### Author Topic: Intersect Underlying - combining several layers problem  (Read 377 times)

#### Roberts

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##### Intersect Underlying - combining several layers problem
« on: November 21, 2018, 02:07:47 PM »
Hi everyone!

Iīm having a hard time struggling with the intersect underlying (IU) effect. However, I have managed to find settings that gives me satisfying results. One of the keys seem to be the patch size coming from the compute terrain node. Larger patch size fed into the layer with the IU effect gives a "wider" pattern, following larger depressions in my underlying terrain. I understand this (I think:-)) and it makes sense to me.

What doesnīt make as much sense to me is the following problem in the images below.

The first (green) one shows larger depressions. They are in a layer fed with a larger patch size (2000)

The second (pink) image shows smaller scale depression. They are in a layer fed with a smaller patch size (20)

What I want is for the smaller depressions AND the larger depressions to render. As you can see in the second image, the pink layer completely covers the underlying green layer in a way I dont understand. I want the pink to be ON TOP of the green layer, but still showing the green layer. This should be possible, as they are not really covering the same areas of the terrain. But, none of the green layer is visible anymore. Why is that?

I know that several layers using the IU effect can indeed lay on top of each other and NOT completely cover each other, if they are stacked like in the last image below. But the problem then is that both layers are fed with thw same patch size, which in my case, doesnīt give me the look Iīm after.

Does anyone have any suggestion on how I can solve this?

Regards

Roberts

#### Dune

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##### Re: Intersect Underlying - combining several layers problem
« Reply #1 on: November 21, 2018, 02:46:15 PM »
Would something like this give you what you need?

#### Roberts

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##### Re: Intersect Underlying - combining several layers problem
« Reply #2 on: November 21, 2018, 04:55:20 PM »
Dune, thank you so much for your reply and suggestion. But no, I donīt think itīs really the effect Iīm after.

I would like to add finer detail (smaller scale depressions) on top of a layer with large scale depression. To be clear, I donīt actually want FURTHER depressions than in the underlying terrain. That is, no displacement intersection, I just want both layers to find and colour different scale depressions in a terrain, so to speak. Hope that makes sense.

What I want to achive is this:

First a layer that has large snowfields, in valleys and other larger depressions. That is the green layer in the first image below.

Second, a layer with finer depressions, simulating snow that fills crevasses and smaller depressions. That is the pink in the second image below.

As you can see in the third image, when both layers are enabled, they interact in a way that completely spoils the look. The green is no longer constricted to large patches, instead it nearly covers the whole terrain. It seems the last pink layer somehow destroys or overrides the previous layer. ( But atleast now I can see both colors at the same time, which I didnīt before. Not sure why, but anyway..)

Attached is also a tgd to illustrate the problem. The actual terrain I want to use is a digital surface model from the Japanese Space Agency, but I`ve replaced it with a fractal terrain instead. The idea is the same anyway.

Roberts

#### Hetzen

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##### Re: Intersect Underlying - combining several layers problem
« Reply #3 on: November 21, 2018, 05:23:32 PM »
What version of TG are you running, because this is what I get from your TGD file. The green and pink stays the same when I switch off SLs and the green is the same as your image when both SLs are on. The pink seems thinner than yours.

Might I suggest instead of plugging into child layers, you output white and use that as a mask input to drive the green and pink.

Also another consideration is that your DEM doesn't have a lot of lower scale detail ?

#### WASasquatch

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• The Homeless Landscape Artist
##### Re: Intersect Underlying - combining several layers problem
« Reply #4 on: November 21, 2018, 06:51:21 PM »
This is simply what I did, using the logic we often find ourselves doing I converted your intersection surfaces to output white, and used them to mask the primary surface layers, which are currently outputting the test colours.
« Last Edit: November 21, 2018, 06:54:59 PM by WASasquatch »
Art can be a window into the soul

#### Roberts

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##### Re: Intersect Underlying - combining several layers problem
« Reply #5 on: November 21, 2018, 08:01:19 PM »

Also another consideration is that your DEM doesn't have a lot of lower scale detail ?

No it doesnīt (itīs approximately 30m in resolution). But thatīs fine enough. The problem Iīm having is that I DO get the detail I want in each separate layer, but when several layers are enabled and interact they mess things up.

Since Hetzen asked what version Iīm running (itīs 4.1.25) and WASasquatch managed to render it properly, I guess itīs the older version Iīm using that is the culprit (?). When I render your scene WASasquatch, the whole terrain is green... So basically, in version 4.1.25 it doesnīt work to use the IU layer as a mask?

Using the IU layer as a mask was actually what I tried first, days ago, but since it didnīt work I plugged them in as child layers instead which seemed to work better, but not really all the way then.

So I guess I have to get a new maintenance, if there is no other workaround. Thatīs a bit saddening, Iīll have to think a bit more untilI decide If Iīll do that. But Iīm glad for all your help!

Thank you all.

Regards

Roberts

#### Dune

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##### Re: Intersect Underlying - combining several layers problem
« Reply #6 on: November 22, 2018, 06:10:35 AM »
Your file works alright, Roberts, but you have to reverse the masking. Check this out. Is this your solution? And this is in a very old version (3.7).

#### Roberts

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##### Re: Intersect Underlying - combining several layers problem
« Reply #7 on: November 29, 2018, 03:53:41 PM »