Lines

Started by rcallicotte, February 11, 2008, 11:40:39 AM

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rcallicotte

From time to time, I have run into these lines in the terrain.  What is this?  I have checked all of my fractal breakups and I'm well within range, as far as I understand it.  This is not part of a loaded terrain.
So this is Disney World.  Can we live here?

Tangled-Universe

Well I think this is just the fractal pattern, nothing really strange.
I don't know which ranges you consider to be good or not but I think you'd check them again.
As far as I know this is the result of high contrast (>1) settings in your fractal settings.

Martin

monks

You might want to alter the fractal noise you are using- the worst offender for those lines is the 'fractal ridges' setting- not sure whether TG uses this nomenclature. You could always blend them out with another noise type.

monks

Virex

I've had those lines a few times myself, but only when looking at a terain from a minute distance compared to the detail size.

rcallicotte

Thanks for the suggestions.  I've looked through all of these things without success.  I'll keep hunting.  I did find some places on the terrain that did not have this problem.  The terrain file is loaded nearby to this spot, so I'm not sure if that would do it or not.

@TU - fractal noise is set really low on the low side - .01  and it's good to know about the > 1 for contrast.  In this case, I don't have any fractals colors >1.

@monks - the fractal range is all good - .01 is the highest of the low numbers and in some cases I go a lot lower.  Not using the Perlin Ridge for my Tweak Settings

@Virex - I'm at about 150M high in the preview you see here.
So this is Disney World.  Can we live here?

Tangled-Universe

Quote from: calico on February 11, 2008, 03:45:10 PM
Thanks for the suggestions.  I've looked through all of these things without success.  I'll keep hunting.  I did find some places on the terrain that did not have this problem.  The terrain file is loaded nearby to this spot, so I'm not sure if that would do it or not.

@TU - fractal noise is set really low on the low side - .01  and it's good to know about the > 1 for contrast.  In this case, I don't have any fractals colors >1.

@monks - the fractal range is all good - .01 is the highest of the low numbers and in some cases I go a lot lower.  Not using the Perlin Ridge for my Tweak Settings

@Virex - I'm at about 150M high in the preview you see here.


When reading Monks comment and also Virex's I thought one of them was right.
By the way, I'm not putting a no go on contrast levels >1. There are lots of situations where contrast levels >1 are very very useful.
So only in this particular case I thought it was the problem, but it apparently it wasn't.

rcallicotte

So this is Disney World.  Can we live here?

sjefen

I think I remember reading about this a long time ago. I think it's a fractal issue, but I'm not sure.
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Mr_Lamppost

How many octaves are there in your terrain fractal?  I often find I get these lines if the total number of octaves is low.  As previously mentioned Perlin Ridges is the worst offender but they do show up in the other fractal types.  They can be hidden by adding a second low amplitude displacement fractal with a small feature size.
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rcallicotte

Thanks, Mr. L.  I'll explore this and report back.
So this is Disney World.  Can we live here?

Oshyan

Very low noise/roughness settings will cause this kind of thing, as well a small number of noise octaves (small range between Lead-in and smallest feature scale).

- Oshyan

Tangled-Universe

Thanks Oshyan, this is very useful to know.

dandelO

What is considered a small No. of octaves? When I'm creating terrain in T2 I try to keep the noise octaves to between 10-25, I still occaisionaly suffer with this fractal lines 'problem'.

I've read here before to try and break them up with a smaller displaced fractal shader but the trouble I have there is getting the breakup evenly over the fractal lines without losing too much of the original terrain shape I started with. Should I be using the 'breakup' or just applying the smaller fractal on top of the first terrain?

This is one of the little annoyances I've had with TG2 that I've not been able to fully work around yet.

rcallicotte

@dandelO - Can't answer your question, but I remember the max octaves allowed is around 40...maybe exactly 40.  Hope someone like Oshyan has something for you.  This is interesting and helpful.
So this is Disney World.  Can we live here?

Mr_Lamppost

I consider 7 or less to be a low number of octaves.

Here is a quick example of adding a second layer of fractal displacement to mask the lines.

The tgd is there as well just enable the second fractal terrain to see the effect.

Smoke me a kipper I'll be back for breakfast.