Miss-match between "merge shader" output and render

[cyphyr]

Hi there

Me again with another question that probably I should know the answer to already.  

I'm merging two terrains together, (simple dunes) a small scale, small displacement, sheared perlin PF, MERGED (Highest raise) with (Simple Mountains) a  large scale, stratified, higher displacement Perlin Mix .

The screen capture shows the dunes in green and the mountains in a sandy colour.

In the Merge shader is there a nice delineation between the green colour and the sand colour, however when this is applied to a surface layer the green starts creeping up the sides of the mountain. How can I maintain the distinction between terrain types and terrain type colour?

Oddly if I disable the compute terrain it works as expected but I have a feeling this will prove problematic later in development.

Cheers

Richard

[Tangled-Universe]

Do you use any special kind of displacement, other than "along normal"?

[cyphyr]

Nope
Attached the tgd for reference, I've altered the colours slightly since the screen cap above. Try disabling the compute terrain, changes the colour distribution but makes not a jot of difference to the terrain.
This is probably a simple NEC* error 
Cheers
Richard
* Not Enough Coffee

[Dune]

Is it perhaps because of the patch size in compute terrain? What if you feed compute terrain into the color input?

---Dune