Quote from: Oshyan on April 05, 2018, 04:06:13 PM
All your answers to why it's possible are in the notes of that project. For example:
"Area lights give great direct light results, but their shadows and scattering in the fog are very rough approximations in this project."
"Direct light soft shadows are implemented using PCSS - the technique was good enough for our specific cameras, but in general isn't great and the settings are difficult to tweak. Real time shadows from area lights is still an open research topic."
"The scattering contribution in the fog is limited to the same frustum and not physically correct either."
"Tube lights use a very cheap and practical solution to approximate area lights, but the resulting quality is much lower."
In other words, like all realtime solutions with current technology, they are "cheating" heavily.
That being said I recognize that the results can often look very good. The problem is they are not accurate or fully realistic. We aim for a higher standard of realism but yes, it does take longer. I do wish we had a better ability to find an in-between, with fast and reasonably realistic results, accepting some compromise. Right now the Terragen way is pretty much "max realism or nothing".
- Oshyan
I still think this is really an issue having to do with no real distance control, leaving luminance either having to be extremely bright, or it doesn't function at all (besides the surface being bright with no casting). If there was control of the distance light was being emitted from the surface, it would probably work fine. Using the surface displacement as vector alignment for light direction, or if none, just straight on the axis of the shape (like a sphere). When you look closely, light is working just as it should be, and is scattered via the cloud, but it's just probably a 10000x too bright, but with current setup, it's either too bright, or literally non-luminous. If you use a light source, and up all the settings to ridiculous extremes, you get the same result as a luminous surface with high luminosity.
Looking forward to some sort of solution to this as it's always been a limitation I recall for the last 10 years or so really. There are countless ideas I've had that are limited simply by the fact the only light sources are technically a light-ball, spotlight, and a fixed sun, and are completely reliant on user control. Nothing using a series of lights is possible without manually doing it, something that has been addressed in every rendering program I've used so far, including light arrays, which I guess would be populations in Terragen with the added ability of columns/rows as apposed to just random seed based. So far it all seems to be a simple process to incorporate in future versions to have light populations like the shader array + population, especially like the shader array as it's just instances and locations and the math done for the user instead of having to do all the calculations or positions.
Totally understand wanting to be realistic and not "cheating", but I feel the functionality is almost there, just needs to be refined. Though the option for "fake" realism never hurts. Similar to all the other fake options, stones, clouds, etc, and some of the fake options you just have to do to really achieve some things in TG. Just the ability to create relatively smooth luminous light itself may bring in a whole lot more professionals for cinematic use, as watching makings of on movies and world, they often incorporate planes with random lighting for the "Moth Effect" to attract audiences. And I don't mean the go-to lens flaring.