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.