Hi Azims!
You're asking the tricky questions, but they're good ones! I'll do my best to explain the process we're implementing with the plugin so that you can set it up manually for now.
1. We bake several infopasses that UE can use to correctly display the static lighting results from Octane. These are all 32-bit .exr files using linear colour space.
..1a. Go to your render target and check the "Raw", "Diffuse" and "Diffuse Filter" beauty passes. Diffuse is going to be the effect of light on your surface and Diffuse Filter will be the unshaded base texture.
..1b. Under Info Passes check "Bump and normal mapping" and "Shading Normal". You can also check "Tangent normal" if you want to work in tangent space. I find using Shading Normal fixes up a common problem UE has with importing smoothing groups from C4D.
..1c. Check "Ambient Occlusion" as well.
..1d. In your Imager node change Response to "Linear/Off".
..1e. Use the Path Tracing Kernal or PMC for best results when you bake. Direct Lighting is fast but doesn't achieve what you're trying to do.
2. Set up your meshes with good, non-overlapping UVs. If you need overlapping UVs for your bitmap materials set up a completely unwrapped and non-overlapping UV set in the second UV channel. Unfortunately you can't use .obj to do this as it only supports a single UV channel. Use Alembic in this case instead.
..2a. Bake each object's surface and save the results of those infopasses mentioned above as .exr files. The best way to do this is to set up each mesh with its own object layer map and then each mesh with a unique baking ID. If you plan to bake more than once, set up multiple render targets with multiple baking cameras, each with its own baking ID target. Then you just have to click each render target and output the results. This is the most time-intensive step.
..2b. Since you're baking lighting results, use whatever environment your in-game scene will be using.
..2c. I believe I saved the infopasses as untonemapped.
..2d. They'll be separate .exr files.
..2e. You'll want to target the highest res output you can. For UE this means 4096x4096. I would even recommend going for 8192x8192 and follow the steps here to enable 8k textures in UE:
https://docs.unrealengine.com/latest/IN ... utionlimit
3. Import your meshes and textures to Unreal Engine. Your .exr textures should import as 16-bit linear colour textures. This part is very important so verify that a couple of them worked. For this manual process I found it easier to set the origin of each mesh to 0, 0, 0 with the mesh's geometry offset from that. This means when you import to UE you just zero the position and rotation for your meshes and they're in exactly the right place.
..3a. Set up your material like this:
..3b. Also note that in the sidebar you should uncheck "Tangent space normals" if you're using the Shader Normal infopass.
I'll attach an example .ocs file so you don't have to manually go over every step. Setting up the UE material should be pretty easy. Make sure if you're doing a base material to instance off of in UE that you use your .exr textures as the preview material or the colour space will be wrong.
We're going to release a sample scene with the first alpha of the plugin that will contain examples of all of the above. It's a pretty arduous process so you can see why we're plugin-izing it. I'm a little behind my schedule but I'm hoping we'll have something to download real soon.
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One thing I'm quite excited about is accurate rendering of emissive materials, giving UE access to proper emissive surface lighting.