Obvious Contour line Problem

[saturnapollo]

Guys

Don't really know how best to describe this problem I've had since the first download of Terragen many years ago and it's still with me. Using the latest 2.3 version and it is still noticeable that there are often very obvious contour effects where it looks like two pieces of landscape get joined together. Noticeabe by a change in colour shade and a very straight/curved line. I've attached an image with arrows pointing to the defects. Obviously I can take them out in Photoshop, but in large renders it is very time consuming.

Would appreciate any advice please.

Many thanks.

Keith

[dandelO]

Those are a common problem when using certain flavours of fractal noise in TG. You'll see them with ridged, billows and any of the Perlin Mix noise flavours.

The best way to get around those, if you need to keep your landscape features as they are, is to add a smaller scaled fractal on top of that one, this is usually enough to break up the fractal lines with a little trial and error.

An even better way to completely avoid fractal lines is to use 'Perlin' for the noise flavour, those lines don't happen at all with Perlin but, I understand you sometimes need ridges and billows.

[saturnapollo]

Many thanks for your reply.

I'll try what you suggest, but at least it isn't something obvious that I'm doing wrong. Perhaps a future update may solve this problem?

Keith

[digitalis99]

That's not something that can be fixed by an update, because it's not broken.  That's what the noise looks like.  Try using a much smaller "Smallest scale" value in your PF, that will give much finer detail to break up some of the more obvious large scale lines.

[jo]

Hi Keith,

By their very nature the billows and ridged versions of the Perlin noise incorporate these sorts of structures. Probably the best way to deal it with is how dandelo suggests. It would be good to have additional noises which give the same sort of effect without the artefacts.

Regards,

Jo

[saturnapollo]

Many thanks both Jo and Digitalis99 for both your replies. I'll give it a go!

Keith

[elipsis1]

Those are a common problem when using certain flavours of fractal noise in TG. You'll see them with ridged, billows and any of the Perlin Mix noise flavours.

The best way to get around those, if you need to keep your landscape features as they are, is to add a smaller scaled fractal on top of that one, this is usually enough to break up the fractal lines with a little trial and error.

An even better way to completely avoid fractal lines is to use 'Perlin' for the noise flavour, those lines don't happen at all with Perlin but, I understand you sometimes need ridges and billows.

How exactly does one add a smaller fractal on top without it altering everything too much?

I know, "small" is the key, but a small step by step would help a noob like me a lot

[Hetzen]

You have several options in how you could introduce smaller noise. A successful way of breaking up ridges, is by using a redirect shader, with one or two PFs plugged into x and z. What this will do, is push/pull your landscape to the amplitude of what ever the PFs connected to the redirect are outputting. It's a good idea to keep the displacement of the PFs lower than their feature scale, as this will avoid pushing the landscape too much resulting in 'pond' like structures. But then again, that maybe an effect you're after. It's a bit of trial and error to get right.

[elipsis1]

I think I am getting the concept, just figuring out where to connect it all is my issue.

So would you use the "blend by" portion of the terrain to assign the redirect? And then the redirect, how do you connect the power fractals?

[Hetzen]

In this instance, you would plug your terrain tree, the last link of, into the first input on the redirect, then create a new PF with its displacement 'on' to plug in the second and fourth input. The displacement from the PF will push and pull what ever displacement is coming into the redirect shader. You need to set up your PF scales and displacement amplitude to get this to work to the effect you are looking for.

[elipsis1]

Thank you!