Considering Material Details

This Render Passes article is not about the details of the Poser Materials, but it is worthwhile contemplating them a bit. As you have noticed in previous chapters, aspects like Diffuse, Specular and Shadow can be diverted to separate layers or images. This gives me the possibility to handle color, highlights and darks in details, even on a per-light basis.

But Poser supports other aspects, like Ambient and Reflection, and also supports Indirect Lighting (IDL). How do these relate to the split (in Poser) and glue (in Photoshop) approach? And what are then the best ways to get the required results out efficiently?

My suggestion on doing Render Passes, which applies to all cases that PoserPro is used, is to switch off Gamma Correction. Because:

• Rebalancing highlights and lowlights can be done in post, based on the available layers
• When required the fine details in shadows can be secured by making a Shadows Only render, and then using Gamma Correction or – even better – exporting that result in high definition (EXR) format. But since the nuances in the dark usually appear in situations with dark colors combined with shadows, and render passes present those separately and make you the chief of the combination, it becomes questionable whether separate techniques are required to get those details in the individual layers themselves.

Just FireFly

When using just Firefly I can make a shadows-only and a shadow-less result as described in chapter 2 Separating the Darks. Unless I’ve got Poser Pro 2010+, I can select sub-passes in the Auxiliary Render Data list in Render Settings, as described in chapter 4 Featuring Poser Pro.

• Custom 1
  presents Diffuse, Ambient, Refraction and – given the chance – Shadows. And in the case of IDL: plus color bleeding and all consequences of using too much light (like loss of shape and depth), especially when a SkyDome is introduced as an additional omnipresent light source. All in one result. Too loose the shadows I’ve got to uncheck Cast Shadows.
• Custom 2
  presents Specular and Reflection, both in one result. Whether or not Cast Shadows is checked does not matter.
• Custom 3
  presents Shadows, if Cast Shadows is checked, otherwise it’s blanc. In the case of IDL, shadows will get reduced by the surplus of available light, which becomes especially noticeable with a SkyDome around the scene.

The other sub-passes behave as described earlier. So, I just make a run with Cast Shadows checked without Custom 1 elected, and another run with Cast Shadows unchecked, with only Custom 1 selected. And I do have to save to an 8-bit per color format (PNG) as those sub-passes don’t apply to the high definition (HDR/EXR) formats.

The Render Pass Script

As described in chapter 3 Separating the Lights, this script generates separate passes per direct light in the scene. And then, when Poser Pro is used, is also saves these light-passes with the sub-passes described above. Then the case of using IDL and SkyDomes becomes interesting: at each light-pass, the SkyDome lighting is present too, but somewhat reduced compared to the final, total render. I don’t know how they do it, but when the Light-passes are combined in Photoshop using Screen blending mode, the IDL lighting appears properly. I imagined there could be a problem, having IDL present in each Light layer, but there isn’t.

The script also offers Occlusion and Ambient. Both come as rendered with all lights off. Without IDL, the Ambient pass presents a combination of Diffuse and Ambient but I don’t know what to do with it, while the Occlusion – Custom 1 pass offers the Ambient alone and the Custom 3 pass offers the neat self-shadowing. With IDL however, the Ambient pass presents a neat ambient while Occlusion still presents the self-shadowing, but goes wild in the Custom 1 sub-pass. That is: since all direct lights are off, a SkyDome with its color in Diffuse will not contribute either and leaves the Ambient channel of the ball, plus some color bleeding. But when the color of the Dome is in Ambient, the Occlusion- Custom 1 subpass presents us some IDL-only like version of the scene.

Are you still with me? Or are you feeling a bit like: let’s shut on and off IDL, let’s shut on and off shadow catching, let’s switch on all auxiliary sub passes, let’s render, and then let’s pick everything that might contribute to the result. Can’t blame you, sometimes that my approach too.

So, where are we?

• I can get Occlusion (self shadow) separately.
  I just use the RenderPass script and check Occlusion.
• I can get Shadows, separately, even per light.
  Either by rendering with Shadows Only or by selecting the Custom 3 sub-pass (PoserPro, 8-bit per color output (PNG, not EXR), and preferably IDL off), and by using the RenderPass script for a per-light result.
• I can get Reflection and Specular, but only together. And per light separately
  That is: by selecting the Custom 2 sub-pass which requires PoserPro, 8-bit per color output (PNG). IDL does not matter, and I can use the RenderPass script for a per-light result.
  Not bad, as both are different sides of the same medal: reflection deals with surrounding objects while specular deals with the direct lights. In real life, these always come as one. The downside is that I have to find the right balance in Poser itself. But as long as raytrace nodes are used instead of reflection maps, I might render with raytracing switched off to get Specular only. And I can render while having all specular channels of the lights switched off, manually (or with a script). This might give me Reflection only, but without the reflection of the specularity in the surrounding objects.
  Does it matter whether I use reflection by raytracing or use a reflection (texture) map instead? No.
• I can get Ambient, separately
  I just use the RenderPass script, check Ambient and set IDL on. Or I leave IDL off, check Occlusion and use the Custom 1 subpass which requires PoserPro and 8-bit per color output (PNG).
• I can get Diffuse but only in combination with Ambient and Refraction.
  It requires the Custom 1 subpass which by itself requires PoserPro and 8-bit per color output (PNG), and preferably set Cast Shadows OFF. When using the RenderPass script it comes even per light. When the final result requires IDL, leave it on here as well but do note that a strong IDL SkyDome may wash out most object-shape and scene-depth.

Advanced Render Settings 2

Do I need an additional tool, as most of the passes can be made without it? I think I do, since it not only can do more and better but also saves me most of the hassle.

In the first place I can get Z-depth and Altitude (the Y-part of Position) and Alpha MAT (the equivalent of Toon/Object ID) without the sub-passes, and hence without the need for PoserPro or with PoserPro, it works for the high definition output as well.

Second, I can get Shadows, and everything else shadow-less, in one go: I just check the Shadows option and I uncheck the Cast Shadows for rendering, as the shadow pass is generated even when they’re off in the rendered result (tip: save the settings before rendering). I can ask for separate light-passes as well (even separate figure passes). I must render without IDL though, hence I can get it without the need for PoserPro or with PoserPro, it works for the high definition output as well. Note that I can get separate shadows in an IDL render as well, but that requires the Custom 3 subpass, and why should I follow the hard way?

Third, I can separate Reflection and Specular, provided that I render without IDL and that I use the Custom 2 pass. So that requires PoserPro and 8-bit per color. The reflection then can be found in the Color \ Custom 2 pass.
Specular comes on a per-light basis, when requested so by ticking that option. Note that if I don’t crank out the reflection as described, I can still get the Specular + Reflection combination in the Custom 2 sub-passes of each light. I can’t get Reflection out separately when using just Poser, or when exporting to EXR.

Forth, I can get Diffuse and Ambient out separately, I just tick the boxes. Diffuse can come per light, as requested. In the meantime, the (per light) Custom 1 sub-passes give me Diffuse + Ambient + Refraction, and those sub-passes require PoserPro and 8-bit per color (PNG) output. I’ve found no way yet to get out the Refraction separately. But at least I can alter the effect by adding or subtracting Ambient and/or Diffuse from this layer, which is nice anyway.