Jaggy edges on Displaceable Cube

[Pitmatic]

Hi

I am relatively new to Terragen and have come across something that no doubt everyone will recognise straight off and I apologise if this has been covered I might not know the right word to search for

Anyway I have a scene with displaceable cubes making a sort of fantasy stone circle what have you and the edges of the cubes have jaggy edges? I am using a power fractal to bump up the surfaces of the cubes but there is on the corners these little jagged edges appear in the render and no matter what I do they stay put unless I displace the cube so much they become boulders which is not what I want to do

Any ideas appreciated

[Dune]

Welcome to this forum, Pitmatic.
You are most likely using a negative displacement or offset, which causes corners to act weirdly. I've added an example that does works properly.
Good luck on your setup, and do show us what you make!

[Tangled-Universe]

Negative displacement also happens when you displace with a positive displacement value, as the fractal by default creates negative values, thus also negative displacement.

I think it's mostly because of (the lack of) edge smoothing in his example.

[Dune]

That's right and that could be his problem indeed. In my sample I used all defaults, so also negative displacement areas and the deafult 0.1 edge smoothing, which works well. It may work even better with a positive offset of half the displacement value.

[Pitmatic]

Thanks for that Dune   I seem to have different default values to you is that a setup thing?

my defaults for the powerfractal are below I changed to your projects example and I still had an odd edge issue though but do you mean by edge smoothing the cubes round radius setting I was using 0.01 and it seems that 0.1 makes things much better after a lot of twiddling and test rendering

And Yes I will share when my result is not too rough looking

[Dune]

Well, I didn't use defaults in the power fractal; you always have to adjust the settings to what you need. For a cube of a few meters the largest size should only be a few meters max, the feature size something like the size of the bumps you want to have. The default is meant more for (large) terrains.
In the cube I used defaults, and yes, 0.01 (1cm) is very small, especially with displacement larger than that. You always need to think in real sizes.

[KyL]

Hi there,

this is happening because of your negative displacement values making the cube "shrink" on itself. It is fine on the large faces but on the edges they are displaced so much that they go through each other (if this make sense put that way)

The easiest fix is to apply a positive offset equal to half of your displacement. For example if you have a displacement of 0.1, add an offset of 0.05.
This way the displacement will be only positive and the cube surface is only going to be displaced outward the cube.

Cheers!

Also, first post after seven years on this forum 

[Dune]

Well, welcome to the forum, KyL! Seven years, and no posts? I hope you'll be posting some stuff you made.  I mentioned the offset

It may work even better with a positive offset of half the displacement value.

, but you explained it in more detail. I tend to forget some users need more explanation than just  a few words