I would say that the implementation of caustics within the final commercial release of TG2 even if its only the High-end TG2 Deep Edition would be a logical edition to the feature set, since the TG2 FAQ dose say that TG2 will be capable of underwater images.
Given that TG2 has GI as part of its rendering and the fact that caustics are a part of GI then I don't see why not as long as TG2 supports Shadowed and Volumetric caustics I don't mind.
They would have to consider and there is no way round this both reflection and refraction of light via ray-tracing; there is not way round this.
Since you dealing with underwater caustics you will need to have the render consider light transport through water, important factors to consider fresh vs. salt water, water clarity (Parts per-billion of sedimentation content of the water body which would affect the way light is transmitted), Salinity level of the water (Sea water due to its salt content transmits light differently form fresh), the geometry of the receiving surface, and support both reflective and refractive caustics among other things.
Ideally the caustics should change with changes in the water surface as should the shadows they cast as any one who's ever dived (Not Me) in shallow water will tell you about the caustics changes seen on the ocean floor.
It would be good if caustics could be cast on to other objects such as rocks in the water and so on. On the whole then these are a few things to think about for the future and as a subject area caustics are been intensely studied in the field of CGI and are not some thing to be rushed into without due care and consideration.
VUE form what I understand has the ability to do caustics already so this is an area where Terragen is lagging behind right now, but may gain this capability some time in future if not for the first commercial release but in a latter update.
Regards to you.
Cyber-Angel
