Renk Thorsten <thorsten.i.r...@jyu.fi> writes: >> There are good sources for sea colour out there - here is one: >> >> http://oceancolor.gsfc.nasa.gov/FEATURE/IMAGES/A2008129125500.Scotland.png > >> The Northern North Sea, away from the turbidity and major river outfalls >> of the Southern North Sea, is indistinguishable from the Atlantic, the other >> side of Scotland. > > 4 West, 54 North I get an rgb value of (93, 113, 121) > 2 East, 54 North I get (31, 71, 83) > > There's pretty significant variation everywhere, but I don't see that in that > picture that the two would even be similar. > >> There are many examples in this archive, and if there >> are differences in the deep ocean colour in any of the oceans they are darned >> hard to spot. Similarly, if there is a difference between the Atlantic >> and the Mediterranean, it's very hard to see. > > We might not be after the same thing here... > > In reality, water color depends on a lot of factors: > > * light reflection at the surface, i.e. light diffuseness, intensity, wave > patterns, sky color, ... > -> we have a decent way to account for that in the shader > > * sediment and algae in the water -> water being a flowing substance, > all these are variable phenomena, rivers carry a lot of mud in spring > when the snow thaws, algae bloom seasonally,... we can't model this > realistically in any case > > * near the coast, depth and nature of the bottom -> white underwater > sand looks quite differently from overgrown rocky bottom, deep water > looks different from shallow water... we simply don't have this > information - we might get depth somehow, pass true depth to the > shader, use it to determine color, then let the shader move the vertex > up to the water surface, but it's a bit tricky. > > Given that we can't do so much realistically anyway for lack of data > (and lack of framerate - I could probably write a detailed water color > computing code, but that'd really drive framerate down), my idea is > more to re-create iconic pictures. > > When approaching Nice in sunshine, I want to see one of these postcard > Cote d'Azur pictures. When landing on a drilling rig in the Northern > Sea, I don't expect to see this deep blue. Probably in reality the > differences are driven by differences in lighting, average weather and > some sediment/algae component - but when I can't do the realistic > thing, I might as well do the iconic thing. > > Many people (including myself) seem to feel that the sea should look > different in different places. I'm entirely willing to tweak physics > here a bit to create a better illusion that one is in the place by > fulfilling the expectation. True, the actual Caribbean deep ocean is > not turquoise. Then again, the actual Caribbean city doesn't look the > Flightgear way either. But making sea color a lighter turquoise in the > Caribbean helps me to maintain the illusion that I am in the Caribbean > rather than the Northern Sea. > > Feel free to disagree, but for me creating the visual environment has > much more to do with credible illusions than with getting the physics > of the scene right (disclaimer: my position is diffferent for the > fidelity of the FDM where we can actually get the physics really right > since we have often the required amount of data).
There are also nice patterns drawn by wind and by oil. When the sea is flat, over distances on the order of hundreds of meters you have changes in the wavelets that give quite different patterns from a distance. And furthermore, there some oil floating in nice patterns seeing at different scales, generally in spiral. They're stricking when saw from space, but they are also visible from the beaches. https://docs.google.com/viewer?a=v&q=cache:P6Iom6_AjrMJ:armi.ucsd.edu/Spirals.pdf+&hl=en&pid=bl&srcid=ADGEEShQ-kOpl7JfwiDDG2SHOGs7fkAkhVrVHwuUs1tJZO9pLKhS9ks-VrdHB2k68QgP1jJ2pKH7HwSKqnzn1tCJ0GLa88JxHVR_4xbQifElWm4FlScwpk0lZ8hfTZWjJYSld-d_ryw7&sig=AHIEtbQ9vmtNjZC9WylNau0sW17FgGEe9A&pli=1 -- __Pascal Bourguignon__ http://www.informatimago.com/ A bad day in () is better than a good day in {}. ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
