How can I simulate realistic fog?

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ZYX
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How can I simulate realistic fog?

Post by ZYX » Fri Jan 11, 2008 4:17 pm

Is there anyway to simulate realistic fog without setting fog on? (because fog sets all the scene, i just want an area of it with fog). Sorry if i bother any of you with all my requests for help, but please help me...

SimonLarsen
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Re: How can I simulate realistic fog?

Post by SimonLarsen » Fri Jan 11, 2008 10:16 pm

ZYX wrote:Is there anyway to simulate realistic fog without setting fog on? (because fog sets all the scene, i just want an area of it with fog). Sorry if i bother any of you with all my requests for help, but please help me...
Well, I'm no Sketchup user, but an atmospheric medium doesn't have to be one big box surrrounding you scene.
You can shape it however you want including some foggyish shapes. (:P)
I'm not sure it will look very good, but it's worth giving it a try.

Vanessa07
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Post by Vanessa07 » Fri Jan 11, 2008 10:17 pm

You must create a cube with sss material, put your scene inside, try very low values for the moment, density depend of the cube size and sss intensity

:)

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Kram1032
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Post by Kram1032 » Sat Jan 12, 2008 5:41 am

A cube with SSS is, what he does NOT want. That's the usual effect....

Well, realistic fog isn't uniform... Try to make a cloudish shape and let it scatter, as Simon Larsen said :)
If you want to get extreme, you can also use multiple layers of fog with different density (=scattering) Either way, it will be pretty hard to do it, for now.
Indigo'll support particles in some time. That will be a great improvement for these effects :)

Vanessa07
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Post by Vanessa07 » Sat Jan 12, 2008 5:48 am

Kram1032

:oops: Sorry for my english :oops:

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cpfresh
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Post by cpfresh » Sat Jan 12, 2008 5:52 am

maybe multiple 'foggy' shapes inside an overall cube of fog. light sss in all and where there is overlapping in a few places it could result in the appearance of different fog densities. dunno though. post some pics after you try some different things. gl.

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Whaat
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Re: How can I simulate realistic fog?

Post by Whaat » Sat Jan 12, 2008 6:29 am

ZYX wrote:Is there anyway to simulate realistic fog without setting fog on? (because fog sets all the scene, i just want an area of it with fog). Sorry if i bother any of you with all my requests for help, but please help me...
Fog is just a Specular material (medium) with IOR=1.0 and small scattering coefficient. Set your SU opacity to 0.0 so there is no absorption (unless you want some slight absorption).

Try a scattering coefficient of 0.03 and then tweak it from there. The fog geometry can be any shape you want but it should be a closed volume with faces all pointing out.

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ZYX
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Post by ZYX » Sat Jan 12, 2008 6:42 am

Can put objects INSIDE that fog?

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Kram1032
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Post by Kram1032 » Sat Jan 12, 2008 6:43 am

sure.
That's the way, it works, anyway ;)
Just make sure, that your fog has precedence 2 and every other material with precedence has a higher value :)

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ZYX
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Post by ZYX » Sat Jan 12, 2008 6:56 am

Got it, thanks for the help. :)

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xrok1
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Post by xrok1 » Sat Jan 12, 2008 10:50 am

what about the fog checkbox in SK. it does render fog in Indigo, how about attaching some settings to it in Skindigo Whaat?

pxl666
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Post by pxl666 » Sat Jan 12, 2008 11:27 am

u may post effect rendered - i would like to see how it turned up

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xrok1
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Post by xrok1 » Sat Jan 12, 2008 12:55 pm

here's SK fog. sorry Whaat i found the settings.
Attachments
1hr.with-SK-fog.jpg
With fog 1 hr. render MLT
1hr.with-SK-fog.jpg (44.01 KiB) Viewed 16427 times
1hr.without-SK-fog.jpg
Without fog 1 hr. render MLT
1hr.without-SK-fog.jpg (38.95 KiB) Viewed 16426 times

pxl666
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Post by pxl666 » Sat Jan 12, 2008 8:22 pm

but is this a scene put into a "box of fog" or is it a scene rendered with fog switch ON? im a blendigo user and i didnt find any fog switch - is there any way to turn it ON in blendigo?

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Kram1032
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Post by Kram1032 » Sun Jan 13, 2008 2:21 am

@pxl666
That switch simply auto-generates a huge fog box ;)
So, you can do it yourself :P

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