Daz Shadows on the floor in Daz Studio

[The Rogue Trader]

Hello, it's been a while since I noticed that shadows on floors (not the Ground) behave quite erratically for me. I looked around and I don't see people complaining, so I must be systematically doing something wrong.
Basically, the characters that I render (V4, G1, G2 or G8: it doesn't matter) most often do not cast shadows on the floor of the various environments they are in, or if they do, it's very very faint and short. They usually cast shadows on other objects or characters, and always over themselves, but almost never on the floor. It happens in very different lighting systems.
Some examples:

HDR light (the room has no walls) and an emissive plane above. I reworked this particular setup over and over because I couldn't get any shadows at all or the lighting was unbelievable for an indoor room.






12 emissive surfaces and 3 spotlights (point light).
Just out of the oven: notice that onlythe naked guy cas a shadow at all. I waxed the floor so it wouldn't be too evident. Until the last-second adjustment (I raised the 3 spotlights form 250-300 to 400-500 cd/m2) no character did cast shadows on the ground.



Same emissive lights, but the 3 spotlights are in different positions.
The shadows are all over the place and I don't get any sense from them. The giant doesn't seem to be casting any on the floor (maybe on the wall).
Also, the floor stopped being reflective?



Ghost lights on the candelabra and one spotlight on the far right. Like all the other spotlights, it comes from the above,.
Notice that the bucket casts a nice dark shadow, but not the guy near it.

What I'm doing wrong?

 

[Domiek]

Hard to say without seeing the size, position and strength of your lights.

Do you use giant emissive planes from above?

 

[The Rogue Trader]

Hard to say without seeing the size, position and strength of your lights.

Do you use giant emissive planes from above?

In the first one (the one with the three girls in the library) there's a plane from above to simulate electric lighting. Not giant, IIRC 1mx1m (it's been months since I last opened that file and I can't do it now because I'm rendering). I can't remember its strength, but surely it isn't in the millions of lumens.

The fantasy ones use only point spotlights because I want harder shadows. All range between 3-500 cd/m2 lumens for the closer (2-3m) ones and 1000 cd/m2 lumens for the further ones (across the room, I guess about 5-6m).
Emissives and ghostlights are in the same luminosity range too: their purpose is just to make the background visible, not to light the characters.

EDIT: I checked and the spotlight measurements are in lumens (only emissives and ghostlights are in candles for square meter)

 

[The Rogue Trader]

I use Iray... My problems happen with both "Dome and scene" and "Scene only" environments.
I think "Draw ground" is constantly turned off. Wouldn't it interfere with the floor?
EDIT: I did some quick experiments with "Draw Ground" turned on (ground shadow = 1.0) and if the floor is above the ground, unsurprisingly, the situation doesn't change. If the ground is above the floor it interferes (but still no shadows).

 

[Domiek]

In the first one (the one with the three girls in the library) there's a plane from above to simulate electric lighting. Not giant, IIRC 1mx1m (it's been months since I last opened that file and I can't do it now because I'm rendering). I can't remember its strength, but surely it isn't in the millions of lumens.

The fantasy ones use only point spotlights because I want harder shadows. All range between 3-500 cd/m2 for the closer (2-3m) ones and 1000 cd/m2 for the further ones (across the room, I guess about 5-6m).
Emissives and ghostlights are in the same luminosity range too: their purpose is just to make the background visible, not to light the characters.

Seems to be working fine.



With only 1 light source, there's clear shadows cast onto the ground from the figure.

Bringing up the environment light back to full strength removes these shadows since the environment light is much stronger than this single plane.



Increasing the plane to some ridiculous number makes it dominant and cast shadow once again.



Lighting needs to be very intentional. Often time, people throw in a bunch of lights just to brighten up a scene and then have a headache trying to figure out which direction to take it in. Shadows are dependent on light strength and size in relation to each other. It's best to get this dynamic as close to your desired goal as possible and then adjust overall scene brightness by adjusting the exposure value for the scene.

 

[The Rogue Trader]

Bringing up the environment light back to full strength removes these shadows since the environment light is much stronger than this single plane.

Wait, what...

I see: adding a stronger light doesn't add its (darker) shadows to the existing one, but replaces it.
Quick test:

I killed all the emissive and let only one (point) spotlight, 5000 lumens (instead of the previous 1000), 3m away.
Shadows on the ground.
Good, that's the right track.

Turned on the other two (point) spotlights, but left them at 800 and 400 lumens, about 2-3m away from the figures.
The only shadows come from the 5k spotlights.
And...

Shot all three spotlights to 5k lumens, everything else unchanged.
The figures gain shadows from all three lights. Because no light drowns the others.

That's not the effect I was looking for, but I can build on what you taught me today to find a decent style. Thanks, you've been a real eye-opener!!

(Also, dazzlingly faster renders. Weird, since until now using spotlights slowed down my renders).

 

[Domiek]

Wait, what...

I see: adding a stronger light doesn't add its (darker) shadows to the existing one, but replaces it.
Quick test:

It's not so much that it replaces it but the dominant lights shadows become more prominent. The other light just ends up illuminating the area more. You can test this out for yourself.



Adding a large but weaker light source lightens up the area where the shadow is cast but the shadow is still there.



Increasing the power of the weaker light continues to further illuminating that area while the original shadow is still distinctly visible.



Increasing the size of the original small powerful light source without adjusting the power softens up the shadow.



Making it giant pretty much eliminates any interesting shadows.



This is usually what happens with most newer devs. They throw giant mesh lights to illuminate the scene which ends up destroying most of the interesting light dynamics resulting in flat lighting.

Take a look at 3D lighting tutorials on Youtube, there are so many. Whether it's Daz, Blender or any other software, the principles are all the same. It just takes a few days of really focusing and experimenting with light to get a good grasp for it.

In the Fall of 2020, I decided to dedicate a week to just experimenting with lighting. I'd find a reference photo and spend a couple days trying to recreate the light just to get a better grasp of it. I'm by no means an expert now but that week of exercises made me really comfortable with lighting whereas before it was just all just a guessing game.

These are some of those renders from that week.


This one had like 6 smaller light sources angled around her body to get those highlights.



Tried to do a low-light candlelit scene. The candle flames themselves suck and the water looks like tar but it still feels like it's solely lit by the candles despite most of the light coming from several mesh lights off-screen.



This exercise was an attempt to retain some shadows while still having highlights despite a bright well lit room. It came out kind of shitty but was still good practice.

View attachment 1999461
Shot all three spotlights to 5k lumens, everything else unchanged.
The figures gain shadows from all three lights. Because no light drowns the others.

That's not the effect I was looking for, but I can build on what you taught me today to find a decent style. Thanks, you've been a real eye-opener!!

(Also, dazzlingly faster renders. Weird, since until now using spotlights slowed down my renders).

Hell yeah, looking so much better already!

 

[The Rogue Trader]

This is usually what happens with most newer devs. They throw giant mesh lights to illuminate the scene which ends up destroying most of the interesting light dynamics resulting in flat lighting.

From what I'm understanding, my issue is exactly the opposite: by having several indecisive small lights of about the same power coming from different positions, they end up cancelling each other. Stepping on each other's shadows, in a sense.
Yesterday I made one last experiment, this time I let it render fully: it went literally 10x faster than when I had the mesh lights imitating candles.

Only two spotlights (I removed one, but I kept the other two at the same positions).
- 3m on the left: square 50x50 cm; spread 90°; 6000 lumens;
- Near the camera: circle 30cm wide; spread 90°; 800 lumens.

I've lots of experiments to do before I'll fully understand what's happening at the left of the screen, but I think I'm getting the general idea.
Of course, strong spotlights and reflective surfaces like metals are often incompatible. Close walls are a problem too. I'll have to think my scenes around these facts, instead of trying to hack the lighting around poorly designed locations.