Path tracing effects not as profound as I'd expect

Started by N-drju, September 04, 2019, 12:26:22 pm

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N-drju

I need to consult the issue of path-tracing with you.

I can't shake the feeling that any path-traced shadows I make, are simply too shallow compared to some of the other people's work. Here is an example of my dabblings. As you can see, the difference is barely visible:

pt.png

And before you ask...

Yes, the light source is hanging relatively low (19 degs over the horizon).

Yes, I did switch to "Exaggerate surface details" while disabling "Standard renderer" at the same time.

No, I did not increase GI settings in any significant way.

I just don't understand what else needs to be done to achieve the shadow depth and profound surface details that other, similar renders have. If you could, please tell me how I could tweak the settings. Or at least, provide some "rules of thumb" regarding the usage of PT in rendering.
"This year - a factory of semiconductors. Next year - a factory of whole conductors!"

Tangled-Universe

Low sun angles are usually no problem, some of my renders have sun at or even slightly below the horizon.
This is so dark that there's barely any light to bounce around I'd say.
The trees are near black and foreground atmosphere density is low, so speaking of "shadow depth" in this respect, there is none.
If you mean detail underneath and in the trees, that's really dependent on the amount of light initially pumped into the scene vs the albedo/brightness of the surface.
Light interaction with surfaces is multiplicative, so too dark surfaces will quickly quench out all the light present in your scene.
This holds true for both standard render and path tracing, the same general principles apply.

Atmosphere looks quite tweaked too, how does it look with default atmosphere?

N-drju

Hm, okay - I'll use your own work as an example. I mean the images found below which, not coincidentally, made me ask for assistance:

https://planetside.co.uk/forums/index.php/topic,25767.msg255526.html#msg255526

I might be wrong, but the first plane in your image also doesn't seem to have that much direct or bounced light. Yet, the shadow depth and resolution is stunning.

What do you mean by low atmo density in the foreground?

The surface is indeed rather dark, but I need it that way. If I make it brighter, I would probably end up with a rather unnatural effect, so I don't know how I could avoid it...
"This year - a factory of semiconductors. Next year - a factory of whole conductors!"

archonforest

I think the reason you don't see the difference is the darkness. I did path traced a forest of mine and the difference was pretty visible. I had more light though.
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Tangled-Universe

To be honest I don't really like my own result that much either, but it's indeed technically a bit better, but here's why probably...
You say you need it this dark, but that's not a reason to make your shaders ultra-dark.
So you can do either two things: brighten up your shaders a tad to give the path tracer something to work with, or, increase camera exposure.

N-drju

Quote from: Tangled-Universe on September 04, 2019, 02:07:08 pmTo be honest I don't really like my own result that much either, but it's indeed technically a bit better

"A bit". :P It's a textbook of how it should be done.

Here's another example with some rather dramatic changes - surface is completely white, default atmosphere. I also ticked soft shadows and it greatly changes the outcome too. Still not satisfied though. I don't know what to think about it...

ElrioPT2.png

These are literally my first two, three goes at path tracing, so I sort of accept that I might be ignorant on how it works and what to use. But still - it is rather depressing.

I am also quite appalled at all the noise that PT produces. Why? For what reason?! Uhhhh...

What (from the PT point of view) adds to the problem is that I really like the atmosphere tweaks that I use in the "El Rio" project. In fact, I also like the shadow direction and the size of the shaded area.

With that being said - is there no possibility at all to salvage this render into PT-worthy?
"This year - a factory of semiconductors. Next year - a factory of whole conductors!"

Tangled-Universe

Of course it can be salvaged!

Can you export the whole project using the gather project function in the file menu, then zip it and send it to me? m_huisman at hotmail.com 

I'm pretty sure this can be fixed.

N-drju

Quote from: Tangled-Universe on September 04, 2019, 04:16:56 pmOf course it can be salvaged!

Can you export the whole project using the gather project function in the file menu, then zip it and send it to me? m_huisman at hotmail.com

I'm pretty sure this can be fixed.

Sure can. :) Thank you for taking the time and offering an assistance like this!

If you don't mind, I'll send it tomorrow evening at earliest as I am somewhat busy tomorrow. And in a simplified version too, but with all features crucial to the problem.


By the way, here is another iteration. Brighter than the last one, and with less noise after I have read that AA can fix it:

ElrioPT2.png
"This year - a factory of semiconductors. Next year - a factory of whole conductors!"

Tangled-Universe

Quote from: N-drju on September 04, 2019, 05:03:27 pm
If you don't mind, I'll send it tomorrow evening at earliest as I am somewhat busy tomorrow. And in a simplified version too, but with all features crucial to the problem.


Sure, take your time. Just send it as is, without modifications please.
I have suspicions about the issue, but may miss the cause if I'm wrong and you modified certain parts.

N-drju

All I wanted to cut are the fake stone layers so it can render a bit quicker. Also, there is quite a mess in the shader section, as I got a little "trigger happy" with some (ineffectively placed) blue nodes. Wanted to clear that up and just translate it into PF sets. So you advise against it?

If you have an idea, then also have a look at this project pre-vegetation. Not sure if it lets you gather any evidence, but here it is:

https://planetside.co.uk/forums/index.php/topic,26529.msg268822.html#msg268822
"This year - a factory of semiconductors. Next year - a factory of whole conductors!"

N-drju

By the way, I got an idea myself - as stated in my topic, I cranked the refraction and reflection index down. That possibly means that by now, the river absorbs light rather than reflect / bounce it back. Hmm... ???
"This year - a factory of semiconductors. Next year - a factory of whole conductors!"