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The sIBL background packages come with a 3k HDR file and an 8K JPG. If I use the hdr for texture in the texture enviroment instead of the RGB color, I get usually way too much light and blurry whatever. If I use the JPG I get a nice background, crips and clean, but no light nearly.

How do I properly combine a nice JPG background HDRI with the 3K HDR file, that seems to contain the light information?

Bro, apparently you have not boned up on HDRIs, as I suggested on that other thread. Until you understand how/why HDRIs work, you are going to still be figuratively and literally in the dark.. and trying to light shit with JPGs and whatnot... Go spend a half hour reading. You can do it bro! We believe in you! voo-oon.. voo-oon.. voo-oon.. VOO-OON!

Here's a quick recipe I whipped up:

1) Remove JPEG.
2) Add HDR.
3) Turn down power to taste.

That didn't answer the question. He's not trying to light the scene with the jpg. He wants to light the scene with the HDR but use a different background. You can easily do that in Cinema 4D with tags but is there a proper way to do it in Octane?

There isn't a way to do this in Octane, at least I can't think of a way to do it, YMMV. The easiest way to get the images to work might be to bring the JPG into a paint package that supports deep bit depth, at least 32 bit per color band/layer. Then paint white/grey on the sun and any other bright areas and save it as a HDR or EXR file. Or you might be able to merge the HDR file into the JPG, or vis-versa. Either way I think you will find that the JPG will not work very well anyway, even at 8k resolution. Once it's stretched around the view area you might have all sorts of JPG artifacts, blurring, etc. You just can't get around that JPG is a lossy format and even at 100% quality it's just not as good as an HDRI file. Octane will just convert the image to a 32 bit image in VRam anyway so you might as well just start with a good HDRI to begin with.

To pick this up again: Yes, even an 8k jpg gets blurry ... but at least it shows a decent background. The .hdr of the same HDRI package seems to be reduced to the lightsource parts of the image (the rest is very dark). Using the HDR file alone would look very crappy. But using the JPG seems not top produce anough light to get a properly shaded model .. it looks dull. The plane with the matte material produces clsoe to no shadow at all, even though the background is a sunset with a bright sun. Now theres octane sun simulation which can take a texture .. but I'd ratzher have all the light sin a complex scene to act as light sources off the background image ... no idea how to make this work nicely in octane without hassle.

voon wrote:To pick this up again: Yes, even an 8k jpg gets blurry ... but at least it shows a decent background. The .hdr of the same HDRI package seems to be reduced to the lightsource parts of the image (the rest is very dark). Using the HDR file alone would look very crappy. But using the JPG seems not top produce anough light to get a properly shaded model .. it looks dull. The plane with the matte material produces clsoe to no shadow at all, even though the background is a sunset with a bright sun. Now theres octane sun simulation which can take a texture .. but I'd ratzher have all the light sin a complex scene to act as light sources off the background image ... no idea how to make this work nicely in octane without hassle.

Did you try out the Visible Environment added sometime during 3.xx?

viewtopic.php?f=33&t=51679

There have been many requests for the possibility to have an environment for lighting and an environment for the background. If you use a different environment for the background you most likely would like to see that one also in reflections.

To allow this, we added an new pin "visible environment" to the render target. The environment node that is connected to this pin will be used if an eye ray or the path leaves the scene. For the direct light calculation the environment that is connected with the "environment" pin is used.

This allows you for example to use one HDRI for controlling the lighting and another HDRI as visible background.

Wow, I completely missed that! That soundslike exactly what I needed ... going to test that, thanks a lot