Daz Mystery reflections

[Nicke]

Hey, folks.

So, I was making an animation and noticed the light changing wildly between frames, and upon investigation it turns out that it's reflections that changed a lot, or it seems like that anyway.

Like so:

Spoiler: two images

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These are not two different frames. This is in perspective mode, nvidia iray. All I'm doing between the two screenshots is literally rolling my mousewheel one click to zoom in/out. It's 100% reproducible.

What changes are reflections (maybe?), it's most visible with the light coming in through the windows, but it affects all surfaces.

What I've tried:
- Removing all other light sources in the scene. Makes no difference.
- Rotate the HDRI and changing its values and so on. Makes no difference.
- Tried a new camera. It is the same with different cameras and in perspective mode. If I find the right distance/angle, just tweaking it back and forth causes this effect.
- Changing window opacity to 0 had some effect on the floor, but other reflective surfaces are still messed up.

Am I missing something obvious?

 

[Nicke]

It's definitely not only reflections. Just moving the camera a tiny bit causes this difference in the hair:

Spoiler: hair

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The upper looks correct while the lower looks like I don't know what. There's no changes between these two pictures at all on my side except a small movement of the camera.

 

[Zargon_games]

The first thing I would advise you is not to be totally guided by what the Iray preview shows you, it can have differences with the final render, especially if you use ghostlights.

Then, what strikes me the most is the difference of exterior light between frame and frame. How are you lighting that? Check if you don't have by chance dome rotation between frame and frame. Or in case it is an exterior spotlight, if you don't have it grouped to the camera and you are moving it.

Lastly, why so many pointlights? I would remove those around the figure and light it in another way, try if removing them doesn't solve your problem.

 

[Nicke]

The first thing I would advise you is not to be totally guided by what the Iray preview shows you, it can have differences with the final render, especially if you use ghostlights.

Then, what strikes me the most is the difference of exterior light between frame and frame. How are you lighting that? Check if you don't have by chance dome rotation between frame and frame. Or in case it is an exterior spotlight, if you don't have it grouped to the camera and you are moving it.

Lastly, why so many pointlights? I would remove those around the figure and light it in another way, try if removing them doesn't solve your problem.

I first noticed it in the frame by frame rendered animation. It's consistently weird no matter how I view it and no matter if I render or preview the scene, camera or no camera

The exterior is a HDRI. Just to be clear, the top two pictures with very different lighting is NOT two different frames in an animation. They are exactly the same frame, where I just touched the mousewheel one click to move the camera slightly closer.

The main lighting of the scene is 3-point spotlights. There's some ghostlights around the room. The four pointlights are very weak, and there because I wanted a little more lighting down there. It's a 576 frames animation where the camera rotates and zooms.

I've tried eliminating all the lights and nothing fixes it. There's other oddities than just how much light comes through the windows. The pool area itself is completely different between the two images for example.

 

[Nicke]

Here's another thing, frame 14 and 15. I've gone through all the surfaces on the hair, nothing changes. What can even cause this? Man, I'm stumped. Tried deleting thing after thing in the scene to see if anything has any effect, nope.

Spoiler: frame14

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Spoiler: frame15

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EDIT: But when I move the camera closer on frame 15, the weirdness with the hair goes away.

 

[Zargon_games]

To be honest, I've never had anything like this happen to me, it's a very unusual problem. It has to be something in the lighting or something is wrong in your render settings. I would try the following to rule out possible causes:

1 - Set the render settings to their default values.

2 - I would try to make the same render only with a single light source and deleting all the others, to rule that out.

3 - are you using camera with cutout planes? try not using that, in certain occasions they cause quite strange errors.

 

[Nicke]

To be honest, I've never had anything like this happen to me, it's a very unusual problem. It has to be something in the lighting or something is wrong in your render settings. I would try the following to rule out possible causes:

1 - Set the render settings to their default values.

2 - I would try to make the same render only with a single light source and deleting all the others, to rule that out.

3 - are you using camera with cutout planes? try not using that, in certain occasions they cause quite strange errors.

1. Default values makes makes no difference.
2. I'll attach a render below with all lights turned off, replaced by one strong light.
3. Nope.

So in the image below, the difference between them is that I zoom in the camera minimally, and suddenly it's fine.

I've deleted almost everything from the scene, still experimenting.

Spoiler: image

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[Nicke]

Okay, I kind of, sort of, solved it. If I change the opacity of the glass ceiling to 0, the problem with the hair seems to go away. Can't find any surface settings on the glass that fixes it though, so no idea why. No idea why it'd have that kind of impact anyhow, no matter if any light through the glass even hits the character (though some reflected light would I guess).

Weirdest Daz error I've ever had. Not sure if it's fixed for real either until I get a hundred frames in or something.

 

[Saki_Sliz]

Okay, I kind of, sort of, solved it. If I change the opacity of the glass ceiling to 0, the problem with the hair seems to go away. Can't find any surface settings on the glass that fixes it though, so no idea why. No idea why it'd have that kind of impact anyhow, no matter if any light through the glass even hits the character (though some reflected light would I guess).

Weirdest Daz error I've ever had. Not sure if it's fixed for real either until I get a hundred frames in or something.

Actually, I might know what that is.

I use blender mostly, but you are able to create something similar. With blender, you can set the amount of light bounces. more importantly, you can set the amount of light bounces per type of object.
These are my preferred setting, low enough to run fast, but enough bounces to allow for ambient occlution, global illumination, and to make the lights a tad bit warm and soft.

Notice that there is a Transparency section, and that its the highest. Pretty much what happens is light does not bounce through transparent object, but it still counts as a collision, so it is considered a bounce. Transparencies have to be higher otherwise transparent objects start to look dark, and I found 12 was the minimum in order to notice no reduction in quality. Transparency not only affects glass, but anything that uses opacity/alpha, such as hair. In fact, if I'm using daz hair assets, I often have to crank up the transparency count (and thus the total) up to 30 or 50 just so that all the different layers of hair render correctly, else it fails and you get what you saw in your pictures.

it may be a preview setting, or it might be that you need to increase the amount of light bounces in your render. the glass worked because i notice Daz optimizes things, and 0 opacity it simply removes the item from the rendering, thus it looks fixed but really your just delaying the issue. What I can't explain is why it applies to everything at once, all teh hair at once, or all the window at once. With blender, its per light ray, so it just ends up making things darker as less and less light gets through.

 

[Nicke]

it may be a preview setting, or it might be that you need to increase the amount of light bounces in your render. the glass worked because i notice Daz optimizes things, and 0 opacity it simply removes the item from the rendering, thus it looks fixed but really your just delaying the issue. What I can't explain is why it applies to everything at once, all teh hair at once, or all the window at once. With blender, its per light ray, so it just ends up making things darker as less and less light gets through.

It doesn't quite explain why i twitch the camera a little bit and it's good again. But I'm leaning towards all the glass in the room (windows and ceiling glass) "help" in causing things to happen. I've used the products in plenty of scenes before, both the room, and the hair and so on. Never noticed anything, and I wouldn't now either if I hadn't done an animation where the camera moves around. From the front it was all peachy.

I'd investigate further but shit, I spent half a day on it already, the animation will take 20 hours to render, and I got deadlines

 

[Alcahest]

Have you tried turning the computer off and on again?