http://grass.osgeo.org/wiki/S-57_data#libS52 http://openev.cvs.sourceforge.net/openev/contrib/S52/ 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. ---------------------------------- response: me, requesting a tutorial to review the material. --------------------------------------------------- response: Hamish --------------------------------------- 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. ------------------------------ since qgis is used extensively in preparing maps for gpsdrive and there is significant interest wrt marine navigation where most charts are S-57 vectors the long term goal (very long term) is to move toward a plugin for qgis to manipulate the data in order to make it available to gpsdrive. However its a bit of a challenge as you can see, I'm not a developer, rather just a listee with sailboat so I keep interested in this stuff. > - I believe Qgis doesn't use the S57 sublayers and that's why nothing gets > displayed. Is there any chance that I am right? If I am right, Your most likely correct. > I would like > to help with the implementation for this kind of problem. Can anyone in the > dev team give me directions on where to begin (I have spent some time in > the source and API of both Qgis and GDAL and feel I can contribute here...) Perhaps a good start would be reviewing the submitted material above and then following the directions and advice of the qgis development team. Best of luck /ch _______________________________________________ Qgis-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/qgis-user
