Full breakdown of Merge Shader usage..

[yesmine]

I've been testing several clip files I've located in the Forum to try to understand exactly how fake stone shaders for varying sizes of rock are merged together to create the rocky field effect. I've been playing around with several of them, and I want to I think I have some understanding of how a set of fake stone shaders are linked together through a Merge Shader to combine them before they output to the Surface Shader node. But for some reason, when I start trying to set the sizes to be what I want, everything that is plugged into the "Shader A" node of the Merge Shader seems to almost shrink into the ground and the colors wash out and become much less prominent. Whatever is plugged into the Input node seems to come through fine. If I test an individual fake stone shader by by-passing the merge nodes and linking directly to the Surface Shader "Input", they all display just fine. So I'm pretty convinced it's happening because of the Merge Shader, but so far I'm very confused because I can't seem to merge them correctly.

Does anyone know of a full explanation of how to use the merge shader, and what the right settings would be so that each fake rock is passed through perfectly and displays as intend?
Thanks..

[Dune]

Did you try the 'choose by altitude (highest raise)' method, and smoothing the surface layer with the stones?

[yesmine]

Hallelujah! Thanks Dune...
   I've been experimenting with a fake stones clip called 'Fake Stones 0.01m-1m', which has four groups of stone sizes split into two sets, each with a Merge shader combing them. Then, those two merge shaders are combined using a third "Final Merge shader". Somewhere in my hours and hours of infinite tweaks, I'd left the merge shader on the larger stones set to "Choose by altitude: ALL"...("choose by altitude: Highest (raise)" made me think that might display only the highest stones; I thought 'ALL' sounded like I'd get it all.) Obviously that wasn't right. 

Still, I had colored the stones bright solid colors so they would be very distinct and I could see the complete effect. But when 'choose by altitude' is set to "ALL", each stone color fades by about 50% and the stones themselves seem to sink half way into the ground. I definitely like having that kind of control, but "ALL" doesn't seem to accurately convey that kind of result (though I'm pretty sure it's me who doesn't yet understand what 'choose by altitude' means in this context.)

Fwiw, the '?' icon in the shader window, which takes you the online Wiki, only shows a picture of the shader window and describes it's for merging shaders. Just my opinion , but it might help new users if the Wiki included a clear explanation of what all those options actually do and what the labels are meant to convey, perhaps with images to show the result (an idea that perhaps all us users could contribute to piece by piece.)

But I'm making progress..so thanks for the help (again)..

[Dune]

You're welcome. A little (a lot of) experimentation in simple setups, varying parameters gives you enormous insight (and surprises).

[yesmine]

I've added an image to show what I'm talking about now, and basically this is same set of fake rocks as before and I thought everything was under control. However..

I'm checking two fake rocks with essentially  the same settings except for sizes and colors. They connect via a Merge shader to Planet 01. The issue is that when either one is plugged in alone, it's fine...they sit on the surface and the color is clear--but when I combine them through the Merge node, the one plugged into the Input shows as expected, but the one on the Shader A connection seems to loose 95% of it's color and everything else.

As Dune corrected for me earlier, the Merge mode is set to 'Choose by altitude: Highest (raise)', and Mix is at the default .5 with the merge for Colour and Displacement both set to Mix (normal). I think that's basically the defaults. But I need to get both of them to display fully, as they do individually? (Is there a way to get them both plugged in without merging them?)
Thanks..

[Dune]

You're doing something 'wrong' here. Nothing is really wrong, but this wouldn't work as you wish, obviously. Best is to have the 2 stones merged and added as input in a (no color) surface shader, which gets its input from the planetary grass.
And if you merge highest raise, you're bound to loose some of the individual stones, as the other set might prevail, so to speak.

[yesmine]

Thanks Dune, I'll check on the Surface Layer shader and see how it goes. To clarify this for myself though, is there no way to simply have 2 fake stone shaders and have each of them show up completely, with all the colors and no matter which is 'highest'? I suppose what I'm hoping for is, since I've made fake stones in different sizes, densities, and colorations,  to have them all show up as-is. If merging them with highest raise will necessarily loose some of them, or merging causes all the colors to fade out of some stones, there must be some other way to get them in.
Thanks..

[Dune]

You can stack them, but some stones will appear on top of others, and you get totally different stones. But it's good to experiment with that as well. Or (inversely) mask the different stones by fractals, so 2 stones' types don't come near eachother.