An initial attempt to improve my previous render:
Aside from the colour problem that I described, I was much disappointed with the previous render result because I felt it to be a huge step backward in terms of realism. So I set out to identify the problem and here's what I found so far. I know that there are quite a few people on CF who are interested in 3D artwork. So I'm going to share some of the things that I found for those who are still learning it like myself:
The Lighting
I heard people say that it is the lighting that can make or break a render and now I think I understand what they meant. The biggest problem with the previous render turned out to be an inadequate lighting setup. Probably there could be some remaining problems with the current lighting but I think it's a huge improvement over the previous one.
The most glaring errour was with an additional light source I added in front of the character which erased much of the skin details and made the overall render look flat. I did it because the area between the legs looked way too dark. But adding an arbitrary light source that doesn't correspond to a physical counterpart (e.g. a lamp object hanging on the beam) can give an impression that the scene is fake.
And more importantly, it's the contrast between light and shadow, or glossy and dry areas that reveals such details. So, when you try to make everything bright, you will lose much of such details. I didn't know that before so it was the biggest lesson I learned from fixing this render.
It was difficult to resist an urge to show off some of the models and textures on which I've spent much time and effort. For example, I know that the details on the boots can be quite impressive if I put more light on them. But now I understand that I should accept the fact that I must sacrifice some details to make more important ones to stand out.
The Angle
Although I found out that it was the extra light source which was causing such a problem, I couldn't figure out how to fix it properly. I tried to put more lamps or max out exposure but it only made the scene even more unrealistic.
Out of frustration, I began to move the characters around until I hit a certain spot which immediately improved the lighting by quite a large margin. Now, not only the problem with the shady area between the legs was fixed, but also this particular camera angle gave the outline of my character very nice highlited area, restoring some of the details lost in the previous setup. It also made the depth of field effect more prominent, as you can see from the right side of the image.
In short, I learned that sometimes a lighting problem can be fixed by simply moving or rotating things around until they hit the right spot.
Branching Path Tracing
As a beginner of 3D art, there are a lot of things still that I don't understand, and the path integrator option on Blender was one of such things. After I switched to Filmic tone mapper (Filmic Blender, to be specific) and physically based light presets (Extra Lights Blender addon), I had much trouble with making the lights sufficiently bright for the scene. I couldn't just crank up the gamma or brightness as it would be defeating the purpose of using such a setup.
I still don't understand the root cause of this problem, but switching to BPT at least mitigated the problem much, as well as enhancing other aspects of the render at the cost of increased render time.
The current image is a result of almost 8 hours of rendering but it still shows a lot of 'fireflies' as you can see it above. But at least I have a good idea of what settings I should try to tweak to fix that problem. And Blender provides an AI based denoise feature, which I would have applied to the image had Blender not crashed shortly after when the rendering was done.
Textures
I suspected it could be the dirt and whipmarks texture that I created with my insufficient skills that made the previous render look so dull. So, I rendered without that layer to confirm my suspicion and it turned out I was right about it. While hiding much of the skin details, it didn't provide interesting details of its own. So, learning how to create an alternative dirt/whipmarks texture without such a problem will be my next immediate goal in this project.
On a side note, I also changed the texture on the pants of the overseer. Previously, I mistakenly turned off the normal channel on Substance Painter so it looked a bit less realistic. And I changed the colour to orange, to make the overseer resemble a garbage worker, because those slaves in my setting are treated that way.
I know that the pants still don't look too realistic. But it can be mitigated later by adding some believable wrinkles. It's just that I've been too lazy to spend enough time to enhance that part but I'll do that eventually. I just wish I knew there's a much better way to create clothes in Blender before I started working on the model. Maybe I'll rework them later, especially in case I may decide to make a movie clip with those assets.
Things like clothes or fluid sims are one of the few advantages of using Blender instead of Daz Studio for such an artwork, so I better try to exploit the fact.
Pixel Filter
I also did an experiment with pixel filter setting by giving the pixel width a very low value (1px). It certainly made the skin bumps more noticeable, but probably it was a bit too much as you can see from the harsh looking areas on the shins or from the jagged hair strands. I'll go with a slightly higher value the next time and see what happens.
Hardware
As I mentioned above, it took 8 hours to achieve that result. Probably I could optimize the settings further, but now I feel that I'm literally trading off the lifespan of my graphic card for those renders. When the render process is running, the whole computer becomes almost unusable and I can even smell something burning. Probably I should consider renting a render farm for final renders. That way, it may even be possible to make short movie clips not just static images while avoiding burning out my graphic card too soon.
Monitor Calibration
As mentioned in my previous posts, I found that my desktop monitor shows images in quite different colours than what my other laptop or iPad does. To solve the problem, I learned how to install a correct colour profile and calibrate my monitor.
Unfortunately, it turned out that it wasn't sufficient to really fix the problem and I'm still having much difficulty in making my textures or renders to show up in other devices as I intended.
I suppose there's no remedy because my monitor is a cheap one. I didn't intend to do any serious art related works when I purchased it and I'm quite poor to spend much on hardwares if it's not absolutely necessary.
So, I just gave up on this problem and decided to take the final render to my laptop to perform some colour correction before posting them here. It's not a perfect solution, but I can't think of anything better at the moment.
Final Words
What I wrote above wasn't intended to serve as advices from an 3D expert since I'm clearly a beginner still. It's just that I'm vastly enjoying the learning process and want to share some of the progress I made along the journey.
As mentioned above, my next goal would be finding out how to create better dirt/whipmarks textures and I'll probably start working on it soon. But probably I better give some love to my story thread before that, since I haven't written anything for couple of weeks because I've been too engaged with this 3D project.
