Digital Art Zone

Hi.  Alan here, of www.alanscape.com.  This is my gallery thread in the Art Studio section (obviously), but I figure it can also serve as a repository for the techie “playing around” that seems to occupy so much of my DAZ Studio time.  Hey, it’s all part of the fun of the hobby, right?

The first sequence of posts was on jury-rigging a Spot Render within DAZ Studio.

Next came tests of Sub-Surface Scattering.

Currently, I’m experimenting with an UberEnvironment 2 Lighting Rig.

How To Improvise a “Spot Render” in DAZ Studio . . . [Transferred from another thread.]

Shaaelia - 16 August 2012 08:57 PM

...  I wish I wish I wish that there was a way to save a spot render out at a particular resolution. ...

I can’t remember which thread it was in, but someone somewhere posted a clever trick for doing this in DAZ Studio.  Basically, it’s a variant on the old artist’s framing/composition aid that uses two L-shaped pieces of cardboard as an adjustable viewfinder.  (Maybe someone with a better memory and/or search fu can find the post.)

As an example, suppose I wanted to change just the hairstyle on this render…

Here’s a screencap showing the camera I’m reusing, with the “two Ls” gadget blocking out the parts I don’t want to re-render. I used two different pastel-ish colors here, for illustration purposes, but any color would work.

The surfaces of the L objects are using the standard “DAZ Studio Default” shader, with Diffuse strength at 0%, Specular strength at 0%, and Ambient strength at 100%. (It’s the kind of surface setup you’d use on a sky dome.) This leaves very little for the render engine to calculate, so the blocked-out areas render very quickly.  I also set the L objects not to cast shadows (again, like a sky dome) to pick up a little more speed.

For positioning convenience, I parented the two L objects to the camera.  I zeroed out their rotations—- except for rotating the second L in the Z plane by 180 degrees.  Then I translated them around until I had blocked off everything but the spot I wanted to re-render. They ended up quite close to the camera, as you can see.

Here’s the resulting “spot render.”

Since the changed area was near the top, I didn’t even have to let the render run to completion.  (Although I still wasn’t fast enough to stop it right after the important part was done!)  This is using the default “Bucket Order” of “Horizontal” (which is set in the Advanced options of the Render tab.)  If I needed to re-render an area near the lower left of the image, I’d use “Vertical,” which works its way across in vertical columns.  The “Spiral” bucket order works outward from the center.

For a spot render in the lower right corner—-  oh well, I guess I’d be waiting for the full render.  But not as long as I would be if I didn’t block out the rest of the scene…

[Reserved for composite.]

The L object that I used is tiny, so here’s a code embed:

Cut-&-paste the above into a plain text editor, save it as an .obj file, and import that into DS at Hexagon scale.

Sub-Surface Scattering

After a few months of occasional attempts at using Sub-Surface Scattering, I finally got around to setting up a simplified experimental rig, to try to isolate what some of the different settings actually do.

First off, credit goes to RawArt for providing some good starting settings. It sure helps to have some kind of effect visible before you start spinning dials at random… 8^j*  I also snagged a copy of Dimension Theory’s Interjection product during last month’s PA sale, which saved me the truckload of hours it would have taken to construct my own SSS maps for the 4th gen figures—- and provided another set of UberSurface settings to experiment with.

Attached are a sample render of “Four Levitating Bowls and a Bald Vicki,” plus the goofy SSS test map I used for the surfaces on the bowls. (If you want to use the latter for your own experiments, click through to get the original version without the extra level of JPEGgery introduced by the forum previewer code.)  All four bowls use the same starting UberSurface settings, with different sections shut off.

The bottom bowl has no Ambient and no SSS active.  The Diffuse is at 100%—- more on that in a bit.

The left bowl (viewer’s left) has Ambient on but still no SSS, with Diffuse at 95%.

The right bowl has SSS on, no Ambient, and Diffuse at 95%.

Finally, the top bowl (viewer’s left) has Ambient on, SSS on, and Diffuse at 95%.

Next up, dissecting the settings…

On the “test bowls,” I left most of the UberSurface settings at their defaults—- in the attached composited screencap, a bunch of the subheadings have been collapsed.  Those values are as the base UberSurface load initialized them.  Proceeding from the top,,,

The Diffuse color is a jpeg, medium beige, with a little multi-color Gaussian noise added, and multiplied by a peachy [255,238,221] off-white.  It’s a nice utility skintone for when I want to isolate the effects of settings—- the painted-in details in a good skin texture make those harder to pick out.  Why 95% strength?  Because in early experiments, highlights were getting “blown out” (i.e., kinda over-exposed looking) when I added in Ambient and SSS.  Depending on the skintone/lighting/glossiness you’re using, that dialing back may not be necessary.

There’s just a smidgen of texture in the Bump channel: a little Gaussian noise again.

Went a little bit shiny with the Specular, for a slight ceramic effect on the bowls.  On skin, the UberSurface defaults are pretty plausible, but this is something you’d adjust according to the needs of the image.

This is a fairly bright & saturated Ambient color, but it’s dialed way down to 4.2%.  It’s also applied only in the areas designated by my SSS map.  Again, you have a lot of creative leeway here, depending on the skintone and desired effect.

Velvet is used here to emulate looking through a semi-transparent ceramic glaze layer near the edges of the object, where the surfaces are almost turned away from the viewer.  So you’d be looking through it at a shallower and shallower angle as you approach the edge, and therefore a thicker and thicker amount of the glaze.  It’s a similar idea with the fine hairs on human skin.  Lots of leeway for experimentation here.

And finally, the main event: Subsurface Scattering.

For its color, I used that medium beige jpeg again, this time multiplied by a traditional pink—- that “subcutaneous blood” tinge that skin SSS is meant to emulate.  Went pretty high with the Strength here, racking it up to 75%.  And it’s applied where my SSS map specifies, naturally.

Searching around, I found refractive index numbers for skin (and water, responsible for a large part of skin’s optical properties) quoted ranging from 1.3 to 1.5, depending on bunch of factors—- notably, the wavelength of light involved.  I chose a kinda middle of the road value; for skin, the 1.3 to 1.5 range of settings doesn’t seem to cause wild changes in the final effect.

The Scale setting, however, was a surprise.  I’ve read various descriptions of it as determining how far the light penetrates the object—- which is true enough, I suppose.  But I find it more useful to think of it as affecting how much blur is in the final SSS effect, as seen in the actual render.  For a larger object, such as a giant creature or humanoid, you’d use a larger Scale value to soften the edges, to be “in scale” (nyuk nyuk) with that larger being.  And you’d go smaller for smaller figures, naturally.  The ratio is nicely linear, fortunately.

(When I first started my SSS experiments, I had the Scale value way too high, which caused the SSS effect to blur into imperceptibility.  Sheesh!)

Group?  I have no idea yet what this is actually used for.  I set it to a plausible integer and then ignore it. 8^j*
[Update!]  There’s a thread explaining this very slider.  Short version: you put surfaces in a group to have them calculated together as a unit, AND to avoid them getting interference from a different group.  For example, group all the skin zones as one group, and group all the mouth surfaces in a different group—- and maybe, just maybe, avoid what Rawn calls “Lava Mouth.” More experimentation on this to follow.

Shading Rate is a quality setting.  Unlike the Uber lights, higher values mean lower quality, less computation load, and faster renders.  On this relatively simple image, the delta between rendering at 128 and rendering at 16 was only about a 2% increase in render time.  Pushing to 4 took 11.5% longer than the render at 128.  Visually, the higher quality translates to a smaller blur and more intensity in the SSS effect.  The default of 32 is probably a good tradeoff point; I couldn’t see a significant difference between the the renders at 16 and 4.

The eagerly sought-after Ear Glow !

Note that this is SSS alone, without any boost from Ambient.  For my purposes, I rather prefer this approach.

Here’s a look at the test bowls from the shady side, while Vicki takes a break. Topmost is SSS+Ambient; leftward, SSS alone; rightward, Ambient alone; bottom, none of the above.

Note how the SSS by itself responds to the availability of light.  Where that bowl’s curvature causes a contour shadow on the outside, the glowy fuzzy SSS pattern on the inside fades out.  The same occurs within the shadow cast by the top bowl.

Ambient effects, on the other hand (bowl), glow regardless of whether light is hitting the surface or not.  Also, they don’t look very “scattered.”

Overall, if I’m faking an effect of scattered light, I’d prefer that the method pay attention to how much light is available.  When the lighting of a scene is bright and sunny with loads of ambient light from all directions, the Ambient substitute will do, provided the SSS map is already fuzzy.  When the lighting is more chiaroscuro, it looks like I’ll be tuning the SSS effect to be sure it’s perceptible.

Still have to figure out how to produce an exaggerated waxwork effect within DS, though…

alanscape - 07 October 2012 08:45 AM

Group?  I have no idea yet what this is actually used for.  I set it to a plausible integer and then ignore it. 8^j*
[Update!]  There’s a thread explaining this very slider.  Short version: you put surfaces in a group to have them calculated together as a unit, AND to avoid them getting interference from a different group.  For example, group all the skin zones as one group, and group all the mouth surfaces in a different group—- and maybe, just maybe, avoid what Rawn calls “Lava Mouth.” More experimentation on this to follow.

Sorry to interrupt, and I hope this is helpful.

With Ubersurface2 and Daz Studio, at least, you can avoid or at least sharply decrease “lava mouth” by turning the Translucency strength on the mouth textures down—teeth, gums, tongue, and whatever the other one I can’t remember right now is (I don’t have Studio on this workstation at the moment).

“Lava Mouth” is largely caused by translucency making light glow through the skin, as far as I can tell. Turning Translucency down doesn’t necessarily seem to work as well with Interjection; there’s something very different about the way the two shaders seem to work—I think in part because Interjection actually uses Ambient for part of its effect, and Ubersurface2 defaults to doing whatever the mat settings are telling it to do. Even when you allow Ubersurface2 to replace mat settings instead of ignoring them, it doesn’t generally turn Ambient on, at least not in the settings I’ve tried on human textures.You don’t need to touch the external textures for the head to get rid of the effect, and you don’t necessarily need to assign the textures to a separate group. (No, it does not make logical sense that turning down translucency on textures that aren’t structurally external—and therefore the ones that translucency should be affecting the least—works, but it does. Logically, if the external head structure isn’t translucent, but the internal mouth structure is, you wouldn’t see anything until the character opened their mouth. This is not the way Studio works. No idea why.)

(Honestly, since you can—and, actually, must—work with textures separately within the same group, I don’t quite understand what the Group setting is doing there. Even when you assign given textures to a specific group, you still need to deal with each texture separately. I’ve read the thread you linked, but I think I’m just missing something about how Group works.)

Thank you for going through all this; it’s been really informative about how the shaders work and why.

An “interruption”?  On the contrary—- I’m gratified (and a little relieved) to hear that someone else is reading this thread.   Although it’s a valid way to make notes for my own future reference, I suppose.  Still, one has hopes, y’know…

Regarding grouping versus having to deal with textures/zones separately: As I read that thread, I don’t think the Subsurface Group stuff is for helping me, as an end user, to manipulate a bunch of material zones as a unit. I think it’s just a directive for the shader code, telling it to calculate some areas together, and some separately.  ReDave’s point about “no boundary between different material zones that belong to the same group” is a key concept, I believe.

To test this idea, I’d set up two adjacent material zones in an object with the same general SSS settings, and place a bright area of SSS map in one of the zones, right next to the boundary.

- If I assign both material zones to the same Subsurface Group, the SSS fuzzy glow should “bleed” across the boundary.
- If I assign each zone to its own unique Subsurface Group, the SSS fuzzy glow should stop at the border.

I’ll go try this and post the results.

On the glowy mouth syndrome: I vaguely recall stumbling into this in early efforts, but I didn’t pay much attention—- I think I just set the mouthparts’ shaders back to “DAZ Studio Default” and carried on with whatever was occupying my interest at the time.  If I can recreate this condition intentionally, I’ll try your suggestion.  Thanks!

cheers
Alan

Yep, that’s how it works.

The bauble farther away from camera has both material zones assigned to the same Subsurface Group, while each material in the nearer bauble is assigned to its own separate Subsurface Group.

I also varied the Diffuse color slightly, to make the boundary more distinguishable, and tweaked the (Basic Primary) Specular settings to taste.  Apart from those and the SSS settings, everything else is at UberSurface default values—- mostly “Off,” notably including Translucency and Ambient.

alanscape - 10 October 2012 10:31 AM

Yep, that’s how it works.

The bauble farther away from camera has both material zones assigned to the same Subsurface Group, while each material in the nearer bauble is assigned to its own separate Subsurface Group.

I also varied the Diffuse color slightly, to make the boundary more distinguishable, and tweaked the (Basic Primary) Specular settings to taste.  Apart from those and the SSS settings, everything else is at UberSurface default values—- mostly “Off,” notably including Translucency and Ambient.

Ah, OK. so probably not something you’d use much on a human texture unless you were trying to do something like a tan line; you could assign SkinHip to its own group and get that old-school Coppertone commercial look while keeping somewhat the same settings as the surrounding textures. It’s nice to see how that works in practice.

alanscape - 10 October 2012 05:22 AM

On the glowy mouth syndrome: I vaguely recall stumbling into this in early efforts, but I didn’t pay much attention—- I think I just set the mouthparts’ shaders back to “DAZ Studio Default” and carried on with whatever was occupying my interest at the time.  If I can recreate this condition intentionally, I’ll try your suggestion.  Thanks!

If you start using Interjection at its default strengths, you’ll see it. In that case, however, it’s largely but not entirely due to ambient settings, so turning down translucency doesn’t work. Ambient seems to be part of what needs tweaking to get that waxy look you mentioned, by the by.

I don’t tend to see lava mouth with EHSS/Ubersurface2, but that’s also in part because when I use Ubersurface on human characters, I turn down translucency on mouth textures so that it’s never above 10%, and usually in the 6-8% range. That may be overcompensating, but the first time I ran into the issue, it took forever to figure things out.

vwrangler - 10 October 2012 11:25 AM

Ah, OK. so probably not something you’d use much on a human texture unless you were trying to do something like a tan line; you could assign SkinHip to its own group and get that old-school Coppertone commercial look while keeping somewhat the same settings as the surrounding textures. It’s nice to see how that works in practice.

Or the “second skin” clothing technique, now somewhat fallen out of use—- see attached. 8^D*  In this case, the DAZ Studio Default shader sufficed for Vicki’s “bicycle shorts,” but now I have the option of using one of the UberSurface family of shaders.

By the way, those hours in Photoshop that I avoided by purchasing Interjection?  Spent ‘em making simple skinhip displacement maps for the 3rd and 4th generation figures… 8^j*

vwrangler - 10 October 2012 11:25 AM

If you start using Interjection at its default strengths, you’ll see it. In that case, however, it’s largely but not entirely due to ambient settings, so turning down translucency doesn’t work. Ambient seems to be part of what needs tweaking to get that waxy look you mentioned, by the by.

Noted, thanks.  I suspect the weird glow thing may also show up more clearly in different lighting than the overcast-ish setup I’ve used in this series.  (One muted UberEnvironment2 light providing ambient & occlusion effects, plus one soft distant light.)

vwrangler - 10 October 2012 11:25 AM

I don’t tend to see lava mouth with EHSS/Ubersurface2, but that’s also in part because when I use Ubersurface on human characters, I turn down translucency on mouth textures so that it’s never above 10%, and usually in the 6-8% range. That may be overcompensating, but the first time I ran into the issue, it took forever to figure things out.

Thanks!  That tip has already saved me a bunch of hours: translucency certainly wouldn’t have been the first suspect I’d have looked at…

Thank you so much for the comment, Alan

Will reply in greater depth in my own thread but wanted to let you know I started reading this and thank you so much for sharing this information