Background illumination

[EddyMI3D]

Hi there!

For a lot of my renders I like to use illumination by background images.
But in nearly all cases, the illuminated objects are too dakr.
So I increase power. The objects get brighter, but the background get brighter too, ut to white
Is there a way to keep the brightnes of the the background abut to power up the illumination?

Thanks in advance,
Eddy

[PhilW]

Using just the background image illumination, the answer I think is "not really, no". As Octane is a physically based renderer, the light that comes from the background and enters the camera is the same light that comes in and illuminates your objects, so changing one also affects the other. I think the best way around this is to add one or more mesh lights to assist with the lighting, or maybe even a white plane as a reflector. If you have ever seen film makers filming outdoors, you will probably have seen something similar, to enhance the natural light. And most images, even HDRIs, can fail to capture the full intensity of bright sunlight and so an additional light source in your scene will help provide the illumination you need.

[EddyMI3D]

Hallo Phil,
thank you for your explanation. I always try to make my renders such like I myself look into the world.
But I think the human eye is more versatile, nut the best in nature, but somehow better than a usual camera.
HDR abilities and the selective view of the brain. To make a comparison, the eye is the camera and the rain the post processing.

I will try try the hints you gave me. Maybe a more 'legal' way than post processing, because its part of the render.

Eddy

[PhilW]

When you are viewing a scene directly, the human eye (and brain) is capable of adjusting between very bright and very dark and making the appropriate adjustments. A render is more like a camera in that it is easier to under or over expose areas of an image, and the range of intensities recorded is narrower. I think supplementing an HDRI with extra direct lights is not really cheating, as HDRIs often do not capture the full intensity of the actual lighting, especially for direct sunlight. You can in Octane combine a background HDRI with the sun/sky model, and this too can be a useful approach.

[EddyMI3D]

Hello Phil,

I followed your suggestions and included a sphere as a fake sun into the scene.
Ok, could have used the Carrara Sun as well.
This is the result. Background is from Dartanbeck's Yosemite Bundle

[PhilW]

Definitely on the right tracks here! You mentioned Dartanbeck's Yosemite Bundle - I am not aware of that??

[EddyMI3D]

Oh, I mixed it up. It is by Dimension Theory:

http://www.daz3d.com/hdr-prosets-yosemite-pack-one
http://www.daz3d.com/hdr-prosets-yosemite-pack-two

Very high resolution JPGs and HDRs

[PhilW]

Ah yes, of course!