Normal Map with circle shape UE4

PSok

Hello.
I got strange artifacts in UE4 when I import my simply model and normal map.
In low poly model I've got smoothing groups.
I have baked map with SP, SD, Xnormal and I got same results. I have no clue how resolve this with bake.

low:


high:

Artifacts:

Scruples

chances are it's banding, hard to say from 1 picture as I can't tell if that's a specular highlight or reflection. http://polycount.com/discussion/148303/of-bit-depths-banding-and-normal-maps

Obscura

Use "UserInterface2D" compression. This will result the normal map being uncompressed, and also to be in 0-1 range, instead of 1,-1. So put the uncompressed normal map in the material in a texture sampler. Then take the rgb or that, multiply by 2, and then subtract 1 from it. Now its back to 1,-1 range. Then this can go into the normal input.

You can also try dithering but with such a clean roughness, it will be only worse. You also have some shading problems, dont you?

PSok

Obscura said:

Use "UserInterface2D" compression. This will result the normal map being uncompressed, and also to be in 0-1 range, instead of 1,-1. So put the uncompressed normal map in the material in a texture sampler. Then take the rgb or that, multiply by 2, and then subtract 1 from it. Now its back to 1,-1 range. Then this can go into the normal input.

You can also try dithering but with such a clean roughness, it will be only worse. You also have some shading problems, dont you?

I've change to UserInterface2D like you said, also i do multiply by 2 and subtract by -1 but I got error with normal map, I do something wrong?.
It's not my main scene I only checked asset with UE4.

Obscura

Now on the detail panel on the left, set the texture sampler to use linear color sampler type. Also make sure sRGB is disabled on the texture.

It need to be noted that this will give you much larger texture size/memory usage, because you use an uncompressed texture.

PSok

Super! It's worked
Also when I saved Normal Map in .exr it's gave me same result. 
Thanks for helping guys!

PSok

Ok, I try something else. From SP i have saved file to .tif 16 bits next in PS I have converted it to 8 bits targa (dither) and problems gone.