Multiple Cloud layers - Lighting

Started by nreid, September 06, 2019, 02:41:34 pm

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nreid

Hello, I've recently picked up Terragen at my work and have been lurking on the forums.

I'm having a rendering issue and I hope you all can help me out.

In this test, I created two Cloud 3 layers, set them at different altitudes, and rendered.

As you can see, the lower layer is quite bright, and doesn't seem to be getting lighting information correctly.  I would expect the clouds above it to be darkening it.  I have noticed this several times.  Is there some setting I am missing?

Edit:  To clarify, I have noticed what seems to be an issue with lighting passing through from one Cloud 3 layer to another.  Is this a known problem, or is there a setting I am missing?

Matt

September 06, 2019, 11:09:35 pm #1 Last Edit: September 06, 2019, 11:14:58 pm by Matt
Welcome to the forum!

It looks like you'll need to increase the number of voxels on the lower cloud layer by a large amount. This on the Optimisation tab of the cloud layer. What is it set to now? The larger you set the localisation area (on the Main tab), the more voxels you need to maintain the same voxel size, so this might be causing problems if the localisation radius is more than 100 km or so. If you can rein in that radius, it might help. You can render very large cloud layers but usually have to pay the cost with more voxels.

I'm not sure why the upper layer isn't casting as much shadow as you'd expect. It might start to make more sense visually if you can solve the first problem. If the upper layer still isn't casting realistic shadows on the lower layer, this could also be due to voxel size on the upper layer.
Just because milk is white doesn't mean that clouds are made of milk.

nreid

Thanks! I will certainly try that out.  Both layers are set to 10 million voxels at the moment.  I expected that to be enough, but I guess I don't know.  You're right, the radius is 100-150 km I believe.  

But just so I'm understanding, you do expect light to travel properly through one Cloud 3 layer into another?  And the main culprit to check would be the voxel amount?

Matt

September 06, 2019, 11:46:53 pm #3 Last Edit: September 07, 2019, 12:18:03 am by Matt
Quote from: nreid on September 06, 2019, 11:27:59 pmThanks! I will certainly try that out.  Both layers are set to 10 million voxels at the moment.  I expected that to be enough, but I guess I don't know.  You're right, the radius is 100-150 km I believe.

For 100-150 km radius, 10 million voxels is probably on the low side.

Another reason you might need more voxels is if you increased the cloud density. It looks like you have. Putting those things together, you probably need at least 100 million for this scene. It will seem to be slower to render, but most of the slowdown happens at the beginning of the render and it might not be too bad on the overall render time.

QuoteBut just so I'm understanding, you do expect light to travel properly through one Cloud 3 layer into another?  And the main culprit to check would be the voxel amount?

It should, yes. I'm not sure the voxels are the only problem, but I think we'll have a better idea after seeing a render with more voxels.
Just because milk is white doesn't mean that clouds are made of milk.

nreid

Ok thanks!  I really appreciate the help.  I will take a look at that on Monday, if not sooner.

eapilot

I just saw this thread.  Oshyan, are you referring to the "Millions of Voxels" parameter in the optimisation setting?   Or the voxel settings in the render GI setting?

Oshyan

Quote from: eapilot on September 25, 2019, 09:23:41 pmI just saw this thread.  Oshyan, are you referring to the "Millions of Voxels" parameter in the optimisation setting?  Or the voxel settings in the render GI setting?
@eapilot I don't think I posted in this thread. Did you respond in the wrong place, or to the wrong person? :D

- Oshyan

pokoy

Quote from: eapilot on September 25, 2019, 09:23:41 pmI just saw this thread.  Oshyan, are you referring to the "Millions of Voxels" parameter in the optimisation setting?  Or the voxel settings in the render GI setting?

It's the 'Millions of Voxels' parameter in the cloud layer's optimisation tab. Keep in mind that you need to set this for each individual cloud layer if you have more than one cloud layer in the scene.

eapilot

Matt, do you have an guideline for size of v3 cloud to millions of voxel recommendations?  For example, 1000 m radius vs 100000 m radius and how many voxels would be a high quality without being overkill?

eapilot

Quote from: Oshyan on September 25, 2019, 10:23:09 pm
Quote from: eapilot on September 25, 2019, 09:23:41 pmI just saw this thread.  Oshyan, are you referring to the "Millions of Voxels" parameter in the optimisation setting?  Or the voxel settings in the render GI setting?
@eapilot I don't think I posted in this thread. Did you respond in the wrong place, or to the wrong person? :D

- Oshyan
Oops, I thought you posted but it was Matt.

pokoy

Quote from: eapilot on September 27, 2019, 05:47:43 pmMatt, do you have an guideline for size of v3 cloud to millions of voxel recommendations?  For example, 1000 m radius vs 100000 m radius and how many voxels would be a high quality without being overkill?
From my experience, you have to look at the vertical voxel count. If your cloud layer is huge (100 km and more) it will end up having less than 10 voxels in vertical axis even with higher voxel counts. My go-to number for more realistic clouds layers is somewhere around 15-20 as a minimum, 30-40 for good results (keep in mind that too high voxel counts will not gain much realism but will increase render time), as this is where clouds start to look more defined and realistic. You have to increase the voxel count quite a lot to get a number that high with huge cloud layers and chances are it will take quite some RAM that way. Hope this helps.