Emissive color changes when I increase intensity

[kenzan_tsutakawachinn]

I'm working on rendering a light which uses COB LED.
The physical example is in screen shot 1.
I've increased the intensity of the lights to work well in the scene, but I also want the light itself to look the correct color.

Looking at the second screen shot, the material is EMITTING the right color but the NURB/BREP is not showing the right color, its essentially over exposed.

How do I get the geometry to look the same color as the emitted light?

Thanks.

[Micha]

If your intensity is to bright than the color burn out. Lower the intensity or use a lower burn (exposure option at the frame buffer or global color management option) or filmic tonemap from the framebuffer.

[kenzan_tsutakawachinn]

Thanks
I've messed around with the exposure, and lowering it, gets me the color on the BREP but now I'm not getting enough green light to shine on the rest of the scene.
Should I duplicate the the BREP and use one for area light and one for the color of the BREP itself?

[Micha]

Yes, it's like in the real world, an LED light that illuminates the surroundings is itself heavily overexposed and only good cameras with HDR algorithms manage to capture the dynamics to some extent.

Sometimes it helps to use the frame buffer lens effects and create a nice glow effect that makes the color of the emitter a little more visible.

But I often hide real lights behind large-area emitters like an area light. To do this, I deactivate “affect shadow” in the emitter material. Two emitters with a distance between them could also work if you assign them different materials and visibilities. Without spacing, I could imagine that the calculation would have problems, but maybe that works too.

What shape is your light object?

[piotrus3333]

It is all about the view transform. Swap filmic tonemapper to something better:
https://forums.chaos.com/forum/chaos...24#post1224224

try filmlook01 or AgX first.

[Micha]

Yes, a well-tuned color mapping similar to human vision would probably be the best. But it's not always easy because contrasts can quickly get lost.

For photos, I like to use Adobe Camera Raw with fine-tuning for the important aspects of an image. It delivers impressive results. It would be great if the VFB could use ACR.

I will give your suggestions a try, thank you very much.

For the future: wouldn't it generally be best if you could try out the color mapping in the frame buffer, but then define it in the Color Management options so that the sampling is based on it when calculating the image?

[Peter.Chaushev]

Hi kenzan_tsutakawachinn,

When you use an Emissive material with "compensate EV" enabled the color you pick will appear with the exact same value in the rendered image as long as you have set the intensity to 1.
If you increase the intensity to 2, the RGB values of the color will appear twice as big in the rendered image, and so on.
You can test this by comparing the color value (Color Space: Rendering) of the material and that of its render appearance (hover over it in the VFB).

One option you have is to use a material intensity value and camera EV to produce an output that feels ok.
Alternatively, set the material intensity to 1, and then also add an invisible light source with the same color and position that provides more substantial illumination to the scene.

Hope this helps!