When showing something on a surface or floor, a lot of realism is lost because we don't get nice soft "contact" shadows. Adding the Ambient_Occlusion node to your floor material will improve this dramatically.

The neat thing about using it on the material, instead of AO on the light, is that you can restrict this expensive operation to a subset of your scene items, and you get more control with regard to different parameters in different places, and also it just works better than Light based AO.

I've done a bunch of experiments with regard to quality and render time. Knowing the following info will help you skip a lot of wasted time.

Setting Samples more than 3 is important. 4 is clearly better than 3 and not much slower. 5 is modestly better and not much slower. 10 is great but much slower. More than 10 is not worth it.

The MaxDist parameter controls how far the effect goes. I have no idea what the units of this parameter are. I find that 30 to 50 produces good results in most cases.

The Strength parameter seems to do nothing. 0, 1, .5, all produce the same results. No matter - the MaxDist parameter pretty much also controls the strength of the effect. Lower values produce less shadow.

In Poser 7, Irradiance Caching (render setting) will have an impact on quality and speed. Lower values are faster, and sometimes produce no loss of quality, depending on your geometry. IC 0 to 50 seems to produce pretty much identical results. Always try a low IC for speed first - if the results are good, you're done. Sometimes, though, the maximum value is necessary for quality, but you get a huge increase in render time. Note that if you type in 100, it often resets to 99 or 98 - wierd. Ignore that. It works.

I've attached two renders to demonstrate. I was messing about with refining my leather shading techniques, and was unhappy with the final render, on the left. It still looked fake. Adding AO to the ground, I rendered again. The shoe pixels are identical, yet the second render looks more real! It's in the shadows baby.

On the bottom is a screen shot of how to wire the node into your shader. Just plug it into the Diffuse_Value. My render actually used a MaxDist=500, which produced a much broader darkening. This made the shadow go beyond a simple contact shadow, but I liked the effect.

Click the image to see it full size.

Oh hey I just discovered another thing. The MaxDist parameter changes if you alter your Poser Display Units. This means that the number you should use will depend on your Display Units setting. My units are always inches. So 50 is 50 inches (although clearly it doesn't actually go that far, more like 5 inches.)

So if you're using centimeters, my 50 is your 127 (roughly). If you're using Poser Native Units, my 50 is your .484496.

Yay you're here today and we get to have a material room discussion. Excellent!

a little more info

Poser 7 has a "Set Up Ambient Occlusion" wacro in the material room that will automatically add the AO node and plug it into your Diffuse_Value and Specular_Value of your current material.

Occlusion Master is a wacro avaiable here (i believe from Face_off) that will let you set up and adjust  an AO node on mutliple materials of the current figure/prop.

and thank you Bagginsbill for the explanation. Keep up the good work

Nice one, BB.  Karen suggested I use the technique on one of my pics so it's nice to have a practical demostration.

Don't use that wacro. It should not attach AO to the Specular_Value. Specular reflections simulate the direct bouncing of light from the light source to the camera. Such light beams are not ambient at all, but are direct illumination from a particular spot, reflected towards the eye. The presence of nearby objects does not stop a specular reflection in real life, unless they are directly in the path of the beam. In other words, ordinary shadows handle this correctly. So you shouldn't model that in your shader.

Imagine you have a shiny ball at the bottom of a coffee cup. You shine a spot light into the cup. Should you see a specular reflection on the ball? Yes you should, unless (and only unless) the rim of the cup blocks the light directly. If you suppress that specular with an AO node, it won't be real. The specular reflection is not coming from all over, so should not be decreased just because there are object nearby but not in the way.

Diffuse reflection, however, is a collection of light beams bounced from lots of different directions. So you do want to block the diffuse component of a shader using AO, so that it reacts properly to the presence of geometry nearby, in pretty much any direction.

My attached image demonstrates. First is without any AO. Second is with AO on Diffuse_Value of all cup, ball, and ground. Third is with AO on Diffuse_Value and Specular_Value. Notice how much the ball's specular is supressed. This is wrong. It's hard to notice, but the specular on the lower part of the cup handle has also been modified slightly by the AO - this is not realistic.

If I posed a character's hand near the cup handle, the speculars would go away, even if the hand does not block the spotlight.

In the attached image, I show how to make your own strength for the AO. Plug the AO into a Blender as shown, and adjust the darkest shadow you want by changing the Input_1 value to an appropriate shade of gray.

Quote - Don't use that wacro. It should not attach AO to the Specular_Value. Specular reflections simulate the direct bouncing of light from the light source to the camera.

Good to know. although most products that i have run across, the Specular_Color is set to black so it would not make any diffrence.

Now the cup is red where the ball is causing AO.

Unfortunately, we're also getting red AO on the outside of the cup. The way to handle that is to edit the cup's material zones, using the Group tool, so that there is an inside material and an outside material. You'd then be able to use the gray+red only on the inside, leaving the outside still plain gray.

Well, darn! I just finished a render where I thought that while things were sitting on the floor they looked "pasted" there and planned on using the "darken tool" in post work to fix it. Now I come here and see this! I think I'll take another 3 hours and do another render,  LOL

hugs

I have a question.

I put a cloth plain into a box and added a texture to it that looks like a rich top soil.

However when I render it looks like a flat plane that is textured like top soil, LOL   There doesn't seem to be any "interaction" with the box at all IE: the shadows which are visible in your coffee cup/ball example.  I don't have that effect and the result is pretty flat and unreal looking.

Hey BB.. just had a question/thought... What's the best node setup to use an image as background? I'm sure you prolly have a trick or two up your sleeve about that setup.

Wouldn't a good default load setup have the ao applied on the ground plane, and a graphic backdrop with whatever node mojo you'd have for it?

Granted, no two renders are the same, but a good starting point would be useful.

Hmmm..... can a node setup be done for a proceedural gradiant "sky" effect? (I lightwave, you can define the highest sky point as one color, the bottom most as another color, and adjust the blend point with a setting. Maybe a sky gradiant like that could be setup in poser, with a number of gradiant colors, so you could simulate, say  a sunset "sky"? That could possibly even be hooked into somehow as additional base sky "lighting" of objects?

The moon thing got me wondering is a gradiant could be setup for the sky, rather then loading a prop, and faking a gradiant sky with that.

Quote - I have a question.

I put a cloth plain into a box and added a texture to it that looks like a rich top soil.

However when I render it looks like a flat plane that is textured like top soil, LOL   There doesn't seem to be any "interaction" with the box at all IE: the shadows which are visible in your coffee cup/ball example.  I don't have that effect and the result is pretty flat and unreal looking.

Put the AO node on the dirt's Diffuse_Value just like I showed. The AO node will darken whatever it is on, based on other things being nearby.

Quote - Here is an image of what I mean. How  would I go about getting that nice shadowed edge without the shine on the soil. Do I attach the AO node to the casket or the cloth plane? I'm a bit confused about where to put it when it's not "ground"

The soil is shiny?!? Do you have specular on it?

You probably also want to put the AO node on the casket too. It will do the right thing.

I don't have a casket. Where can I get one? Free stuff? I'll go look.

Quote - Hey BB.. just had a question/thought... What's the best node setup to use an image as background? I'm sure you prolly have a trick or two up your sleeve about that setup.

Wouldn't a good default load setup have the ao applied on the ground plane, and a graphic backdrop with whatever node mojo you'd have for it?

Granted, no two renders are the same, but a good starting point would be useful.

Hmmm..... can a node setup be done for a proceedural gradiant "sky" effect? (I lightwave, you can define the highest sky point as one color, the bottom most as another color, and adjust the blend point with a setting. Maybe a sky gradiant like that could be setup in poser, with a number of gradiant colors, so you could simulate, say  a sunset "sky"? That could possibly even be hooked into somehow as additional base sky "lighting" of objects?

The moon thing got me wondering is a gradiant could be setup for the sky, rather then loading a prop, and faking a gradiant sky with that.

For an image on a background, load a one sided square. Set Diffuse_Value = 0, Specular_Value = 0. Attach your image to Alternate_Diffuse. Done.

Yeah its probably a good idea to configure your ground plane to have an AO node by default, and save that as your default scene.

As for gradient sky - sure - I do it all the time. In my default scene, I have a giant sphere. I load any gradient I want using nodes. We need a new thread for this. I'll be back.

As for using the environment sphere for lighting as well, you need to have an image for the sphere in panoramic format, and also an Angular Map conversion of that image for your IBL. I discussed this in a few other threads over the last couple weeks.

Quote - > Quote - Here is an image of what I mean. How  would I go about getting that nice shadowed edge without the shine on the soil. Do I attach the AO node to the casket or the cloth plane? I'm a bit confused about where to put it when it's not "ground"

 

The soil is shiny?!? Do you have specular on it?

You probably also want to put the AO node on the casket too. It will do the right thing.

I don't have a casket. Where can I get one? Free stuff? I'll go look.

No, sorry.  I was trying to hurry up and type because someone was waiting at my door,  LOL  that will teach me ;)

The soil isn't shiney. What I meant was without the shine that is on the ball in your image examples.

Quote - Put the AO node on the dirt's Diffuse_Value just like I showed. The AO node will darken whatever it is on, based on other things being nearby.

Ok, that seems pretty clear. I'm going to give that a try not only on the soil but a few other items in the scene that look "flat" too and see how it goes. Thanks :)

Quote - You probably also want to put the AO node on the casket too. It will do the right thing.

I don't have a casket. Where can I get one? Free stuff? I'll go look.

The coffin is by adp001

http://www.sharecg.com/pf/adp__

I will send you a link to my dirt texture.

I figured you could use a loaded sphere for a gradiant sky, but isn't there some way that could be done node wise with the background, so transparency is retained for postwork?

Ah - I'm downloading it now. But meanwhile, I found some random box which i scaled up. I also found some random dirt texture which i put on a one-sided square inside the box. I'll show you the material I did for the dirt. I added some displacement so it looks less flat, in addition to doing the AO on it and the box and the ground.

I put a Poser Hi-res sphere in to give you a sense of scale. I'd use a figure but that will make my test renders long - i'm trying to go fast.

Here's my box of dirt without AO. Click for full size.

Quote - I figured you could use a loaded sphere for a gradiant sky, but isn't there some way that could be done node wise with the background, so transparency is retained for postwork?

I'm confused by that seeming contradiction. Either the background pixels are filled or they're not filled. How would you expect the sky to render but still be transparent?

If you intend to composite your figure onto a background in postwork, why would you want it to render a background?

Compositing with a sphere or a background square is going to fill every pixel and give you the background you want without any postwork, right? Why would you want to composite that with something else?

The AO one looks so much better because it now has some dimension to it.

One more question. I notice that you have the diffuse_value set to .3.  When using the AO node do you always want a lower than 1.0 value?  Everything I'm wanting to use this on currently has diffuse_value = 1.0  and when I change it to 0.3 the object becomes very dark in preview. Haven't rendered to see what it looks like yet, but it's really dark in preview.

There's a common habit among people to always use a Diffuse_Value = 1, but I don't think that's a good idea. It limits your options and tends to make things too bright. It makes it hard to adjust the speculars in a realistic way. Nothing in the real world does 100% diffuse reflection of the incoming light. So get used to using lower numbers. However, in the end, the Diffuse_Value times the Diffuse_Color gives you two ways to lighten or darken something, in addition to actually raising or lowering your light intensities.

Meanwhile...

I got the coffin and your dirt. Nice coffin. I slapped some old wood texture on it. Here is the render without AO.

I noticed that the lid is UV mapped stupidly. It repeated my texture. Oh well.

bill, thanks for the discussion of the AO node. irradiance caching is restricted to less than 100% due to its corresponding variable in the render properties called maxError (see poserpython methods manual). since maxError > 0, and since IC = 100*(1 - maxError), IC can't be 100%. apparently, trying to set maxError to 0 would require an infinite number of calculations per pixel for that part of the rendering calculation, similar to trying to set shading rate to 0 in all object properties as well as in the render settings.

OMG! That looks spectacular!!

I understand. The peculiar thing is why the programmer who added the widget told it the max value is 100. When you slide it with the mouse, it shows 100, then when you let go, it always pops back to 99. If it properly only went to 99, I never would have mentioned it. :)

Also, if you're typing, you must type 100 in order to get 99. If you type 99, you get 98. :)

Quote - > Quote - I figured you could use a loaded sphere for a gradiant sky, but isn't there some way that could be done node wise with the background, so transparency is retained for postwork?

 

I'm confused by that seeming contradiction. Either the background pixels are filled or they're not filled. How would you expect the sky to render but still be transparent?

i think Gareee was asking for a material to plug into the "background" that would give a horizion/gradient in the render.
the transparency is maintained in saving a tif or png because the "background" that renders in poser is considered by poser as transparent because there isn't any geometry.

what i have come up with so far will give a gradient, but won't simulate a horizion. I use the v texture coord, a few math functions and a blender.

Yea that's how you make a gradient for "Background", a one sided square, or a sphere.

k = (V - bottom_of_gradient) / (top_of_gradient - bottom_of_gradient)
Blend(color1, color2, k)

You can also rotate the gradient up to 90 degrees by using Blend(U, V, rotation) instead of V. For full rotation, you can use trigonometry.

But as you point out, doing this on the "Background" is not 3D - it is 2D. There is no way to make the gradient obey 3D perspective as you move the camera around.

And I still don't get the point. We can use nodes to fill the "Background" with anything we want, but if you save with transparency, you pretty much have completely discarded it, right? Why bother programming a background if you're going to ignore it in post?

Also, for Gareee's moon, if we use the transparency version of the moon shader that I made, so that it reveals the background instead of drawing the dark side of the moon as black, it too will be discarded when you save with transparency.

This was just the thing my render needed! It now has some depth and doesn't look like things are flat and "floating"

Thank you so much for starting this thread.

I also learned about "fractal sum" node which I like!

While it would discard it if you ONLY used the main alpha image, you could still add that in a layer n photoshop, and adjust another layer using the background render as well.

I usually use a gradiant of some kind in my renders in the background, but almost alwaysdo them in photoshop, just because it's what I've used for years on end.

Just looking for poser centric options, and thinking about options and possibilites.

Bagginsbill,

Thank you for these little tutes on AO and  your postings on HDRI.  Following your threads over the last few weeks have improved my understanding of lighting and nodes no end. I have finally been able to get the look to my renders that I have been after for so long.

EF, should give you a Job. this is where this community Really SHINES.

Again,

Many thanks, Nick.

So as a beginner, what wouldn't I want to put ambient occlusion on? Will it work on skin, hair, eyeballs? Or is it really only good on flat surfaces?

It's a question of bang for the buck. Because it really slows things down, if you put it everywhere, even if nothing is nearby, it still is expensive for it to figure out that nothing is nearby, and therefore there's no reason to darken the object.

So you should look around at things that are near each other and ask yourself if you need a contact shadow there. A hand always needs it for realism on the skin, because the fingers are close together. But a naked back doesn't need it if there's nothing nearby. So you'd put AO on the hand but not on the torso, if the pose was right.

Another thing you'd not bother with is if you had a wall behind your figure and nothing near it. It's a huge waste of time to calculate AO on the wall for a big part of your scene if it's not going to do anything. But! Put two walls together in a corner which you are including in the view, and you should be using AO.

In general, all objects in real life get darker when something else gets nearby, and starts blocking some of the ambient light in the room. So the general answer, ignoring performance, is to always use it.

Quote - And I still don't get the point. We can use nodes to fill the "Background" with anything we want, but if you save with transparency, you pretty much have completely discarded it, right? Why bother programming a background if you're going to ignore it in post?

Correct me if I'm wrong, but doesn't background affect the edge pixels in a tranparent png? I've gotten different results in the past when I've rendered over the default gray, vs. over black, vs. over a background image or background color. Yes, the pixels are partially transparent, but wouldn't the matte color that affects that transparency change based on your settings? Especially with items that have a high transparency or translucence.

I need to do some tests to try it out, but when you affect the background, even if you're exporting with transparency, I would assume you'd get different results. And then when you composite later (for example, if you need to composite many elements into one image that would be a pain to render all together), you don't get some halo effect or an unrealistic transparency. Is that incorrect?

You're correct - the blending of semi-transparent or edge pixels will be influenced by the background. For perfect post-compositing, the background should be rendered black. Then the true background (or other overlapping objects) will be correctly blended into those pixels in your post-compositing tool, such as Photoshop.

The blending formula is this:

Blend(back, fore, alpha) = (1 - alpha) * back + alpha * fore

Where I'm denoting back = background color, fore = foreground color (from your object), and alpha is the alpha channel value for the pixel, or in other words the opacity. Opacity is 1 - Transparency, FYI. The color values stored in the PNG file are the result of doing this Blending step. In addition, the alpha value is recorded.

If you follow through with the math of doing a blend with BLACK, you'll see this does not add anything to the color. A second Blend operation (done in Photoshop for example) will pick up the pure color of your object from Poser. But if you blend in poser with other than black, then some of that will be in the file, and mix with your object's color when you blend it in Photoshop.

I'm just saying I don't get the point of rendering a gradient background if you intend to composite outside Poser. Not only will you be discarding it, but it will erroneously color your fringe pixels.

Guess that kinda makes sense... I just want my cake and to eat it to!

Hmmm... we had a GREAT lunch today on a mountain top restraunt, and the desert was SO big I couldn't eat 1/3rd of it (and I CAN eat chocolate cake all day long!)

Guess I need to grab that doggie bag and much some again... ;)

Quote - I understand. The peculiar thing is why the programmer who added the widget told it the max value is 100. When you slide it with the mouse, it shows 100, then when you let go, it always pops back to 99. If it properly only went to 99, I never would have mentioned it. :)

Also, if you're typing, you must type 100 in order to get 99. If you type 99, you get 98. :)

Wild guess here, but how many programmers do you know that have a specified range of 1-100 but insist on programming the zero point as...well..zero, but make a 1-100 GUI?

Been there, done that, designed the T-Shirt.  Trouble is, the T-Shirt only had one sleeve. ~lol~

Attached Link: http://www.renderosity.com/mod/gallery/index.php?image_id=1548818

MOST excellent!

how do you add AO to diffuse value when something else is already there connected?

Quote - I just came across this post; and your tip for reallism in our renders was great.
So I thought you might like to see what I came up with...
http://www.renderosity.com/mod/gallery/index.php?image_id=1548818

Nice image. The figure looks very good. I can see the AO on the figure and the shoes, but I didn't see contact shadows on the ground under the shoes, and I didn't see any kind of shadow at all for the lipstick. Perhaps I'm not seeing clearly this morning. I'm just curious about how that happened, if I'm seeing correctly. Was there AO on the ground?

It would be educational if you could post here a (reduced size) side-by-side with/without AO comparison. This is a subtle effect and I think a lot of people don't even realize what they're missing. Tell us what settings you used, too. I find that choosing parameters for nodes is always tricky and if we all share demos and values then we can all save a lot of time. Knowing ahead of time what a setup is going to do is a huge benefit. I can't tell you how much I enjoy Poser more now than I did in the beginning because now I know what I'm going to get without a lot of test rendering.

Really nice image - thanks for showing.

Quote - how do you add AO to diffuse value when something else is already there connected?

Simple - use a Math:Multiply node to combine them.

Suppose you already had Diffuse_Value = X -> Y. (I'm using the symbol -> to indicate a channel connected to another node. The X indicates the numeric or color value in the channel, and Y indicates the connected node) So now you do:

Diffuse_Value = 1 -> Math_Functions:Multiply(X -> Y, 1 -> AO)

The X in this case would be the original numerical value that is in the Diffuse_Value input. You need to move that to the Multiply node, and then change it to a 1.

Very nice!  Ironically though I had a similar idea in my "one day to do image list" which I have just now crossed out because you beat me too it,  LOL Anyway, since we're showing off AO results, here is mine!  I used the AO node on the coffin, the dirt, the ground, Michael's hair and pants (to try and improve the look of the waist band area by the body). Though it didn't really seem to make a difference with the pants at the waist.

http://www.renderosity.com/mod/gallery/index.php?image_id=1548180

I also used bagginsbill's candle shader which is my absolute favourite shader!  The lights are my own concoction.

I've attached a full render of the image without the AO for comparison. Click for a larger view. You can see that  the AO makes things look "richer" in colour while the one without AO looks dull and less "dimensional".   I'm very impressed with this and will be making it a staple of all of my future images!

Bagginsbill also gave me some great advice for my "glowing hair", hehe.  I had rewired the nodes so that the Diffuse Colour Node was in the "Alternate_Diffuse" node.  I'll let him explain the concept behind what I did and what he suggested as a better way :)