Okay so briefly, what I want to accomplish is a sort of ground hugging fog effect in Poser 7.

I've spent several hours playing with the atmosphere effects in the materials tab, and I can make fog be in the distance, up close, and even make it start above ground.

Is there some setting which will define the maximum height of the atmosphere effect? Or is there a better way of making low fog?

 For something like that, Nerd's Fog Tool is probably best. You can also try my free Fog plane, it's in Free Stuff.. WAYYY back. You could probably make something better with a few planes and ome procedurals nowadays. Same principle though :) - some semi-transparent planes. Much easier to control than the atmospherics in Poser. Those are cool WHEN they work, but it's too often a hit-AND-miss situation IMO L

Ah thanks Trekkie. I wondered if it would be easier using planes but hope (the bane of us all >.>) left me wondering if it might be that I was missing a simple 'make fog work' button somewhere. I'll play about with some planes now :P

Quote -  For something like that, Nerd's Fog Tool is probably best. You can also try my free Fog plane, it's in Free Stuff.. WAYYY back.

I didn't know you had a fog plane!  I'll have to look for that.

I do agree about Nerd's Fog Tool.  I have that and have used it in 3 or 4 images in my gallery and absolutely love it.  

BagginsBill made a shader for a plane in the Rdna Node Cult Forum.

Sorry, I cannot remember the title of the thread at the moment.

 I'm thinking something like a turbulence node with displacement and transparency might do a swirling effect in more than one direction. 

This is giving me ideas.. I'll have to experiment L

Something like this?

In that same node is a 5 connected to Clouds. That makes 5 inches of variation.

...damn.

Well, fog goodness sakes!

BB to da rescue ................... again.

Nice one Bill.

cheers,
dr geep
;=]

 Ooh neat!

What's the light setup in that one, BB? Lights AND atmospherics together always seem to be my biggest problem. As far as I can tell, the atmospherics are very depending on the RIGHT light..

Or am I wrong there, too?

Excellent, thanks guys. I'll mess about with this in the morning. I'm not to worried about using the atmospheric over props tho, props seem to equal faster renders while atmosphere makes more detailed fog, I guess its a toss up.

Thanks again for the help.

I wonder if it can be animated by using the variations and changing height. Would be cool to ad windforce wouldn't it.

Any idea's whats causing the massive white flare over the whole screen?

At some point the cable between density and blender came unplugged. Attached render now the fog works, thanks VERY much for the help guys. =]

Quote -  Ooh neat!

What's the light setup in that one, BB? Lights AND atmospherics together always seem to be my biggest problem. As far as I can tell, the atmospherics are very depending on the RIGHT light..

Or am I wrong there, too?

Correcto. Here is the brief answer. Poser atmosphere is invisible unless a light shines on it. It is not the same as smoke. If you shine a spotlight on the fog such that some parts are lit and some not, the unlit parts will disappear, instead of looking like darker, unlit fog.

I have not experimented to see if IBL counts as "a light shines on it". To answer that, somebody should try rendering with just a plain white IBL and see what you get.

I used my usual two-lights here. An IBL for ambience, and an infinite at somewhere between 60 and 100% - can't remember what value I used. I did not use GC.

--- long answer ---

I have not worked extensively with Poser atmosphere. I've done a few little experiments, but not sufficient to be authoritative. This is what I believe:

The effect is created by the internal assemblage of a series of parallel infinite planes.
(Could be bounded, not infinite, bounded by camera viewing frustum - not sure - would need to develop various tests involving mirrors to find out if the atmosphere extends in all directions.)

The atmosphere planes seem to be parallel to the ground plane. I.e. the normals are straight up in Y.

The atmosphere planes are spaced apart in proportion to the Volume_StepSize.
(When you use a higher Volume_StepSize, rendering is faster, and distinct planes of fog become visible.) I do not know what the units are, but it could be inches.

These planes are not shaded as a normal surface would be like the ground plane or a one-sided square. They are always 100% transparent, meaning that whatever is behind them is always rendered at 100% brightness. In addition, they generate some reflection of light themselves and this is added to the color derived from transparency. Normal shading would have the local surface reflection "blended" with the color derived from transparency. What I mean by that is if the fog were actually transparent/opaque the way other surfaces are, it could block the light from behind. Poser atmosphere cannot block. It can "white out" but that's not the same as blocking or opacity. That just means you can no longer see the values being produced as they are clipped at 1.0 - "hypercolors" if you've followed some other discussions of this phenomenon.

The strength of the locally reflected light is in proportion to the Volume_Density. I do not know what the unit is here. When Volume_Density is 0, there is no fog.

The color of the locally reflected light is in Volume_Color. As is common with many shader things in Poser, it is therefore reasonable to assume that the rendered color is actually Volume_Color * Volume_Density, i.e. if things were named the same as other things, this should have been called Volume_Value, not Volume_Density, similar to Diffuse_Color/Value, Specular_Color/Value, Reflection_Color/Value, etc.

As you might have guessed, if Volume_Color is black (i.e. numerically 0) then there is no visible fog.

Rolling all this up, the equation I believe to be the underlying math is as follows:

Letting T be the color behind the fog, i.e. the transparency effect, each layer of atmosphere yields:

T + Diffuse(Volume_Color, Volume_Density)

In my shader, I modulated the Volume_Density. I used a P node to find the position of the fog plane currently being evaluated. Specifically, I used the P.y value to find the height of it. The rest is simple math to make a linear gradient in Y with a unit-span of 4 inches. The reference value is 25 inches + 5 * Clouds, which means there's some variation in density based on height. You get a little puffiness, which is more realistic.

I also modulated the Volume_Stepsize. I did that so the virtual fog planes are no longer parallel. Basically, I applied some randomized "displacement" to the fog planes by modulating their spacing, also using the same clouds node. This helps break up the fog planes and make them less easily detected by the eye.

Did another experiment. The Volume_StepSize changes when you select different Poser Display Units. So it is in PDU, but the value is not the spacing between the planes. Looks like about 1/4 of the value is used to space the planes. When I put .1 PNU or 10.32 inches, and render with a prop of that size, the prop seems to span four fog planes.

Just when you thought Doc wasn't looking ... :biggrin:

Quote - Did another experiment. The Volume_StepSize changes when you select different Poser Display Units. So it is in PDU, but the value is not the spacing between the planes. Looks like about 1/4 of the value is used to space the planes. When I put **.**1 PNU or 10.32 inches, and render with a prop of that size, the prop seems to span four fog planes.

Hmmm ........... 0.1 Pnu = ~10 inches
Looks AWFULLY close to 10 DGS inches, n'est pas?  :lol:
Sorry Bags ... couldn't resist.

Heheh, Geep.

Some peeps* just don't know when to quit, do they Bill? :lol:
Glad you took it in the spirit in which it was given.
You do excellent work and are a real credit to the community here at R'osity.
Thanks.

• like Dr Geep

cheers,
dr geep
;=]

I realize this comes in a little late, but have you found the parameter or setting(s) that wil ladjust the height(y axis) of the fog?

In my screen shot Mar 21, 2009, 4:13 pm, I marked where you control the height and variation in height. Does it require more explanation?

Not at all, I just didn't bother to THINK as usual. :scared:

Sorry to re-visit this old thread, but I was wondering if it's possible to make this fog "glow-in-the-dark"?

This is what I've got now, along with my settings (Poser 7)

I am not aware of a way to make the volume become self lit, requiring no light source at all.

However, glowing is perceived as emitting more light than arrives. All we have to do is make it blast out a lot more than the the light that reaches it. So then you could turn the lights way down and turn the volume way up.

Here's how - just plug a Math node into Volume_Color, and put a number bigger than 1. If you want it to be 100 times brighter than the light would normally produce, put 100 in there.

After posting this, I noticed that there are shadows from the figures affecting the fog luminance. If you're using this technique for low light trigerring a glow, you may want to disable shadows.

This is kind of a nifty trick if you want fog in real low light settings.

I need to try this with the envsphere

Hmmm apparantly this does not work with the envsphere setup.

Does it need a specific light not in the default envsphere lighting?

(I have one infinite light, and the ibl from the envsphere.)

Also, what do you change on the envsphere to keep the light from it, but not have the sphere render as the background?

(Probably a stupid noob question)

Quote - Hmmm apparantly this does not work with the envsphere setup.

Does it need a specific light not in the default envsphere lighting?

(I have one infinite light, and the ibl from the envsphere.)

Also, what do you change on the envsphere to keep the light from it, but not have the sphere render as the background?

(Probably a stupid noob question)

I'm happy to not be the only one who want to know how to obtain this. :)

I'm actually getting it to work after perusing BB's descriptions. I'm getting th fog how I want, and am experimenting with the height.

The only thing I'm seeing is the fog at 100% on the envsphere with very little top grading.

I'm sure there must be a way to use the envsphere for lighting but not have it in the final render, but haven't figured out that magic combination yet.

BB's numbers captured were for standard units, not poser native units, so some of the numbers have to be dialed down as a result.

Once I have something that looks right, I'll post the image results. I need to go over the env sphere thread, and find out how to use it properly for lighting but not for background.

I'm going to reset the scene though and try again, because I don't think I'm getting ibl lighting from the envsphere. if I remove all lights, the envspere does not light the scene at all. The rendered scene is supposedly with the envsphere with a image for the light, and one infinite light.

Ok, more testing, and apparantly ibl lighting from envsphere does NOT provide light so atmosphere shows up. You must have a light in the scene. I suppose you could fake it though plugging the same ibl image used for the sphere into the light color and brightness though.

Hopefully BB will read these new comments and reply back.

It doesn't appear that poser atmosphere reacts at all to idl.

So you can either use the envsphere and its light, and not have atmosphere, or you can add additional lights for atmosphere effects.

I would think that atmosphere would react to idl lighting, but I'l be hanged if I can get it to work.

Maybe BB has more voodoo magic up his sleeves for this?

The setting for invisible light emitter (i.e. envsphere supplies light but you can't see it) is in Properties: Visible in Camera=off. This is a new property introduced in P9/PP2012.

Re Atmosphere lit by indirect light, I imagine SM has said nothing about it and done nothing about it to make it work.

It could be an oversight that they were not aware of till now. I'll submit a bug report ticket, and see if I get any bytes on it.

Well, you don't have to use that. You can use actual geometry.

Here I experimented with some parallel (with the ground) planes and a nice shader.

What do you think?

Oh, it is lit by one infinite but, being a prop, it can be lit by IDL.

Spooky....

Quote - The volume atmosphere in Poser is just a handy convenience for procedurally creating a bunch of planes and then applying a transparency shader on them that ignores normals and just uses the amount of light as input to the shader.

Well, you don't have to use that. You can use actual geometry.

Here I experimented with some parallel (with the ground) planes and a nice shader.

What do you think?

Oh, it is lit by one infinite but, being a prop, it can be lit by IDL.

That might be worth including in your available envsphere downloadable goodies. If it works with IDL, you'd think that procedurally created planes would work as well.

Does the same atmosphere shader work with that, or did you cobble up something different?

I cobbled. I constructed my planes without UV mapping, and instead made each layer have a different V value. I took advantage of this to know where I am in the stack, instead of using a P node. It made things easier because then I could scale the height of the stack and not have to change the shader.

I dunno....that sounds like some of that BB voodoo magic trickery again to me!

How many layers did you make, and did you save the prop with its material? I'd like to tinker with this.

It looks very tiled to me.

The ground has a tile texture on it, under the fog, so you can see what the fog prevents you from seeing.

Doh! I should have known better, looks good then.

Can you upload your fog for download, BB?

I will when I have time. I'm working 13 hours a day and not at home.

Completely understand. Remeber to take some downtime for yourself as well!

Hey BB.. any chance of you uploading your ground fog prop before you forget how it worked or where everything is?

I'm on it. I was looking for it yesterday to upload it but I couldn't remember the file name. LOL

I really don't keep stuff anymore - too much to keep.

Remove the .txt extension. Inside is a prop and a PNG - drop it into a runtime of your choice.

The material should be pretty straightforward. The Clouds node literally runs it.

Remember, the planes are mapped V = 0 for the bottom plane, and V=1 for the top plane. Don't try to use images with them - they won't work.

This is not a UV mapping I would choose if Poser properly supported UVW mapping - I'd use W. But I can't.

I use the V value to make a gradient in brightness, and to change the density.