Overexposed, No Lights In Scene

plan111

Hi.

I attached a screenshot of a partially rendered image. There are no lights in the scene. I lowered both "Envieonment Intensity" and "Environment Map" in the Render Settings but they don't have any effect, the image is still to bright. Is there a setting somewhere or a global light I need to disable?

Thanks

SofaCitizen

If there are no light objects then I imagine that all the illumination is coming from emmisive surfaces in that indoor scene.

The easiest way to adjust would be to go into Tone Mapping and either decrease the cm^2 Factor or increase the Exposure value. Technically you can also adjust the three values inbetween but those are mostly linked and so sticking with those two will be simpler.

plan111

The cm2 helped a bit. Thanks. I miss be missing somethig though. Of all the environments I purchase that have both a "preload" and a "ready to render" scene, very rarely do they look even remotely like the pictures on Daz's site. Am I missing something?

SofaCitizen

Well, that could very well depend. Are these older environments? If they are made for 3Dlight then there may be some issues when they are auto-converted to Iray. However, I think more likely and something I have seen myself is if they relied heavily on ghost lights. Nvidia changed the way these worked quite considerably in a reasonably-recent update which effectively made them no longer work. Thus such environments started to appear way darker as a result in iray.

Although that won't be the case if you are seeing things over-exposed by default. Do you have any examples of such products and are they darker or lighter than the promo pics suggest?

plan111

Most of the time they're darker, sometimes brighter, like the example you saw. Just one last question: You talked about the lights being too emissive. When I select one of the images, in the "Surface" tab I have only two parameters: Emission Color and Emission Temperature. However, increasing or decreasing them doesn't change anything. Is that the place where we need to define the emission intensity? I'd guess so, but nothing happens.

SofaCitizen

Those are just the two parameters that have Emission in their name, so I assume you are doing a search for that? Instead click on the Emission section and you will either see one or 6 parameters. If there is only "Emission Color" and it is set to black then this means it's a surface that does not emmit light and so the remaining parameters are hidden as they are redundant. If you change the colour to something non-black then the surface will emit some light and so the other parameters will appear. If you are looking to change the brightness of that particular emissive surface then you should focus on the Luminance and Luminance Units. Although really you can leave the units as they are and just adjust the Luminance up or down depending on if you want it brighter or duller.

Pay attention to the values since if you are adjusting them up and down and not seeing any change then it's likely that you are not adjusting them enough and/or are not looking at the correct surface. For instance, the default value for Luminance is 1,500 and the plus/minus buttons change this by 50. This is unlikely to make a massive difference so you may need to try manually increasing or decreasing by a few thousand or even a factor of ten - e.g. going up to 5,000 or even 15,000. That way you are more likely to see a noticable change.

However, when the entire environment is uniformly darker or lighter than desired it's best to tweak the Tone Mapping settings so that you only do it once rather than over and over for each emissive surface.

Elor

Another possibility: if you're using a recent version of Daz Studio (a recent beta for Daz 4.22 or the last release, Daz 4.23), Daz changed the default value for Burn Highlights and Crush Black in Tonemapper Options (before, they were set at 0.25 and 0.2, now they are at 1 and 0 (it was done to get Iray closer to Filament, I suppose in preparation for Fila-toon)) which will change how a scene look (at least with scenes created with a version with these changes active: they should not apply retro-actively).

Plant

could be the camera headlamp

SofaCitizen

Elor said:

Another possibility: if you're using a recent version of Daz Studio (a recent beta for Daz 4.22 or the last release, Daz 4.23), Daz changed the default value for Burn Highlights and Crush Black in Tonemapper Options (before, they were set at 0.25 and 0.2, now they are at 1 and 0 (it was done to get Iray closer to Filament, I suppose in preparation for Fila-toon)) which will change how a scene look (at least with scenes created with a version with these changes active: they should not apply retro-actively).

Oh! Is that why it happened? I thought I'd accidentally messed something up when I noticed that :/  I guess I need to pay more attention to the changelogs!

plan111

SofaCitizen said:

Those are just the two parameters that have Emission in their name, so I assume you are doing a search for that? Instead click on the Emission section and you will either see one or 6 parameters. If there is only "Emission Color" and it is set to black then this means it's a surface that does not emmit light and so the remaining parameters are hidden as they are redundant. If you change the colour to something non-black then the surface will emit some light and so the other parameters will appear. If you are looking to change the brightness of that particular emissive surface then you should focus on the Luminance and Luminance Units. Although really you can leave the units as they are and just adjust the Luminance up or down depending on if you want it brighter or duller.

Pay attention to the values since if you are adjusting them up and down and not seeing any change then it's likely that you are not adjusting them enough and/or are not looking at the correct surface. For instance, the default value for Luminance is 1,500 and the plus/minus buttons change this by 50. This is unlikely to make a massive difference so you may need to try manually increasing or decreasing by a few thousand or even a factor of ten - e.g. going up to 5,000 or even 15,000. That way you are more likely to see a noticable change.

However, when the entire environment is uniformly darker or lighter than desired it's best to tweak the Tone Mapping settings so that you only do it once rather than over and over for each emissive surface.

Yes, that's what I was doing, searching for emission. I don't see any "emission" section though. Is it in the surfaces tab?

Here's a screenshot of my surface tab. I suppose "Screen 2" would be the one emitting the light.

 

SofaCitizen

plan111 said:

Yes, that's what I was doing, searching for emission. I don't see any "emission" section though. Is it in the surfaces tab?

Here's a screenshot of my surface tab. I suppose "Screen 2" would be the one emitting the light.

Expand the "Screen2" section and you'll see the sections under it. However, while you have the whole of Section2 selected you have now scrolled down to the relevant parameters anyway.

plan111

Aaaah. There you go. Thanks SofaCitizen and everydody.

Elor

SofaCitizen said:

Oh! Is that why it happened? I thought I'd accidentally messed something up when I noticed that :/  I guess I need to pay more attention to the changelogs!

Initially, I thought it was just one those time when Iray preview decided to misbehave on my Mac but at one point, my brain started to work and I saw that it was only happening with the beta version. So I went searching for an answer inside the changelog