I was working on some of the rings for my mod Evolution and, to ensure I had everything named right, looked up the RingLoder in Kopernicus' source code. After that I, out of curiosity, looked up the code of the ring shader, and came across the notes regarding up-close noise.
I wonder if that fade would be possible through some of the layer sorting modes used in programs such as Photoshop. Out of curiosity I decided to load up a ring texture of mine in GIMP, rendering a procedural noise, then using different layer sorting modes to see which ones yielded the best results without destroying the quality of the ring texture.
I would present screenshots here were it not for the fact that Imgur is giving me an 'SSL_ERROR_BAD_CERT_ALERT' error at the moment, so that's bloody brilliant.
Anyhow, back to my point. I have found that the best-looking results were the layer sorting modes 'Dodge', 'Soft Light' and 'Overlay'.
For these, the maths are as follows:
Dodge: E = (256*I) / ((255-M) + 1)
In which E is the resulting pixel color, I is the pixel color of the original image, and M is the pixel color of the noise we are applying on top.
Soft Light: E = (((255-I) * M + Rs)/255) * I
In which E is the resulting pixel color, I is the pixel color of the original image, and M is the pixel color of the noise we are applying on top. Note the Rs factor, which is computed through:
Rs = 255 - (((255-M)*(255-I))/255)
And lastly Overlay: E = (I/255) * (I+(2M/255)*(255-I))
In which E is the resulting pixel color, I is the pixel color of the original image, and M is the pixel color of the noise we are applying on top.
(Note: these are the equations GIMP uses for layer sorting. Therefore, because image editors use a 0-255 color range and Unity uses a 0-1 color range, adjustments to the equations will be necessary for them to work correctly in Unity.)
I will be testing these sorting modes further and, should they work, will try adding the best one to the ring shader (after thorough testing for glitches and memory problems before submitting a pull request of course). Here's hoping we will soon have the best ring detail, even from up-close.
Don't expect this to be possible though: