I haven’t used World Wind for a while because I found the Virtual Earth plugin essential and it didn’t work with the latest release. Thanks to the comments from Bull UK in this post, I have been able to upgrade to version 1.4 and enjoy some of the new features which include the 3D connexion plugin for my Space Navigator, the Virtual Earth plugin and lots of other enhancements which make the program even nicer to use.
I was interested in testing the Global Flood plugin for World Wind and am pleased to say that it worked very well, though not at the zoom level required for the lesson I describe here. When zooming in to street level the flood layer fills the screen regardless of the elevation of the terrain and the Google Earth option works rather better. However, if the object of the lesson is to look at the impacts of sea level change on a regional scale, then World Wind is an improvement on the Google Earth technique, and the level of flooding can be controlled by a simple slider. Observe the “flood of blood” invading the Gold Coast!
Click to enlarge Global Flood plugin in WorldWind
The reason your google one is more “accurate” is because it uses just a few pre-generated images for that one location. The World Wind one renders the water surface in 3d in the application itself where ever you are looking on the globe at any elevation you specify, so its accuracy is limited by the current level of terrain loaded in WW and the precision available from your graphics card in calculating where the terrain and the flood mesh intersect. You can cut down on the z-buffer artifacts by cranking the terrain exaggeration all the way up to 20x in the alt-w window. Just don’t expect it to look realistic up close then.
-Erik (one of the WW flood plugin authors)
Actually, now that I look closer, the GE technique is similiar. It looks like the only difference would be the source DEM. Is the GE one actually accurate at street level?
In Google Earth its not necessary to exaggerate the vertical scale by anything more than 1.5 to 2. It seemed more accurate at street level to me, though I really like your World Wind solution for larger areas.
I don’t have the pay version of GE to test, but probably just GE’s 3d precision is better. I guess there is an advantage to having money to throw at 3d graphics programmers.