Baking normal map from high poly to low poly

Hi guys, thank you for coming. :smiley: I have encountered 2 problems when baking the normal map from high poly to low poly. I would be appreciated if there is any help.

I have 2 mesh, 1 is the low poly, and the other one is the clone of that mesh with a subdivide modifier up to level 3 (I call it high poly).

From P1 in the picture, there is a octagonal cylinder with a circle cylinder “shadow” baked from high poly on my octagonal cylinder. But what I want to is a circle cylinder (or near circle) without corners after the normal map has applied. I have followed Blender Guru’s Anvil tutorial but I don’t feel like I have missed something.

For P2, my normal map appears some red and green area. From what I’ve learnt from blender guru, it is not a good normal map. I tried changing the ray distance setting, but no matter how I set there are red and green.

My blender file

Thank you so much if you can shed some light for me or other new users who might face the same problems.

P1) A normal map does not modify your geometry. An 8-sided cylinder is an 8-sided cylinder. You can’t make it “without corners”, if I understand correctly what you’re asking. If you want it to look circular, use more sides.

P2) Ray distance won’t help you here. Those are areas where:

  • your high-poly and low-poly deviate from each other, substantially, and, because of that (very important):
  • the normals on your low-poly are pointing in such a way as to miss intersection with the high-poly completely:

On that particular rim of the cover, all the rays that are shot from the low-poly will always miss the high-poly, no matter how you adjust the ray distance.

You’ll either need to edit the objects so that they follow each other more closely (very important especially for these concave surfaces), use a cage for baking, or rethink your approach and make the sides and cover their own meshes, just as they are distinct objects in reality.

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