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Hello to all.

Could you help me please to understand how it works.
I've very simple low poly geometry created in modo.
In base material smoothing set 100% and angle 60%. Modo display this smoothing is very good (did i understand correctly, this is normals?).

After that I exporting geometry to octane render and here I've question:
1. Did I need to uncheck option "load vertex normals"?
2. Did obj store smothing groups?
3. Which I need to use, vertext normals or smoothing group in render?

Look at the pictures this "load vertex normals" options turned on and off. Smoothing are very different and I've no idea how is better and correct.

Load vertex normals uncheked Load vertex normals checked Wireframe I personnaly like when load vertex normals turned off. Result is more accurate.

What do you think?

If you need hard edges on a smooth object a vertex map might be needed.
But I also always turn off the use of vertex maps as I use a lot of third party objects. An many have really strange vertex maps on them and I have no time to correct that. I use Octanes global smoothness and it works well 98% of the times.

Here's an example of a vertex map used on an object with split normals. Same object with vertex maps turned off.

Zay thanks for your reply.

I'm simple try to undarstand why reflection is so different on front lagre faces. And how I can control it.

>>If you need hard edges on a smooth object a vertex map might be needed.
Also edge loop can fix this problem and make beveled edge more nice and rounded.

As I understand octane material smoothness didn't working if mesh initialy have smoothing groups.

Dmi3ryd wrote:I'm simple try to undarstand why reflection is so different on front lagre faces. And how I can control it.
As I understand octane material smoothness didn't working if mesh initialy have smoothing groups.

You can control it with a vertex normal map. The strange reflection comes from strange smoothness (bulging). Hard to tell what is going on without looking at the OBJ.

Try cutting and pasting back the groups/loops you want flat and have a hard edge. This unwelds them -- smoothing will still happen across the separate groups, but not at the edges where the groups meet. Though displacement utterly ruins meshes with unwelded groups, and thus is deal-breaker when any displacement is needed.