OTOY Forums

I'm trying to match some reference images and the sun is really important, coming through some glass and making nice patterns on the floor. However when I setup a daylight environment texture in octane the floor reflects a lot of the sky which is very blue, but it's supposed to be a more flat grey. If I switch to a flat color texture environment and use a medium grey color, the floor looks perfect color balance wise but of course, it has no sun pattern. While this is normal and physically accurate, I can't match the reference because I have no control over whitebalance... The photographer must have done so to compensate for the super bluish sky reflections.

I know we can't use sun + HDRI, but can we use sun for light without it's sky texture? Or change the color of the sky texture artificially?



I have tried color balancing in post and the results aren't great because it throws off all the other textures as well, which look normal under both conditions ( daylight and texture lighting ). I have tried all the camera response curves available but none get the look I'm trying to match...

Ideas? Can I make a GIANT light to emulate the sun? Will that just create massive amounts of fireflys?

You can render an alpha image and use this as mask in your compositing.

face

What do you mean? I see how I can use the alpha for changing background image, but I mean the light that is cast on the floor itself which has sunlight coming through the window and making the pattern of the window on the floor itself. I can't use alpha for that because I need the floor texture to be rendered. Unless you mean some way of doing a lighting pass and compositing that on top of the render? I don't think thats possible though?

Try to bake your environment as an HDRI and re-use it to illuminate your scene

Two things. Wouldn't baking the texture just keep the massively blue over-saturation that's already there? How does that help unless you mean manually edit the resulting baked hdri to be less saturated?

And two, octane can't bake it's daylight system...



I found a solution, but it's not pretty. I'm disabling daylight and rendering with the correct colors, then I am turning it back on to render out a direct lighting pass set to "none (0)" under GI_Mode using clay render on. That way I can get just the white sun pattern information and most of the rest of the scene is pure black.

Then in AE I am composting it on top in screen blending mode. And there it is, correct colors with correct sun shadow patterns. But twice the rendering...

Would be really nice to have a white balance setting like a real camera...

tehfailsafe wrote:Two things. Wouldn't baking the texture just keep the massively blue over-saturation that's already there? How does that help unless you mean manually edit the resulting baked hdri to be less saturated?

And two, octane can't bake it's daylight system...



I found a solution, but it's not pretty. I'm disabling daylight and rendering with the correct colors, then I am turning it back on to render out a direct lighting pass set to "none (0)" under GI_Mode using clay render on. That way I can get just the white sun pattern information and most of the rest of the scene is pure black.

Then in AE I am composting it on top in screen blending mode. And there it is, correct colors with correct sun shadow patterns. But twice the rendering...

Would be really nice to have a white balance setting like a real camera...

And two, octane can't bake it's daylight system... :
Do it with octane forMax

I don't think that works either? What steps would I take to render out an hdri with octane plugin? As far as I know it doesn't have the ability to render out a 360 like that, and using other renderer with octane sky/sun won't work, will it?

Try this:
1) in octane stand alone render out the sun sky with a temp object in the scene set to 0 opacity ( IE render out the sun sky only at high resolution. save the image in untonemapped openexr format.
2) open max and switch to the metal ray renderer
3) load in the rendered openexr file as the environment map
4) render out with the mental ray lens set to wrap around saving it as a high res HDR image.

Then you can use the 360deg rendered Hdr image how you want.

See Screen grab

it's possible to take a 360 picture from octane but needs a bit of work. in my opinion is more easy if you could render in dl, do a second pas with the new channel kernel in id-material mode and pick up the selection of the floor only for colour correction
ciao beppe

Or you can simply render a mental Ray sky and sun with 360° camera lens (just match your sun position), it's relatively similar to Octane sun&sky.