Hi

I have a campfire and a person sitting in front of it.

I want the scene to be dark with only what looks like the campfire lighting up the face of the person sitting near it.

Any suggestions appreciated

Thanks

Depends on what version of Poser you're running - with P6 or later, try starting with a point light positioned where the fire is. Turn off shadow casting for the flames, of course.

There's a prop freebie, a primitive sphere with lights attached north/south/east/west and the inbetween points. You can place the sphere in the fire, make it invisible, change the colours/intensities of the lights as required (or turn them off as needed) and point them towards your people. It's a really useful prop for adding atmospheres.

I think it's called lightball or something, I'm at work so can't check my runtime.

Edit: it's called Globall - do a search on www.whatever3d.com and hit the picture to get the download.

Purrdey,  I have something similar to that prop but it's called **Globall Cast-light Simulator.
** I don't  know if that's what you mean.

Hope this helps...

Probably is. I'm sure it's really simple to make it yourself with a primitive and parent the lights but I'm notoriously lazy ;)

This was the pic that I was thinking of when I read the question about getting the glow from the fire as I wanted to get the same effect from the smoke here. I used it here to get the green glow coming out of the sarcophogus:
http://entertainment.webshots.com/photo/2358809000017395510QOiivD?vhost=entertainment
(the smoke is postwork in cs2)

Quote -

Edit: it's called Globall - do a search on www.whatever3d.com and hit the picture to get the download.

You can find it in the free stuff area here. It's by SnowSultan

http://www.renderosity.com/mod/freestuff/index.php?user_id=856&page=2

Thanks Acadia, I always wondered who was the wonderful helpful person that made this useful prop.

I don't get all this talk of props and parented lights. He's not modeling a lighting fixture. EnglishBob gave the right answer in the first response.

Use a point light. Make it yellow. Put it near the fire. Done.

The nifty thing is you can have lights pointing in all directions from one invisible sphere just as you would have a sphere of light emanating from a fire.  You just move the sphere around and all the lights follow - much easier than trying to move 8 lights around. If you look at the product available here which comes with fire props and lights, that is exactly how it is done.

If you just use a point light, make it yellow and it works then fine, fair enough, that works and yes done. I didn't realise that there was a right/wrong answer. I was suggesting something that may work better than a simple point light - and it's free so if it doesn't work then nothing lost.

Bagginsbill,  your suggestion, while simple, does not offer a sense of realism to the render if that is what person is going after. It like the VSS system... 1 point light doesn't give the sense of realism that your setup gives... (BTW, I'm in love with your shader setup... UBSS and VSS!  You have spoiled me, sir!!! :ohmy:)

I hear what you guys are saying, but what I'm asking is why does realism demand that a fire throws different colors of light in different directions. Does it?

And as for true realism, what's really missing from these types of lighting situations, however you do them, is inverse square falloff. Search for that and you'll see a post here where I showed how to make lights in Poser do that. If you don't implement that, you will never get realism when you're talking about lights that are only a few feet away from people around a camp fire. The figures that are closer should be more brightly lit. You can do that with Poser's linear distance falloff, but that is not physically accurate. That will make the light go to 0 at some distance. Light doesn't do that.

Thanks, Babbinsbill.  Will looks for that and do that... In the meantime, I have research your input into ghost shaders and what's not. Interesting reading and what with Halloween around the corner (2 months and it's my bd) this would be the puuurrrrrrrrrrrrrfect time for me to start working on something Halloweeny.

Is anybody going to tell me why fire should throw multiple colors in different directions, and so cannot be simulated with a point light?

Is anybody going to show me a render?

Quote - I don't get all this talk of props and parented lights. He's not modeling a lighting fixture. EnglishBob gave the right answer in the first response.

Use a point light. Make it yellow. Put it near the fire. Done.

Yes, that works great! I did that for this for the candles in this image

Unforgiven II

@bagginsbill:
For many fires, a single point light might give reasonable appearing illumination of nearby figures.
However, there are circumstances (i.e. big fires) where the flames are quite tall and you will see a distinct variation in luminance and flame colour from the heart of the fire (where the fuel is being broken down by pyrolysis) to the tips of the flames (where the vaporized fuel has just about all been burnt and the flame temperatures have dropped so that the gasses are not glowing so strongly). Even where the flames are mostly uniform in colour, the flame density tends to taper off with height - hence the luminance will change with height.
If the flames are significant in height compared to the figures (and they are quite close to the fire), then there should be a corresponding variation in the colour and degree of illumination too.
A wood or coal fire also tends to have a lot of less bright red-glowing embers in the base of the fire compared to the often oranges or brighter yellows of the flames. Furthermore the illumination from a fire is often highly non-uniform with complex partial shadows/bright spots caused by the solid fuel and/or flames and/or smoke.
e.g.: Photo showing some of the variations in colour and luminance:
http://pixdaus.com/pics/1210046743BYpAfLq.jpg
also, check out Romanceworks' "Ultimate Fire" which shows how non-uniform the fire can be (warning nudity in this link):
http://www.renderosity.com/mod/bcs/index.php?ViewImage=15547

So, I don't think that there is a "one size fits all" solution - especially for bigger fires.

If colour transmittance could be handled in Poser, then I guess you could use a single white point light with a graded (low = red to high = yellow) and irregularly shaded (i.e. using dark er and lighter patterns) spherical filter around a white point light.
Regards,
Jovial.

Good points, but I'd say for a tall fire, you should use two or more pointlights in various positions, with various colors, then.

Ignoring the color issue, for a really large fire you'd need light coming from above and below.

But even a big fire like this one

• you have to show me how the point light isn't going to work. The most important thing as I said is that you do inverse square falloff.

I wasn't really objecting to the notion of multiple lights, but rather that parenting them to a prop and pointing spotlights in various directions is not relevent.

Shall I do some renders?

Quote - Shall I do some renders?

Oh, go on then. You know you want to. :-)

I too, wish to see some renders. It's been a problem that I've struggled with for a long time and it would be interesting to see how you approached a solution. I'm still using Poser4, so I hope it will work. thanks ; )

Yes in Poser 4 you don't have point lights, right?

Just infinite lights and spotlights - and no material room to do clever stuff in either. How did we ever manage?

EnglishBob... Just like we did with Poser 2... with great difficulty...:lol:

Correct, no Point Lights. :(

So here is my render, using exactly one point light with the inverse square falloff applied, and gamma correction. No postwork - this is a straight render out of Poser.

Click for full size.

I'd like to know how to do the inverse square thing, if you have the opportunity to post the settings some time. That looks very convincing - could be useful for other "in-scene" light sources too, I'm thinking. 

Here's another render, with an additional figure closer to the fire, demonstrating the Inverse Square Falloff (ISF) not only darkens with distance, but lightens with nearness.

Hang on a sec and I'll upload a bunch of screen shots showing how I did all this.

(Note: The Scale is not important. I scaled the light up so in preview I could see the little light-orb better.)

On a point light, the rotation transforms are irrelevent. All that really matters here is the Red, Green, Blue values, the Intensity, and the XYZ translation (position).

When you move the light, you need to take note of those coordinates. Also, my shader is ISF shader is set up for inches, so set your Poser Display unit to inches before you read off the numbers.

I'm using Ray Trace shadows, with a blur of 7 and min bias of .2. I think the units of blur are degrees, but I'm not sure. If they are, then that is a 7 degree blur cone. This looks pretty good for a fire, but you can adjust it as you need to. If the fire is really huge, it should probably be bigger. WARNING: Render times go up with increasing blur radius.

I suggest for test renders (where you are adjusting light levels) you don't bother with shadows. Goes much faster.

Don't forget to enable ray-tracing when using RT shadows.

The first tree is a real 3D prop. The second tree is just a one-sided square with an image and a transmap.

For the barrel, I just used a Poser cylinder.

For the fire, I used a one-sided square and a photo of fire from free stuff. The fire didn't have a transmap, but I was able to create one dynamically with nodes. I'll show the shader for that.

The fire photo was of fire in a barrel, and it took me some time to line up the photo with my actual 3D barrel. Once it was right, I was REAL careful not to move my camera. I only used Focal length to adjust things, which retains the perspective overlay of the fire photo against the cylinder.

Look closely above the barrel, just to the left of Simon #4's hand. That is my point light. I did that position so that the barrel would block some of the light hitting the ground. If you raise the point light, then the barrel's shadow will be smaller.

After positioning the light, I took note that the XYZ position (translation dials) was 0, 50, 0 IN INCHES.

The preview does a pretty good job of showing me how the light is going to be thrown on the figures and props. But it does NOT show the falloff, as that is being handled by a shader, and Poser doesn't evaluate light shaders in preview. (At least it doesn't for me.)

Then I ran that into a Bias, to shift the mid tones brighter. The result (Math_Functions_2) shows the dynamically created transmap. Neat huh?

On the top right, there is a Math:Pow function with Value_1 = 30. This value is your "reference distance". This is what it means: as the light moves away from the source, at what distance is the intensity exactly 1 times your dial setting? I entered 30. This means that my light will be exactly at the dialed Intensity (1.0 in this case) at that distance from the point light. Anything closer than that will be brighter than the dialed intensity. Anything farther will be darker.

The reference distance needs to be squared, so I have it in a Math:Pow node with Value_2 = 2, thus it is distance ^ 2.

Now the coordinates of the light need to be entered in the User_Defined node. Red,Green,Blue corresponds with X, Y, Z. My position was 0, 50, 0. If you move the light, just enter the new coordinates.

The P node delivers the position of the rendered point, in units of 1/10 of an inch. (Why I don't know. Strange choice.) By setting the P node factors to .1, I convert those coordinates to inches exactly.

The Color_Math:Subtract node is finding the difference in xyz position between the light coordinates and the rendered point coordinates. (This is why units matter - gotta pick a unit and go with that. If you subtract inches from meters or whatever, it's all screwed up.)

The Color_Math:Multiply squares each of those values. So now we have dx^2, dy^2, dz^2. (dx is delta x, dy is delta y, etc.)

Finally there is a Math:Divide. This computes the ratio of the reference distance and the measured distance, squared. (  thus it is d^2 / r^2). Whend d=r, this is 1. See?

Note: I had to use 3 times the delta. This seems strange, right? Well the reason is simple. When you plug a color into a number, Poser averages the three values, i.e. it is (x ^2 + y^2 + z^2)  / 3. Since I actually want the x^2+y^2+z^2, I multiply by 3 and that business gets canceled out.

So the output of the divide node is the proportional light intensity at the rendered point. Plugging that into my Light Intensity gives me my final value.

However, if you have any earlier versions of Poser, there is a bug we must deal with.

The User_Defined node mistakenly does something wrong with your RGB values that you type in. To get around that, you have to use this version of the ISF shader.

Instead of typing the coordinates directly into the User_Defined node, you have to connect three more math nodes, and type your coordinates in those.

As you see here, I put 0, 50, 0 in those three nodes. The result is the same, but it's a little more node work, and less convenient.

If you have the newer versions of Poser, you don't need to use this one.

That's it. Questions?

Show me your renders!

Interesting about the need to have inverse squared vs just linear falloff. 
Here is a simple scene with a cone, a sphere, the ground plane and
a point light embedded in another semi-transparent sphere.

What  a difference, eh? The linear falloff goes to 0. That's just wrong. Light intensity never goes to 0. It just gets closer and closer to 0 forever.

Notice also how your glow sphere is glowing more intensely because it is very close to the light source - just like real life. Even a dim bulb is very bright when you look right at it.

I used two point lights.

#1: 50 inches above the ground, orange, 20% intensity at 100 inches distance.
#2: 200 inches above the ground, red, 75% intensity at 100 inches distance.

If you only use one light, you get shadows where you shouldn't. The two lights here produces the proper shading depending on whether a surface faces up, down, or horizontal. It also makes high things more red and low things more orange.

I don't think adding any more lights would make any appreciable difference.

I'll second that ^^^

just to confirm a couple of points though...

The inverse square doobrie.. that's the math function a couple of posts up right?

And I only have to apply that to my point light to get it to work? You are a clever bunny.

And the square for the fire... does that NEED to be a one sided square? I used a hi res one and am having to light it from the front to get it to look bright - if I use a one sided one will it take light from the back too?

:edit:

By the way, I'm doing this as I'm going along, trying different things, I just want to know if I'm on the right track... this PC doesn't exactly render at the speed of lightning lol

I guess this constitutes as another great tutorial be the Honorable BB.  Thanks for enlightening us.

i am having some problems. i just dont get it. i dont have SP3 so used the right shader

you said we need to change the settings to inches. this also goes for the position numbers right? 
i thinks this is the reason why it looks strange. it was set to feet. and when i typed x,y and z it was not correct

can we use those stetings also for infinite lights ? will it change even?

Sorry to bring this up from a year ago but it's good stuff... Quick question...

With regards the point light shader, under Poser 8 (not sure if it was there in previous), for the light materials, I get Preview, lampFlaps and lampBase.

Against which material is the shader to be applied...?

Are you sure you are selecting a point light?  Those features exist with spot lights.  Point lighting emit a 360 degree illuminations while you can control spot lighting spread, distance and direction.

Poser 8? You don't need this shader for Poser 8. They built this shader into the lights in Poser 8. Just set the light to inverse square falloff.

Quote - Just set the light to inverse square falloff.

Can you help the blind, not seeing this?