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Posted: 07 August 2012 07:16 AM   [ Ignore ]
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Okay, initially this will just be a “pull” of the other thread so that people can see all the images in question easily.  I won’t copy every post over, but I will try and incorporate the lessons learned in those discussions.

Index:
Journey 01: The Beginning:
- Ambient Mode
- Occlusion with Soft Shadows Mode
- Occlusion with Directional Shadows Mode
- IDL with Soft Shadows Mode
- IDL with Directional Shadows Mode
- Bounce Light (GI) Mode
Journey 02: Map Controls
- Saturation
- Contrast
- Mixing Experiments
- Final Thoughts on Saturation and Contrast
- Tangent Contrast vs. Intensity
Raytrace Settings
- Occlusion Strength
- IDL Strength
- Occlusion Color
Journey 03: Other Settings:
- Occlusion Samples
- Shadow Bias
- Shading Rate
- Max Error
- Maximum Trace Distance
Journey 04: Additional Comments / Questions from the Original Posts
- Using UE2 with Additional Lighting
- Why is IDL so slow?
- Things are still grainy?  How do I fix that?
- Map Color?  What does it do?
- I need help on basic lighting!  Help!?
- Environment Sphere appears offset when compared to sphere primitive?
- What about all those other parameters you haven’t covered?


————————————
Intro

Basically, it occurred to me after reading another thread on IBL (Image Based Lighting) that I, personally, don’t really understand UberEnvironment2 (UE2 hereafter) (included in DS3A and DS4A and higher) as well as I should.

So this thread, isn’t a tutorial. This thread is my journey of collecting what I DO know, what I think I know and trying to learn more.

The first thing I know? Well, I’ve already said it. There’s a lot about UE2 that I don’t know.

I also know that I can get some amazing results out of it but often there is a lot of trial and error and when I find something I like I tend to over use it causing much of the output of many of my renders to have a feeling of “uniformity” even if the content is quite different.

So here we are, chronicling my effort to learn more about UE2 and yes, this is pretty much how I learned almost every thing I know about DAZ Studio. Reading here, sharing here and good ol’ trial and error.

Please feel free to follow along, ask questions, make observations, correct my misunderstandings, etc. as I start this journey of a deeper understanding of UE2 in DAZ Studio. I will primarily be using DS3 for this, but everything still should apply for DS4 users.

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Posted: 07 August 2012 07:18 AM   [ Ignore ]   [ # 1 ]
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Journey 01: The Beginning

To start things off, what I’ve done is I put together a fairly simple scene. Most importantly though I created a ground plane. I wanted to see shadows and we’ve got to have something for shadows to land on. Then I tweaked the surface of the plane a little bit. I changed the specular color to 255 255 255 and the glossiness to 35%. I also reduced the Ambient strength to 0%. This gives me a slightly better pallet for shadows to land on and should not introduce much in the way of color influence over shadows / bouncing lights etc. I also created a sphere primitive and did basically the same thing, except I also changed the diffuse color on its surface to 255 0 0 (bright red). I did this to give some extra contrast. I probably should’ve used multiple primitives but that was boring so I added the Coalition Claymore suit to the ground so it’d be more entertaining.

The next thing I did was add UE2 to the scene, applied the Set HDR KHPark preset and then the 3 high quality preset.

Before I went any further, I thought, okay, well, let’s see what each of the various Environment Modes on UE2 do. So I’m going to go through them all and talk a little about each as I go.

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Posted: 07 August 2012 07:23 AM   [ Ignore ]   [ # 2 ]
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So the first mode I chose was, intentionally the most basic mode UE2 offers. “Ambient (No Ray Tracing)”. As one should gather from the name, this mode offers no shadows, no occlusion, nothing but an overall “ambient” light.

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Posted: 07 August 2012 07:23 AM   [ Ignore ]   [ # 3 ]
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Rendering the scene in this mode demonstrates that fairly clearly.


Total Rendering Time: 7.48 seconds

 

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Posted: 07 August 2012 07:24 AM   [ Ignore ]   [ # 4 ]
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Now, why might I use this mode? Well, it’s durn quick. But really, by itself it isn’t all that useful. The way I foresee using this mode would be at a greatly reduced intensity as a supplement to additional lighting. You could easily use it to provide “ambient light” for indoor scene which is notoriously difficult to do using traditional lighting. Perhaps even subtly shifting the light color towards a lighter gray or other color as my suit the needs of that individual scene.

It should be noted, however, that even in “Ambient Mode” because I have applied an Environment Map the light has become ambient AND directional. Look at the red sphere in the foreground. It should be fairly easy to see what impact the environment map has had on the way the light is cast over the scene. Were I to rotate the UE2 object, that “hot spot” would also move.

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Posted: 08 August 2012 10:43 AM   [ Ignore ]   [ # 5 ]
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Occlusion with Soft Shadows Mode
Next, is the first “Occlusion Mode” or “Occlusion with Soft Shadows”. What is Occlusion? Well, without getting TOO technical, ambient occlusion determines which areas of geometry are bright and which are dark (occluded). It does this by bouncing light off the object and light that makes it back to the camera makes an object brighter. Light that doesn’t makes that part of the object darker.

Now, soft shadows… We know that there’s another Occlusion mode (Directional Shadows) so what does Soft Shadows mean? Well, effectively it means non-directional. This means that the Environment Map we’ve specified WILL NOT affect the ‘input’ of the light when calculating what is occluded.

So here’s what the same scene looks like with Occlusion w/Soft Shadows set as the Environment Mode.

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Posted: 08 August 2012 10:45 AM   [ Ignore ]   [ # 6 ]
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Total Rendering Time: 1 minutes 14.18 seconds

Now, once again, let’s look at the red sphere. The “Hot Spot” of illumination is still there. You can clearly see what direction the light “appears” to be coming from… Now look at the plane around each object. You have a fairly uniform shadow (occlusion) around / under everything. It looks pretty good, but given the obvious light direction, it doesn’t look very realistic does it?

Now, how and why would we use this mode? Well, much like Ambient Environment Mode, I can see this mode being useful with “helper lights”. In fact, I tend to use this mode (without an Environment map) in almost all my out door scenes. This gives a reasonable approximation of a more global lighting setup, leaves the directional shadows to fixed, traditional lighting and, well, provides occlusion globally instead of per surface but (without a map) you don’t have to worry about aligning the Environment map with the traditional light setup. Handy. Although, not terribly accurate as I’ve mentioned.


Occlusion with Directional Shadows
Next, is probably the most commonly used mode (since that’s how it loads by default) of UE2…

Occlusion with Directional Shadows. In this Environment Mode, the render engine takes the trouble to create a much more accurate light source (or light source with varying intensity perhaps would be a better way to think of it). This gives use “directional shadows” and “directional occlusion”.

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Posted: 08 August 2012 10:49 AM   [ Ignore ]   [ # 7 ]
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Total Rendering Time: 1 minutes 34.40 seconds

Now we can see that the occlusion matches what we would expect with the “hot spot” on the red sphere. Things look more like what we would expect in the “real world.”

This is the first mode of UE2 that I (personally) feel can be used without much in the way of traditional lighting assistance. However, I still tend to add additional lights to the scene I just take great care to ensure that I line the “sun” of the environment map up with the direction of my primary traditional light source.

This is also a good time to bring up the major shortcoming of UE2 in DS3. UE2 in Ambient Occlusion mode does not produce, and in fact, reduces every surfaces specular response. This tends to make things look muted, even though the brightness of the scene may be fine. The way to avoid this, in my experience, is to add a distant light at a low to moderate intensity with an Illumination Mode of “Specular Only” and align that light to match the primary direction of the Environment Map you’re using with UE2. This effectively “doubles up” on the specular area and can bring back that depth that UE2 tends to mute. Often it takes me a few stabs at finding the right strength, but I tend to start at 30-40% and go up from there. Rarely higher than 75% but it’s happened.


IDL with Soft Shadows
Next, we’ll try the first of the IDL modes. IDL or Indirect Lighting is basically the ultimate step that UE2 can take. It effectively, combines the Occlusion Modes with an “extra series” of light bounces (partially controled by Raytrace Depth on your advanced Render tab, but also controlled by the Maximum Trace Distance on the Parameters tab with UE2 selected).

This mode uncovers one of the biggest flaws with the basic Occlusion modes… Do you expect the soft shadows here to have the same issues they have in Occlusion Mode? You should, because they do… however, that’s not the issue. Let’s look.

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Posted: 08 August 2012 10:50 AM   [ Ignore ]   [ # 8 ]
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Total Rendering Time: 19 minutes 35.61 seconds

Now, isn’t that interesting? Can you spot the difference between this render and the Occlusion with Soft Shadows mode render? I’ll give you a hint, look at the red sphere. Yup, the “bounce” light has caused the red of the sphere to “reflect” onto the white of the plane. This mode much more closely resembles the way the “real world” works… However, the lack of direction kind of ruins it.

Still, I would use this mode pretty much the same way I would use Occlusion w/Soft Shadows.


IDL with Directional Shadows
Now, let’s look at the IDL w/Directional shadows mode…

This is it… This is the mode where it all comes together and things look fantastic. At least I think so. We still have the specular problem but now shadows makes sense, occlusion looks accurate, and the bounce gives us the color blending that our minds have come to expect…

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Posted: 08 August 2012 10:51 AM   [ Ignore ]   [ # 9 ]
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Total Rendering Time: 22 minutes 38.30 seconds

All of that came at a price though. The scene that took 7 and half seconds to render at Ambient Mode and just over a minute in Occlusion modes… took over 22 minutes to render in this mode. Keep in mind that there are no hefty transmaps, reflections or much in the way of “traditional” things that cause “render time increases” in this scene. Yikes. You definitely pay for that extra realism.

All in all though, I think this is a mode of UE2 I need to really explore as it seems to create the most realistic results we’ve seen thus far.


Bounce Light (GI) Mode

But wait, there’s still one more mode… “Bounce Light (GI)”. Do not confuse this with true Global Illumination. It isn’t. This mode is what is ADDED to the Occlusion Modes to generate the IDL Mode.

By itself this mode does not appear to be very useful at all. However, it looks like it will work nicely if you supplemented it with traditional lighting. This would give you the benefit of color bouncing without the added penalty of Occlusion. This would work well if you were using Surface based occlusion (i.e., UberSurface, Elite Human Surface Shader or pwSurface).

For the sake of completeness, here’s the same scene above, no additional changes made, other than the Mode using the Bounce Light mode. Note you can see the color bounce onto the area of the plane around the red sphere, but the shadows are terrible. I believe this is because there’s no “real” light source and if there was, the spottiness would go away.

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Posted: 08 August 2012 10:51 AM   [ Ignore ]   [ # 10 ]
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Here’s the kicker though… Total Rendering Time: 1 hours 3 minutes 13.46 seconds

Yikes. O_O I’m hoping that’s because it had to deal with the situation of not having a primary light to work with. Even the omnifreaker UE2 documentation states specifically that this “method is designed to be used to enhance traditional lighting scenes. When using this mode, spotlights, point lights, etc should be the main source of light.”

‘ll have to experiment with that some more.

I think that’s a good start to the journey. We’ve seen what little I know and we’ve seen what the various Environment Modes do.

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Posted: 08 August 2012 10:53 AM   [ Ignore ]   [ # 11 ]
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Journey 02: Map Controls

Alright, as I said at the end of the first lesson we’re going to talk about the Map Controls in this lesson. There are only two of different map controls (Saturation and Contrast), but it may or may not be clear what they do.

So we’re going to take the trial by fire method and see what happens. smile

I’ve created a new scene for this one, this time only using primitives and I loaded UE2, set high quality, set the environment mode to IDL w/Directional Shadows and click render. That’s where we’ll start…

This is the base image.
Map Controls -
Saturation: 100%
Contrast: 100%

I’ve added some arrows to each image to help demonstrate what I am observing in each setting.

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Posted: 08 August 2012 10:55 AM   [ Ignore ]   [ # 12 ]
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So we can see a pretty clear specular response on each item… the directional shadows, the occlusion near the ground plane as well as the color bounce we’d expect from IDL.

Nothing new here. For best results following the rest of this, full view the image above (click on it) and save it out to a folder somewhere. You’re going to want to save each image so you can cycle back and forth through them clearly.

Name this first image, something like “00a IDL Direct 100 Sat 100 Con.jpg”


Map Controls: Saturation

The next image, I’ve reduced the saturation to 50%. What this actually does is reduce the impact of the COLOR on the HDRI Map. Part of what this seems to do is make the specular response larger, but what I believe it actually does, is simply create less shadow.

Image : “00b IDL Direct 050 Sat 100 Con.jpg”

The next image, I’ve reduced the saturation to 50%. What this actually does is reduce the impact of the COLOR on the HDRI Map. Part of what this seems to do is make the specular response larger, but what I believe it actually does, is simply create less shadow.

Image : “00b IDL Direct 050 Sat 100 Con.jpg”

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Posted: 08 August 2012 10:55 AM   [ Ignore ]   [ # 13 ]
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And here’s Image : “00c IDL Direct 000 Sat 100 Con.jpg” where I’ve reduced the saturation to 0%.

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Posted: 08 August 2012 10:56 AM   [ Ignore ]   [ # 14 ]
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Cycle through those a few time in your favorite image browser… You can watch the effect pretty easily. What it’s really doing, as I mentioned before is affecting the saturation of the color in the HDRI map. This works pretty much like Image Saturation Control in your favorite image editing software. Reducing the saturation to 0% effectively makes it grey scale. This has a fairly big impact on how the rendering engine determines what is casting light and what isn’t and I believe is what causes the overall “decrease” in the intensity of the shadows (how dark they are) because more things are being considered as light sources.

So I think I understand what Saturation does, though the when and how of its application is still something I’m considering. I think, ultimately, that you’d probably choose to reduce the saturation if you found the results of your Environment Map to be too harsh. Lowering it would create a smoother more balanced image.

Map Controls: Contrast
So, given how Saturation works, what about Contrast? How will it work I wonder?

So again, we start off with a base image…

This time call it: “01a IDL Direct 100 Sat 100 Con.jpg”

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Posted: 08 August 2012 10:57 AM   [ Ignore ]   [ # 15 ]
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Now, here’s “01b IDL Direct 100 Sat 050 Con.jpg” which is at 50% contrast.

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