Daz light emitting primitives

[alexander3rd]

Played around with an indoor scene lighting a bit, and got a little confused. Have a look at the scene below:


It's illuminated with HDRI, multiple light emitting surfaces already bundled with the motorhome model, a spot light I added behind my model's hair (replacing the small plane in the screenshot, as I saw strange behavior when rendering it) and a primitive plane I modified to act like a big softbox, in front of the model.
Both the planes had to be hidden, leaving only the light emitted, so I searched around a bit and people suggest lowering the opacity to 0.0001. The problem with that, is that it lowers the light output, so there has to be a compensation. Moreso, why I replaced the backlight plane with a keylight - when rendering, the back plane left white pixels in it's place, guessing it has to do something with the opacity. Since the value of 0.0001 isn't exactly a 0, it's not entirely invisible.
Two questions, how would you guys light this kind of scene? And how do you hide an object properly, that is used only as a light emitter?
Thank you!

 

[DreamLab Studio]

I don't really have a specific answer but a suggestion. I use the Iray Ghost Light Kit:

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It makes it very easy to add invisible light panels in the scene that are easy to scale. They have always seemed to work without any issue for me.

After you place and size the red/black light panel you double click an option in the Content Library and it turns invisible. Then you can adjust the light temperature and amount.

The only problem I've had with it was it's so easy to add lights I went way overboard and added like 20 in one scene which was overkill. I'll just call it a learning experience.

 

[DreamLab Studio]

I forgot to mention the Iray Light Probe Kit which seems pretty interesting as well:

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it's not that different. I've only played with it for about 10 minutes one day but it seems very easy to use as well.

 

[alexander3rd]

Thanks, will check them out. Speaking about overkill, isn't so many lights in a scene like mine above overkill too? I'm satisfied with the look, but noticed faster render speed when both the HDRI and bundled emissive surface lights were off, leaving only the plane & spotlight. Of course if I needed to illuminate, say, the back of the coach, there would be another light - but either way not so many lights as in the scene.

 

[Volta]

One thing to take into account is more individual lights slow the render speed, more rays to trace, brighter lights speed up renders, or more accurately less shadowed areas speed the render since shadows are more complex to render, especially with more lights.

I've found good things happen when you keep the lighting simple, especially for portraits and close up work, for larger scenes having an overall directional light like sun-sky or HDRI is good, then adding scene specific lights, either in a three point system or in places where a scene would be providing light naturally, lamps, light bulbs, car head lights ect.with ghost lights, effectively an invisible plane or shape that glows, you can create your own by turning opacity way down on a plane or primitive and using Daz's inbuilt emissive shader on it, turning it into a giant glowing invisible surface, good for even light, just pop one over a window and away you go, since opacity is near 0 it doesn't block outside lights either or cast shadow.

Your right not to want too many lights, it complicates things where you don't need to, but at the same time if you want an evenly lit interior scene where you can't let the HDRI or similar do the heavy lifting it can be tough to get a realistic look rather than a studio type look.

If you're not familiar with photography go look up sickleyield's three point light system on deviant art, it helped me cut the number of lights down, just an adaptation of a photographic technique for use in daz really.

 

[Rich]

It's worth noting that emissive surfaces, like ghost lights, do tend to increase your render times. Unlike a spotlight, iRay doesn't "know" that it needs to look there for light, and so it kind of "finds it by accident," which tends to increase the time it takes for images to converge, since sometimes the rays it use to explore the space hit the emitter and sometimes they don't. (In the case of spotlights, iRay knows they're a light source, so it goes looking for them.)

That's not to say you shouldn't use them - sometimes they are far and away the best solution. But everything's a trade-off.

Also, when using emissive surfaces, you can change the units with which you specify the amount of light put out, which partially compensates for the "reducing opacity" problem. If you use "kcd" instead of "cd", (kilocandles instead of candles), you can divide the values by 1,000.

 

[alexander3rd]

I tried Mr_Batsu's ghost light kit recommendation, good stuff, it solves the problem with opacity. Still, of course, it's just an emissive surface. I'll compare an identical set of renders with multiple ghost lights vs multiple spotlights, will see if it's worth sticking to one or the other more often or not.
Maybe there's something similar to ghost lights out there, that Daz recognizes as a light object?

 

[Rich]

Maybe there's something similar to ghost lights out there, that Daz recognizes as a light object?

No, at least not at present. Essentially, ghost lights are a "trick" we play on iRay - the fact that a nearly transparent object can still emit significant light is a fortunate quirk.

Basically, iRay (or, at least, the Daz implementation of it) knows about "environment lights" (e.g. HDRI, sun/sky) and the four kinds of lights in the "Create" menu (point, linear point, spot and distant) and that's it.

 

[Volta]

I've actually found some scenes are quicker with emissives, perhaps it was due to the overall better lighting level in the scene cutting down on shadows.

Oddly i tend to have more trouble with HDRI's, they always seem too dim or too greyish, often opt for sun-sky instead which i think is lighter on rendering in terms of resources as well, though done right you can't dispute an HDRI's results.

 

[Minha Ninfeta]

If you like the shadows and lights but the scene too dark still, you can increase the exposure time from 1 to 2 and adjust to your liking. Something they taught us in Photographia but it works for rendering too!

 

[Rich]

Alternately, if the issue is the light level the HDRI is giving off, you can turn up the environment intensity.

 

[alexander3rd]

Lighting seems more or less covered to me, just have to experiment further. Thank you for the tips.
Tested out Daz 4.11 beta today, with it's updated version of iray. In all honesty, I think I have 3 options, if I want to get quality renders with quick render times - slap in a 1080Ti & call it a day; work on the scenes, removing everything not visible to the camera and not necessary for the visuals; move to Blender, since Eevee in 2.8 will be a fantastic tool even on lower-end hardware.
But Blender is another beast in comparison, anyone even using it for our purposes? Or is Daz just more suitable for posing models, with all the assets available?

 

[alexander3rd]

Here's a comparison of IRay vs Octane (standalone) in different settings -

IRay:

Octane direct lighting:

Octane path tracing:


Of course the materials are different and some settings from Daz .obj export do not transfer over to Octane, like the top model's hair color in this case. All that can be adjusted and I adjusted multiple materials in Octane to replicate my desired result, but that's another topic.
Lighting - samples required & render time.
Daz IRay render took around 10 minutes on mostly default settings.
Octane Direct lighting - the render time is blazing fast, obviously, but getting a good looking result can be tricky.
Path tracing - Somehow in my case here, it would take hours of rendering to reach IRay's quality. There's much more control in Octane to get a desired result in the least amount of time, but path tracing still takes a lot longer than Iray, even with Diffuse depth decreased. If Diffuse depth is set to 1, the speed increases drastically, but the result is comparable to Direct lighting.
As seen in the 2nd Octane render, it took 10 000 samples to get to a decent quality, minimizing the noise. The rest is 700 samples after rendering 10 minutes, and very noisy.
Maybe someone using Octane standalone here could give a few suggestions?

 

[OhWee]

Here's a comparison of IRay vs Octane (standalone) in different settings -

IRay:
View attachment 151163
Octane direct lighting:
View attachment 151164
Octane path tracing:
View attachment 151165

Of course the materials are different and some settings from Daz .obj export do not transfer over to Octane, like the top model's hair color in this case. All that can be adjusted and I adjusted multiple materials in Octane to replicate my desired result, but that's another topic.
Lighting - samples required & render time.
Daz IRay render took around 10 minutes on mostly default settings.
Octane Direct lighting - the render time is blazing fast, obviously, but getting a good looking result can be tricky.
Path tracing - Somehow in my case here, it would take hours of rendering to reach IRay's quality. There's much more control in Octane to get a desired result in the least amount of time, but path tracing still takes a lot longer than Iray, even with Diffuse depth decreased. If Diffuse depth is set to 1, the speed increases drastically, but the result is comparable to Direct lighting.
As seen in the 2nd Octane render, it took 10 000 samples to get to a decent quality, minimizing the noise. The rest is 700 samples after rendering 10 minutes, and very noisy.
Maybe someone using Octane standalone here could give a few suggestions?

Personally, I prefer the second one (Octane Direct Lighting). It's the most visually interesting to me.
Except for the blonde dye job of course!

If ODL, as you say, blazingly fast (an actual time result would be nice here if you have it), yeah that looks perfectly acceptable and if it results in a faster pipeline, yeah I'd be happy with that result.

Of course, if you are spending a lot of time replacing textures with ones suited to Octane, yeah you need to take that time into account, but if you are rendering say a animated sequence with a fairly large number of frames, it sounds like ODL would be the way to go when rendering longer animation sequences.

Too many people get hung up on perfect quality in their games, when 'good enough' is all they really need most of the time. If you are trying to win render contests, yeah then it might be a different story of course.

 

[alexander3rd]

Personally, I prefer the second one...

Thanks for the feedback.
If I had a 1080Ti or something even beefier in my system, I'd go for perfect quality too - my ego would not allow anything lower than 'almost perfect' But I am working with 1050Ti & 8gb ddr4. This gpu is good for decent 1080p gaming at most, not for raytracing or other things requiring a ton of cuda cores. Such hardware really forces you to have a different mindset about your works. I try to optimize the scenes as fast as I can, as much as I can. If there is something I can get rid of or decrease, I'll do that. If a specific light in the distance takes more render time, I'll either just make the surface illuminated, or turn off the light completely.
Yes, getting things to work from Daz to Octane takes some time. It doesn't take time with the Octane Daz plugin, I have a demo of it for testing and teasing lol. There, pretty much everything is converted automatically as soon as it's added to the scene, or changes are made.
Don't know about animations - if stills are done in Iray and animations in Octane, there will be a huge visual difference all of a sudden, inside the game. Some of it could be easily batch fixed in post, but if the maps and materials look different, hmm. Will have to test it out.
Speaking about Octane, version 4.0 will be a game changer with it's AI features. And they will release a free tier, though I don't know if it requires a previous full licence or not. Otherwise, it's either a monthly subscription, or a hefty purchase.

 

[alexander3rd]

Here's Miranda's Icecream Parlor, that I stripped down a bit because it was a test of patience in Daz to even move around, while it's texture shaded.
Maybe it doesn't look as fancy as in Iray, but imo, the 43 second render time is quite worth that tradeoff.