A challenge that arises when attempting to rotate a normal map in Photoshop is that the software does not consider the direction of the map’s vectors from the RGB channels. As a result, rotating a normal map by 180 degrees in any image processing program will result in an inversion of the normal strength – elements that should protrude will appear recessed and vice versa.
After exploring various options, I developed a tool of my own. By utilizing three.js, I am able to apply the original normal map to a plane, rotate the plane, render the plane using a Normal material texture, and the final output takes into account the rotation of the normal map.
Try it for yourselfOpen Normal Map Rotation Tool
- Flip Horizontal and Vertical
- Normal Map Strength
- …let me know!