I am a meteorologist and have a passion for 3D (volumetric) clouds and am always looking for a better way to animate clouds. For about 5 years I have been using Lightwave with a plugin called Ogo-Taiki. Like TG2 this plugin uses procedural textures and cannot specify individual clouds just a sky populated by clouds the number of, density of and form of which can be controlled. Like the Technology Preview of TG2, Ogo-Taiki requires long render times but that's the cost of realism.
I divide cloud animation into three parts. 1. large scale motion of clouds in the atmosphere i.e. clouds follow the winds, 2. growth/decay - evolution of individual cloud elements i.e. is condensation or evaporation dominant. This could be expressed as vertical growth in cumulonimbus (thunderstorm) clouds or increasing density in stratiform clouds or a combination of these or other factors you may come up with. 3. Small scale variations, these I treat as random variations that have smooth transitions from frame to frame. In other words I do not want things just popping into and out of existence for a single frame. They are fine detail which follow from the physical processes that cause the clouds. Examples are the cauliflower-like bulges on a cumulus cloud or thin patches in a deck of stratus clouds, or edge detail (wispy vs. hard). At the landscape scale we do not worry about physical reality of these small small variations, they are aesthetic detail and add realism.
In TG2 a transform shader is great for #1 (in Lightwave an object is moved and the clouds follow the motion of the object to which the texture is assigned).
I am new to TG2 and because I could not do what I wanted with clouds in TG I never really used it much. So those of you who know TG2 much better than I do (almost everyone!) try to divide your cloud animations into three parts and deal with each part separately. It really does simplify the process. Move the clouds with the translate function of a transform shader, and come up with techniques on increasing vertical extent and/or density for item #2 and come up with ways to manipulate procedural textures for fine detail in item #3.
Here is hoping that TG2 will some day allow a volume, defined by a 3D object to be filled with a 3D procedural texture to create an individual 3D cloud. In Lightwave this seems to be an easier way to get individual clouds than a particle system.
While I learn TG2, anyone have any ideas? By the way the node network of TG2 is great!
-Steve Horstmeyer
