Hi Michael,
I don't mind answering very specific questions
Actually, rendertimes are always very specific for every scene, that's why.
As usual you can take it almost anywhere you like.
I rendered this at 2400x1920 resolution and it took 8 hours I believe. I used AA8 with stringent adaptive sampling and detail is 0.75.
Furthermore I use increased ray detail multiplier for underwater detail/refractions and to reduce the dependency of GI on the detail setting slider.
As you may know the ray detail multiplier is set to 0.25 default. With detail set to 1 in the renderer that means that under water features are rendered at 1 x 0.25 = @ detail 0.25.
This also accounts for GI rays.
Increasing the detail slider in the renderer will increase the # GI rays (dots in the GI pass).
Increasing the ray detail multiplier will also increase the number of GI rays.
*Basically the #GI rays = detail x ray detail multiplier x GI relative detail.*
Just render the default scene and compare the number of dots in the GI pass when you increase the multiplier to 1.
Do the same with the default scene, but instead of increasing the ray detail multiplier to 1 increase the detail level to 1.
This should look the same.
Anyway, I rendered this in two steps:
1) Water disabled and GI 4/4/4, no surface details. I needed this to get detail in the lighting under the leafs of those ferns/palms onto the grasses/mosses.
2) Water enabled and GI 2/4/6, no surface details. I needed this to have the water render considerably faster. Logically, I only rendered a crop of the image to only render the water and I used some ray detail region padding to make sure that surfaces outside the cropped area were also accounted for in reflections and shadows.
3) Combine the two in PS.
An interesting approach is to not render this with GI 4/4/4 initially, but double the resolution and use GI 2/4/6. I haven't investigated yet which is really faster and/or which one is more memory conserving, but to get detailed lighting in tiny areas of screenspace you can choose to increase render resolution and use a lower GI sample density (GI relative detail that is and is the same as GI rays).
If I would render this image at 1k tall/wide and GI at more normal settings like GI 2/4/8 then this takes about 1 hour on my 2600K with 16GB RAM.
I could talk for hours about how to achieve realistic images, but it's also in the eye of the beholder.
Ryan (RArcher) renders from a photographers perspective and the lighting in his scenes is more esthetic and approaches the way a camera would capture it more than my usual work.
Frank (FrankB) uses different shading colours and lighting than me. Consequently he creates realistic images with sometimes huge contrasts.
Something hard for me to as I have another philosophy/approach.
I work from the perspective of how I would see it with my bare eyes. That would mean that in one image I'd like to have detail in shadows of surfaces as well as detail in shadows of atmosphere. With a digital camera that's not possible in a single shot, unless you resort to HDR solutions.
It's a challenging way of working and I admit it's definitely not the best and most realistic one in terms of how a real camera would capture it.
Basically my advice for realistic work is:
1) lighting: I pay attention to my shadow/direct lighting ratio in my images and how I can use it to emphasize aspects of my image I find interesting. In this situation the lighting direction offers enough shadows in the vegetation but also silhouettes a significant part of the rock.
Lately I really have the tendency to have >50% of the image space in shadow while the vast majority of work you see out here uses the opposite.
2) consequently to #1 you need good lighting and either need to use good GI settings or high resolution rendering as another approach to catch detail in the lighting. See above.
3) use decent AA for your objects. Either use AA6 with full sampling or AA8 with adaptive sampling and noise threshold to around 0.03. AA6 full sampling is almost as good, mostly eerie similar to AA8, but definitely faster.
4) Be gentle with everything: colour-contrasts (I made a mistake here which Jon/Hetzen perfectly pointed out) and contrast in displacement.
The strata shader here has plateau steepness and builtup values of <0.1!
There's also quite some voronoi involved, but not that much visible directly. I think/hope at least!
5) probably more, when it comes to my mind I'll post about it...
I'd say my weakest points of my work is that I have no photographers eye when it comes to TG2 and that I find it hard to sell a picture.
To make an interesting render or photograph you need some central subject or something particularly interesting.
Mostly my shots are just shots of a nicely built scene, but with no specific point of interest or grand breathtaking vista.
