There a few factors that can result in weird shading errors.
1. Base poly flow (both on the low poly model + highpoly model). If the polyflow is odd it will provide weird results all around. A clean and flowing mesh will provide good bakes and unwrapping, so if its off it can cause a huge headache.
2. When you bake to a low poly model, you want to ensure the low poly is already triangulated. Sometimes if you bake it to a quadrified mesh, and you import it into a game engine, the game will auto triangulate the model. Now it could retriangulate it differently then what you baked it too (although it displays a quad, 3D programs still form meshes in triangles even you can't see it). Now, normals are specific to a mesh face, so if the triangles are different it can look weird.
3. The bake cage. Not sure how blender works, but in 3DS Max you have a cage that contains your 2 meshes. (Low poly + High poly) The cage is like the "out of bounds" for the baking rays. It's tough to describe, but basically the tighter the cage is around the models the more accurate the bake. If part of the mesh passes through it, it will just not have normal information there which is no good. So you gotta find that happy medium of getting it as close as possible but not to close. In max you can manually adjust this cage.
4. So if the model is good, no probs, and the bake is setup correctly then it could be channels. Oh snd another thing, you cant not rotate a baked normal map. Thats a no no as well.
Normal maps are awesome, they can do amazing things. Take it from aguy who baked every single part on his bike, man its a headache if something is not looking right.
1. Base poly flow (both on the low poly model + highpoly model). If the polyflow is odd it will provide weird results all around. A clean and flowing mesh will provide good bakes and unwrapping, so if its off it can cause a huge headache.
2. When you bake to a low poly model, you want to ensure the low poly is already triangulated. Sometimes if you bake it to a quadrified mesh, and you import it into a game engine, the game will auto triangulate the model. Now it could retriangulate it differently then what you baked it too (although it displays a quad, 3D programs still form meshes in triangles even you can't see it). Now, normals are specific to a mesh face, so if the triangles are different it can look weird.
3. The bake cage. Not sure how blender works, but in 3DS Max you have a cage that contains your 2 meshes. (Low poly + High poly) The cage is like the "out of bounds" for the baking rays. It's tough to describe, but basically the tighter the cage is around the models the more accurate the bake. If part of the mesh passes through it, it will just not have normal information there which is no good. So you gotta find that happy medium of getting it as close as possible but not to close. In max you can manually adjust this cage.
4. So if the model is good, no probs, and the bake is setup correctly then it could be channels. Oh snd another thing, you cant not rotate a baked normal map. Thats a no no as well.
Normal maps are awesome, they can do amazing things. Take it from aguy who baked every single part on his bike, man its a headache if something is not looking right.