[Solution] How To config CrazyBump Normals Maps for Unity?

Unity Engine
1

What do I need to do to correctly convert the CrazyBump Normals before importing them into Unity?

Solution by bgolus:

in CrazyBump go to preferences by clicking this icon:


and put,

  • Normal map y-axis: Up
  • Normal map x-axis: Right

When you are ready for export,
before saving the Normal map,
set the Normal map: intensity value to half the final value you choose.
As for example, If you choose a normal map intensity of 50, then put 25 and save.

___________________________ Old question _____________________________

Dear CrazyBump fanatics,
Looking at the manual tells me that the X,Y & Z values of a normal texture direction vector are different from Unity Y up. In particular, the manual talks about Z is up. But doesn’t explain what are the other two X and Y channels.

If I export CrazyBump Normals Y up and X Right looks bad. I think I need to move the texture Y channel to the Z. I can do this in Photoshop. But also Unity talks about half of the x Y values:

“Understanding… …for using normal maps! … : The RGB colour values are used to store the X,Y,Z direction of the vector, with Z being “up” (contrary to Unity’s usual convention of using Y as “up”). In addition, the values in the texture are treated as having been halved, with 0.5 added. This allows vectors of all directions to be stored. Therefore to convert an RGB colour to a vector direction, you must multiply by two, then subtract 1. For example, an RGB value of (0.5, 0.5, 1) or #8080FF in hex results in a vector of (0,0,1) which is “up” for the purposes of normal-mapping - and represents no change to the surface of the model. This is the colour you see in the flat areas of the “example” normal map earlier on this page.”

from: Unity - Manual: Normal map (Bump mapping)

2

World space “up” in Unity is +Y, yes. But that has nothing to do with tangent space normal maps which are in tangent space.

In tangent space x and y are aligned to the texture’s UV, and z is away from the surface. That’s true for Unity, that’s true for Unreal, that’s true for every tangent space normal map.

The difference is Unity uses OpenGL style +Y normal maps and CrazyBump & UDK uses -Y normal maps. In short, the green channel is inverted between the two. This is also called Y up and Y down, because when you look at the texture itself it looks like the green channel is going “up” (or lit from above) or “down” (lit from below).

https://medium.com/@bgolus/normal-mapping-for-a-triplanar-shader-10bf39dca05a#0576

Open the texture in Photoshop / Gimp, select the green channel, invert the color.

3 Likes
3

Thanks @bgolus ! So in CrazyBump preferences by clicking this icon:

3344733--261317--upload_2018-1-7_0-49-55.png

  • Normal map y-axis: Up
  • Normal map x-axis: Right

Then you can import the normal texture directly to Unity.

  • In the texture inspector, change the Texture Type to Normal map
  • Drag&Drop the texture to the material
  • and set the Normal Map value to 0.5 (since look working perfect for me)
4

Sounds like you should be reducing the intensity in CrazyBump itself.

5

Saving Normal Map half the value inside CrazyBump is time-consuming but also a good idea.
If I put Normal Map value to 0.5 in the material inspector, is less performer than 1?

6

No, but scaling the normal also isn’t available for all shaders and gets disabled for some platforms even when it is an option (like mobile).

7

Thanks a lot! You save me a lot of time. I will export by saving Normal Map half the value in CrazyBump.