Author Topic: Isolate clouds and haze  (Read 2285 times)

Offline Eneen

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Isolate clouds and haze
« on: February 24, 2012, 07:49:28 PM »
Hi,

Is there any way to render only clouds and haze (keeping illumination and shadows), eg.by making density or opacity map?

Best regs.

Offline Matt

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Re: Isolate clouds and haze
« Reply #1 on: February 24, 2012, 11:07:52 PM »
You can render a cloud-and-atmosphere pass by going to the render node and turning visible surfaces OFF and visible atmosphere ON. The lighting of the clouds and atmosphere will be the same as if you rendered everything together. I hope that's what you mean.

Matt
« Last Edit: February 24, 2012, 11:10:26 PM by Matt »
Just because milk is white doesn't mean that clouds are made of milk.

Offline Eneen

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Re: Isolate clouds and haze
« Reply #2 on: February 25, 2012, 05:51:20 PM »
Matt,

Not exactly.
Problem 1: attach clouds to sky in any 3d rendering software sun and sky system.
Problem 2: lighting with hdr with sun as few pixels is a lot slower then sun&sky with sun as infinite light
Possible solution 1: light with hdr mapped on sphere with "hole for infinite light sun" (made as transparency or with geometry, for materials and camera to see sun disk and hdr) - easier to do but still slower then solution 2
Possible solution 2: make additional clouds and haze and map it with transparency map on sphere.
Question: is it possile to make such transparency map isolating clouds and haze from background sky in Terragen?

Best regs.
Alex.

Offline Matt

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Re: Isolate clouds and haze
« Reply #3 on: February 25, 2012, 10:09:26 PM »
Rendering only clouds: You can turn off enable primary on the atmosphere and any other cloud/haze layers that you don't want to be visible to the camera. They can still affect lighting of everything else if enable secondary is on. On your Sunlight node, turn off visible disc.

Saving alpha channel: You can view the alpha of any render by pressing 'A' in the Render View. You can save the alpha image with the 'Save' button while the alpha is being displayed. Note that the alpha image will contain three channels because some atmospheric components have spectral opacities (Rayleigh scattering), but you can convert to greyscale if you want a simple alpha map.

If you're rendering a sequence, make sure you output "extra output images" - these will be your alpha images.

Matt
« Last Edit: February 25, 2012, 10:12:15 PM by Matt »
Just because milk is white doesn't mean that clouds are made of milk.

Offline Eneen

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Re: Isolate clouds and haze
« Reply #4 on: August 16, 2012, 10:29:18 AM »
Thanx alot Matt, I'll try that.
Sorry for late reply, there was no time to dig into TG.

 

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