On vendredi 16 janvier 2009, Martin Spott wrote: > James Turner wrote: > To the current state we have a coastline around each 'isolated' > continent or island which is either made from a single closed polygon > (which could be GSHHS) or from the outline around a couple of adjacent > polygons (VMap0 political boundaries). To get an overview, please check > here: > > http://wiki.osgeo.org/wiki/Geodata_Repository#PostGIS_serving_vector_data > > This coastline is the basic factor for a simple principle: Everything > inside this coastline is counted as ground, the entire area outside the > coastline is "Ocean". The same principle applies to lakes - just in the > reverse order: Everything inside the lake shoreline is water. > > So, even if our STRM elevation grid would indicate some sort of > elevated ground outside our coastline, it's going to get clipped out > due to the given principle. In contrast, if there's no elevation data > for an area inside the coastline, then the ground is still going to get > extended in accordance with the coastline .... but at sea level. > There's a nice example for these corner cases if you approach RWY 24 at > TNCE in the 1.0.1 Scenery. > > I'm proposing a similar but somehow opposing schema (talking is cheap ;-) > Let us have the seabed modelled using bathymetry data, clipped against > the same coastline which we're using to clip the ground elevation, > limit the maximum 'elevation' of the seabed to the elevation of the > respective coastline, which is presumably at MSL for all ocean > shorelines - or the individual elevation of the respective lake. > Probably limit the seabed elevation to a few centimetres below to allow > for some nice waves .... > I don't see any reason why and how this approach would set KSFO under > water. > > > Also, is global (even crude) coastal bathymetry data available? > > Yes, I even had a copy of global bathymetry data on my local disk few > years ago, but lost it due to sort of a crash (well, the data is still > sitting there, but I have to re-assemble the partitions before I'm able > to read it). > > Cheers, > Martin.
I did not understood everything about the content of that topic, since the technical which is involved is "flying" over of my low know how. I would like only say ( again , because said before) that the coastline which is close to my favorite area , the French coastline on Mediterranean sea, was better with the 9.8 scenery. It is sure that the last version is mostly better than the 1.0, however it is not so right than it was with the old 9.8 version. I understand that making the scenery is a very difficult work. From the data which which are freely available it is difficult to get the same quality that we can have now with google 3D or IGN (France). In addition to it, i worry that we are not able to get the right connection from the generic sea tile to the coastline tile ( difference of level) So, before to spend some time to try to develop any water shader, it would be better to invest time to try to get a consistent sea surface. Cheers -- Gérard http://pagesperso-orange.fr/GRTux/ J'ai décidé d'être heureux parce que c'est bon pour la santé. Voltaire ------------------------------------------------------------------------------ This SF.net email is sponsored by: SourcForge Community SourceForge wants to tell your story. http://p.sf.net/sfu/sf-spreadtheword _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
