Author Topic: Strata  (Read 28380 times)

Offline efflux

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Strata
« on: August 03, 2009, 01:57:03 AM »
This is very simple as you will see.

I have several progressions into other things like distorting the strata but I'm not happy with that yet. There are ways to easily distort the strata but not the way I want to do it.

Offline efflux

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Re: Strata
« Reply #1 on: August 03, 2009, 02:59:09 AM »
By the way, many of my nodes will have abbreviated names. This is because when I have complex planets I like to keep the names short or the graphs get a mess. In the above case, I renamed the get altitude because that is the crucial technique here or if the node is a major component to edit I will name it for what it does. I might tidy this system up further in future.

Offline mogn

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Re: Strata
« Reply #2 on: August 03, 2009, 03:52:58 AM »
Yes it is a pity, that Matts reserves the joy of making functions for himself.

Offline efflux

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Re: Strata
« Reply #3 on: August 03, 2009, 04:26:28 AM »
Here is one way to distort the strata:


Offline efflux

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Re: Strata
« Reply #4 on: August 03, 2009, 05:07:21 AM »
Another method. Completely different distortion technique:

Offline efflux

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Re: Strata
« Reply #5 on: August 03, 2009, 06:55:32 AM »
Next solution (possibly final).

See Matt about the nasty shadows on distorted displacements. Also, you'll see large rendering of hidden material if you render this file. This happens to large extent on many POVs I use.

Offline Matt

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Re: Strata
« Reply #6 on: August 03, 2009, 10:01:33 AM »
Where's the nasty shadow? There is some roughness due to micropolyons not being smaller than a pixel, is that what you mean?

Matt
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Offline Henry Blewer

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Re: Strata
« Reply #7 on: August 03, 2009, 12:14:29 PM »
Matt, I think what he is calling a 'nasty shadow' is the rough look of the shadows beneath the smooth perlin curves. It is a little rough. It might be a result of too few samples of the atmosphere, or soft shadow samples.
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Offline efflux

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Re: Strata
« Reply #8 on: August 03, 2009, 09:13:34 PM »
Hi matt. I've seen this shadows thing before. It crops up in virtually every render to some extent. It's not so noticeable in these renders but if you distort the displacement around a lot then shadows get jagged effects.

Also, it would be great if the renderer was able to cut out all the excess rendering that sometimes goes on i.e. beyond horizon. I don't know what the plans are with this kind of thing but sometimes on a big render there is stuff rendering for hours that isn't in the final render. It seems to crop up on specific planets and POVs like say a planet with large flat areas and a higher POV. I'm about to post another technique in another thread. If you look at this new one, it does not have the problem. At least from where the POV is taken from.

Offline efflux

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Re: Strata
« Reply #9 on: August 03, 2009, 09:17:02 PM »
The shadows may of course not be the problem. It might be coming from the geometry. I don't know. I haven't experimented to full with it yet. I understand that stretching geometry around is maybe going to create problems. If you do this to huge extend in Mojoworld you can get jagged polygon shapes but it needs to be really huge distortions.

Offline efflux

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Re: Strata
« Reply #10 on: August 03, 2009, 09:22:09 PM »
Actually the new render I'm doing now does seem to be working on stuff not appearing. I just can't see it. It's delaying for ages with no changes meaning it's doing the same thing. I don't know what kind of optimizations are going to happen in future but there are clearly hours wasted on bigger renders.

Offline efflux

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Re: Strata
« Reply #11 on: August 03, 2009, 10:19:06 PM »
I just ran a test. You can reduce the nasty jagged shadows by switching on microvertex jittering.

Offline Matt

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Re: Strata
« Reply #12 on: August 04, 2009, 04:28:25 AM »
Also, it would be great if the renderer was able to cut out all the excess rendering that sometimes goes on i.e. beyond horizon. I don't know what the plans are with this kind of thing but sometimes on a big render there is stuff rendering for hours that isn't in the final render. It seems to crop up on specific planets and POVs like say a planet with large flat areas and a higher POV. I'm about to post another technique in another thread. If you look at this new one, it does not have the problem. At least from where the POV is taken from.

The problem is that Terragen needs to calculate displacement before it knows whether something will be hidden. If it appears behind something that's already been rendered, it won't calculate any shading, lighting or atmosphere, you can be sure of that. (The only time that fails is when the approximate sorting is inaccurate from certain views.) But it still needs to calculate distant displacement in case it causes the terrain to rise into view, and when it does you need to have high detail.

It is possible to take shortcuts and guess the likelihood of the terrain being visible without fully subdividing, but those optimisations are not 100% robust (although it is possible if I can efficiently scan the depth map over large regions... something for the future perhaps). If you could tell Terragen not to render beyond a certain distance, that would help. Maybe an option I can add to the planet in future.

Matt
« Last Edit: August 04, 2009, 04:31:31 AM by Matt »
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Offline Matt

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Re: Strata
« Reply #13 on: August 04, 2009, 04:33:38 AM »
I just ran a test. You can reduce the nasty jagged shadows by switching on microvertex jittering.

I'd be interested in seeing those renders.

Matt
Just because milk is white doesn't mean that clouds are made of milk.

Offline efflux

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Re: Strata
« Reply #14 on: August 04, 2009, 05:02:48 AM »
OK Thanks. I can see the problem with the displacements. However sometimes this is very extreme - rendering stuff that is well under the distant horizon line so maybe some kind of distance control would be beneficial.

There are probably compromise methods I suppose but it would be bad if any displacements were not rendered. This is an issue with Mojoworld (except with volumetrics). Surface displacements after initial terrain layer all disappear in the distance unless you increase rendering detail to very high. It makes Mojo fast but large displacements are not seen in the distance. It also effects the general surface quality - a rough surface in foreground looks shiny in distance.

I will have to render something again to compare a bad shadow area with one improved when I enabled microvertex jittering because I binned the bad one. TG2 is rendering at the moment. I'll post back here about that.
« Last Edit: August 04, 2009, 05:06:35 AM by efflux »