thanks for the answer. but somehow i dont get it. unreal supports candelas, lumens and "unitless" values for lights. you cant enter watts.
since i want a physically correct look in unreal i m using lumens or candelas. but which one i m supposed to use so it looks fine in octane without breaking the unreal scene?
The short awnser is that it is generally better to leave your unreal scene as is, and change the settings on the imager node to try to match exposure levels.
This problem exists because unreal uses various post processing that influence how bright a scene appears.
Additionally unreal uses a somewhat different BDRF that can result in different lighting results with the same input values.
The main unreal post process features that influence brightness are
- Tonemapper (including exposure),
- Eye adaption
The plugin converts light lumen/candelas values as the same to octane. However, octane has different post processing,
which can result in different end results as we do not directly convert tonemapping settings to the octane rendertarget.
There could be a mistake on the plugin side.
To check if there is a mistake you can do a baseline comparison of your scene as follows
- In the Unreal viewport: Select the following buffer visualisation: Lit -> Buffer Visualisation -> Post-Tonemap.
*You should now see your unreal scene as it is before any postprocessing.
- Create a new Octane rendertarget
- Go to the imager node
- In the imager node set the Response curve to "Gamma 2.2.
The octane results should now match the unreal results as close as possible.
If there are still large differences please let me know.