Category: Poser

The captured image itself is determined by the camera Field of View, the Poser backend does not auto-adjust to lighting variations; it offers a fixed sensitivity. A 100% diffuse white light plainly lighting a 100% diffuse white object will create a 100% white lit area in the result. Adding more lights, and/or adding specular lighting on top of this will make the image overlit: higher lighting levels get clipped and details will get lost.

Given image contents, the Poser Renderer has an adjustable resolution: I can set about any image size in pixels, maintaining the Field of View. Poser Pro also supports 16-bit-per color (HDR, EXR) image output to ease enhancements of low lighting levels in post, and also supports various forms of render passes: splitting the result into separate images for separate aspects of the image, to ease advanced forms of post-processing (see my separate Poser Render Passes tutorial). A real-life camera can’t do all that.

Rendering takes time and resources, a lot. Rendering techniques therefor concentrate on the issue: how to get the most out of it at the least costs. As in most cases, you and me, the users themselves, and our processes (workflows) are the most determining factor. Image size, and limits on render time come second. Third, I’ll have to master the settings and parameters of the renderer. And last but not least I can consider alternatives for the Poser Firefly renderer.

Render habits

In the early days, computers were a scarce resource. Therefore, programmers were allowed to make three tests maximum before their compiled result proved flawless, and could be taken into production. At present, computing power is plenty, and some designers press the Render button about every 5 minutes to enjoy their small progress at the highest available quality. For 3D rendering, any best practice is somewhere in the middle.

Rendering takes time and resources, a lot. But modeling, texturing, and posing (staging, framing, animating) do take a lot of time as well. Therefore it makes sense to put up some plan, before starting any project of some size. Not only for pros on a deadline, having to serve an impatient client. But for amateurs or hobbyists like me as well or even more so, since we don’t have a surplus of spare time and don’t like to be tied to the same creative goals for months.

First, especially in animating, I concentrate on timing, framing (camera Point of View) and silhouettes. In stills, my first step should be on framing, basic shapes, and lighting – or: brightness levels and shadowing. Second, colors (material hues) and some “rough details” (expressions) kick in. Third, material details (shine, reflection, metallic, glass, stains, …), muscle tones, cloth folds (bump, displacement) enter the scene. And finally, increasing render quality and similar advanced steps become worthwhile, but not before all steps mentioned above are taken up to a satisfying intermediate result.

In the meanwhile, it pays off to evaluate each intermediate render as completely as possible and relevant, and to implement all my findings in the next round. I just try to squeeze a lot of improvement points between two successive renders, instead of hitting the Render button for celebrating each improvement implemented. Because that’s so much a waste of time, it’s so much slowing down the progress in my work.

So, while I am allowed more than three test runs for my result, I use them wisely. They do come at some cost.

Render process

So the one final step in 3D imaging is the rendering process, producing an image from the scene I worked on shaping and posing objects, texturing surfaces and lighting the stage. This process tries hard to mimic processes from nature, where light rays (or photons) fly around, bounce up and down till they hit the back plane of the camera, or the retina of my eye. But in nature all zillions of rays can travel by themselves, in parallel, without additional computation. They’re all captured in parallel by my eye, and processed in parallel by my brain.

A renderer however is limited in threads that can be handled in parallel, and in processing power and memory that can be thrown at them. Improved algorithms might help to reduce the load and modern hardware technology might help to speed up handling it, but in the end anything I do falls short compared with nature.

This issue can be handled in two ways:

• * By reducing my quality requirements. Instead of the continuous stream of light which passes my pupils, I only produce 24 frames a second when making a movie. When making a single frame or image, I only produce a limited amount of pixels. Quality means: fit for purpose. Overshooting the requirements does not produce more quality, it’s just wasting time and resources.
• * By throwing more time and more power to it. Multi-threaded PC’s, supercomputers, utilizing graphics processors in the video card, building render farms over the Internet or just putting 500 workstations in parallel in a warehouse are one side of the coin. Just taking a day or so per frame is the other side. This holds for amateurs like me, who are happy to wait two days for the final poster-size render of a massive Vue landscape. It also holds for the pro studios who put one workstation at the job of rendering one frame over 20 hours, spend 4 hours on backup and systems handling, and so spits out one frame a day exactly – per machine. With 500 machines in sync, it takes them 260 days to produce a full featured 90 minute CGI animation.

Instead, I’ll pick up the first way, and turn it into

How to reduce quality a little bit while reducing duration and resources a lot.

Of course, it’s entirely up to you to set a minimum level for the required quality, in every specific case, I can’t go there. But I can offer some insights that might be of help to get there effectively and efficiently.

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Since mankind started cinematography, it was well understood that the human eye could not discriminate individual images when they passed by at a rate over say 18 a second. So by setting a 24 frame per second rate on film (or 25 (PAL) / 30 (NTSC) for video/television) a reduction of resources was derived without any meaningful loss of quality – referring to the visual experience of the spectators.

Next to chopping a continuous stream of light over time, we can chop it over space and divide an image into pixels. Again, this can be done without any meaningful loss of quality if we take the limitations of our eyes into consideration.

Very good and very healthy eyes have a discriminating ability of about 1 bow-second. One can’t do better than that. One full circle makes 360 degrees, 1/60^th of a degree makes a bow-minute and 1/60^th of a bow-minute makes a bow-second. When I’m looking forward in a relaxed way, I can oversee about 70° really well while say 150% of that (105°) is covering the entire range from left to right. This 70° makes 70*60*60 = 252.000 bow seconds (378.000 for the 105° field), so it does not make sense to produce anything over that amount of pixels which has to be viewed from the left to the right of our visual range.

Unfortunately, this is hardly a relief as I do not intend to render images with a width or height in that amount of pixels. Fortunately, our eyes and brain become of help. In the first place, we don’t all have “very good and very healthy” eyes, they just aged over time like we did ourselves. In the second place, the extremes occur with our pupils wide open which is not the case when viewing images under normal lighting conditions. In cinema and before a monitor (television) it’s even worse: the image is radiating light in a darker surrounding closing our pupils even further.

As a result, a standard used commonly in research on visual quality takes the 1 bow-minute (and not the second) as a defendable standard for looking at images on TV or in cinema. Then, the relaxed view range of 70° requires just 70*60 = 4200 pixels while the full range (for surround and IMAX, say) requires 150% of that, a 6300 pixels wide image.

This can be compared with analog film. IMAX is shot in 70mm (2.74”) film size and a film scan can produce about 3000 pixels/inch before hitting the film grain limits, so IMAX can be sampled to at most 2.74 x 3000 = 8220 pixels and fills our visual range completely. In other words, for a normal relaxed view 4.000 x 3.000 does the job, while say 6.000 x 3.000 does the job in the full left to right range, for anything monitor, TV or cinema.

This is reflected in current standards for pro cameras:

For print, things are not that different. An opened high quality art magazine with a size of 16”x 11” (2 pages A4) printed at 300 dpi requires an 4800 x 3300 pixel image, which brings us in the same range as the normal and full view on monitor, considering our eyes as the limiting factor.

Of course one can argue that a print on A0 poster format (44”x 32”) might require 13.200×9600 pixels for the same quality but that takes people looking at it from the same 8” distance they use to read the mag. From that distance, they can never see the poster as a whole. Hence the question is: what quality do they want, what quality do you want, what quality does your client want?

I can also reverse the call: in order to view the poster in a full, relaxed way like we view an opened magazine, this A0 poster which is 2.75 times as long and wide should be viewed from a 2.75 times larger distance, hence from 22” away. In this case, a printing resolution of 300/2.75 (say: =100 dpi) will do perfectly.

Thus far, I’ve considered our eyes as the limiting factor. Of course, they are the ultimate receptors and there is no need to do any better, so this presented an upper limit.

On top of that, I can consider additional information about the presentation of our results. For instance, I might know beforehand that the images are never going to be printed at any larger format than A4, which halves the required image size (in pixels, compared to the magazine centerfold) to 3300×2400 without reducing its visual quality.

I also might know beforehand that the images are never going to be viewed on TV sets or monitors with a display larger than say 2000×1000 (wide view), which reduces the required image size to 1/3^rd in width and 1/3^rd in height, hence 1/9^th in the amount of pixels to be rendered, compared to the full wide view of 6000×3000 mentioned above for anything monitor or cinema.  Which might bring me the required quality in just 1/9^th of the time as well, but … at a reduced visual quality. The resolution of our eyes is just better than the output device, and I might want to compensate for that.

Quality Reduction Strategies

Render size

The main road to get quality results efficiently is: not to render in larger size than needed. An image twice as large, meaning twice as wide and twice as high takes four times longer to render, or even more if other resources (like memory) become a new bottleneck during the process.

Render time

As said in the beginning of this chapter, not much more can be done when the renderer depends on algorithm, hardware and image size alone. This for instance is the case with the so-called “unbiased” renderers like LuxRender, which mimic the natural behavior of light in a scene as much as possible. More and faster CPU cores, and more and faster GPU cores sometimes as well will speed up the result, but that’s just it.

Let me take the watch-scene (luxtime.lxs demo file) on my machine, at 800×600 size. The generic quality measure (say Q) is calculated by multiplying the S/p number (samples per pixel, gradually increasing over time) by the (more or less constant) Efficiency percentage which refers to the amount of lighting available.

• * Draft quality, Q=500, after 4 mins. Gives a nice impression of things to come, still noisy overall.
• * Basic quality, Q=1000, after 8 mins. Well-lit areas look good already, shadows and reflections are still quite noisy
• * Decent quality, Q=1500 after 12 mins, well lit areas are fine now
• * Good quality, Q=2000 after 16 mins, shadows are noisy but the reflections of them look nice already
• * Very good quality, Q=3000 after 24 mins, good details in shadow but still a bit noisy, like a medium res digital camera, shadow in reflections looks fine now
• * Sublime quality, Q=4000 after 32 mins, all looks fine, hires DSLR camera quality (at 800x600m that is).

From the rendering statistics, render times at least can be roughly predicted for larger render results. LuxRender reports for the watch-scene, given my machine and the selected (bidirectional) algorithm, a lighting efficiency E of 1100% and a speed X of 85 kSamples/second. These parameters can be derived quickly, from the statistics of a small sized render (200×150 will do actually, but I used 800×600 instead).

From the formula

 Q = 1000 X*E*T / W*H, for image Width and Height after time T,

 I get

 4000 = 1000 * 85 * 11,00 * T / 800*600 so T = 2053 sec = 34min 12sec

And from that I can infer that a 4000×3000 result, 5 times wider and 5 times higher, will take 5*5=25 times as long, that’s: half a day, as long as memory handling does not hog up the speed. Furthermore, quality just depends on lighting. Lighting levels too low or overly unbalanced cause noise, like on analog films or digital captures. Removing noise requires more rendering time. Specular levels too high (unnatural) cause ‘fireflies’ which don’t go away while rendering longer. I just have to set my lighting properly. And test for it in small sized brief test runs.

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Some render engines, called Unbiased or Physics based, mimic the behavior of light and real materials for obtaining their results. There is not much room for tricks or compromises, such engines require loads of resources, heavy machinery and might be slow as well. Other render engines, called Biased, come with bags full of tricks to shortcut the resource requirements while getting reasonable results fast. Poser and Vue offer such biased renderers. Of course they offer maximum quality settings which come as close to the unbiased ones as possible. But it seriously pays off to understand the enormous benefits of a somewhat reduced quality, and a slight deviation from the reality of nature.

So let’s start to discuss the options for the Poser Firefly renderer.

Shadow handling

Individual lights can be set to warp shadows, individual objects can be set to cast shadows, but the Cast Shadows option can switch them all off. Or: only when it’s ON, all individual settings are taken into account. By switching OFF, a completely shadowless render result can be produced. This makes sense when the action is combined with a Shadows Only render. This combined action results in two images which can be merged in post, and enables me to set the shadow intensity afterwards. It’s the first step in rendering with passes, as discussed in a separate tutorial on this subject.

A shadowless render also makes sense when calculating shadows takes a lot of time (eg when the scene contains loads of lights), while the shadows are not the issue yet in that specific stage of the project. Then switching OFF Cast Shadows is a time saver.

Polygon handling

Individual objects can be set to smooth, but the Smooth Polygons option can switch them all off. Or: only when it’s ON, all individual settings are taken into account. Switching OFF is a time saver at the cost of neat object shapes, which might make sense when precise object shapes are not the issue yet in that specific stage of the project.

Since the Poser renderer is clever enough not to take polys into account that do not contribute to the result anyway, the Remove Backfacing Polys option sounds like a manual override, which it is. Because it also disables the polys which are not facing the camera, but do contribute to the result in other ways. These might play a role in reflection (be visible in a mirror), refraction, indirect light emission, object shape and shadow via displacement, to name a few. Generally checking this option will cause a serious drop in quality while hardly saving rendering time, let alone exceptional scenes rendering on legacy hardware. So this might make sense when temporarily testing your main reflections and the like.

Displacement handling

Objects might use displacement mapping in their materials, but this only takes place when the Use Displacement Maps render option is checked. It details (subdivides) the object mesh and can increase memory requirements enormously. Displacement mapping is a good way of adding detail to objects at intermediate distances from the camera. Objects closer to the camera should have the details modeled in, objects further away can do with bump-mapping alone or – even farther away – without any mapping of this kind.

Displacement mapping might give the renderer some issues to handle, see the Divide & Conquer paragraph below.

Focal and motion blur

Motion Blur takes the shutter Start and Stop settings of the camera into account, and also introduces an extra step in rendering which takes additional time. Leaving it OFF puts the entire scene in a temporary freeze, suggesting infinite camera speeds or figures that can hold their breath and position for a split second, which by the way might be quite accurate for many situations. Also, switching it ON when the scene contains no animation at all only puts a burden on the rendering process without contributing to the result. On the other hand, do note that outdoor still shots with no blur at all on the tree leaves, grasses and animals around make quite an unnatural impression as well.

Scattering and Raytracing

A relatively new node in materials is the Subsurface Skin node, which adds some translucency effects to a surface as is present in muddy waters, human skin and waxy candles. It requires an extra render preparation pass, which is performed when a) such material nodes are present in the scene and b) the Subsurface Scattering option is checked. So, unchecking the option is meant for speeding up draft renders of scenes with scattering-intensive surfaces.

Raytracing addresses reflection and refraction of the actual surrounding objects by a surface, each pass or reflection of/onto a surface is called a “bounce”. Raytracing does not handle direct lights, does not handle scattering and does not handle reflection maps, but requires explicit reflection and refraction nodes in the material. When the Raytrace option is switched OFF those nodes are ignored, which is meant for speeding up draft renders of scenes with raytracing-intensive surfaces.

Note: using lights with raytraced shadows, and Indirect Lighting techniques also require Raytracing to be switched ON in Render Settings.

For final renders, the highest value is the best. It comes closest to nature’s behavior. It’s an upper limit for cut-off, so when no ray makes more than 3 bounces anyway, raising the value from 6 to 12 won’t make difference at all. You’re not forcing Poser into unnecessary raytracing, you’re just reducing artifacts, if any.

Indirect lighting

Caching

Irradiance caching is a technique which speeds up the calculations for Indirect Lighting (IDL) as well as self shadowing, or Ambient Occlusion (AO). A low setting implies a low number of samples taken from the scene (it’s a percentage, 0-100%). The colors, shadows and lighting levels for intermediate points are interpolated from them. This is faster, and less accurate. A high setting implies a more accurate result, at quite longer calculation times. For very high settings it might be better to turn off the mechanism completely to avoid the additional overhead of saving intermediate points and interpolating: just uncheck the option at all.

What are good values then? Well, have a look at the Auto-settings: values below 60 are not even suggested, which means Poser samples about every other point (just over 50%) for an initial draft result. Final renders take values up to 100, while any value over 95 could be better replaced by switching off the caching at all. Nature does not cache irradiance, so why should we?

During the IDL pre-pass, red dots in the scene reveal the Irradiance caching.

Lighting

Indirect lighting (IDL) turns objects into light sources. Either because they bounce direct (and other indirect) light back into the scene, changing its color and intensity. Or because they emit light themselves, due to very high settings (> 1) of their Ambient material channel. The method mimics natural lighting methods at their best, but requires an additional – time and resource consuming – rendering pass. Unchecking the option speeds up draft renders, but you lose the lighting as a consequence.

Indirect Lighting requires raytracing to be switched on, and the Bounces setting is taken into account as well. A low Bounces setting make the light rays die quickly, resulting in lower lighting levels, especially in indoor scenes lit from the outside. Here again, the highest setting is the most natural but will lengthen rendering time. Also, Irradiance caching is taken into account: lower values render faster but use interpolated results instead of accurate ones.

Irradiance caching arranges for the ratio between determined and interpolated rays, but does not set the amount of them (or density, per render area). This is done with the Indirect Light Quality slider, higher values make more rays shot into the scene for IDL, with longer render (that is: IDL pre-pass) times accordingly. It’s a percentage (0..100%) of something. For final renders, one could say: just set 100 for quality. This certainly might hold for large stills. On the other hand, slightly lower values render much faster without reducing image quality that much.

Speed vs Quality

So I did some additional research, rendering a scene with various settings for Irradiance Caching as well as IDL Quality. My findings are:

• * When either Irradiance Caching or IDL Quality is set below 80, the result shows splotches, while AO-sensitive areas (near hair, head/hat edge, skirt/leg edge, …) get too less light and produce darker shadows. These effects are noticeable for my eyes, I can tell them without knowing beforehand where they will show up in the result, and especially the splotches create low-quality impressions.
• * When IDL Quality is increased, rendertime only gradually increases while the splotches disappear. So this is some low coast / high result kind of improvement. Until the value exceeds 90, then the improvements are not really noticeable anymore.
• * When Irradiance Caching is increased, rendertime goes up fast, and say doubles till 90 is reached, and quadruples or worse when values get even higher. The main effect is on the quality of the (self)shadows in the AO sensitive areas, which I consider not the most relevant. So this is a high cost / low result kind of improvement, but for values up till 85 it also contributes to the splotch reduction.

So my preferred settings are 80 and up for both Irradiance Caching and IDL Quality, in any case. I tend to set IDL Quality to 90, and Irradiance Caching to 85 increasing to 90 depending on my findings in the specific render results.

The shorter render times can be relevant, especially when producing animated sequences. The best settings depend on the scene and require some experiments with a few frames, before rendering out the complete sequence.

Tips & Tricks

The Poser manual present some tips for handing IDL effectively.

• * IDL means light bouncing around, and performs best when the scene is encapsulated within some dome, or room, or enclosure. Especially the SkyDome might offer self-lighting as well.
• * Reduce the amount and intensity of (direct) lights, especially under SkyDome lighting conditions. One main light and one support light might be sufficient.
• * Smearing indicates the IDL is short of detail, so increase Irradiance Caching. Watch the red-dots prepass.
• * Splotchiness indicates the IDL takes too many samples, so reduce Irradiance Caching and increase Indirect Light Quality for compensation
• * Use Raytraced shadows instead of shadow maps, increase Blur Radius to say 10 (and shadow samples to 100, I like to keep the 1:10 ration intact).
• * Ensure Normals Forward is checked for all materials (this is the case by default, but anyway)
• * When using IDL in animations, render all frames in the same thread on the same machine. As said in the manual. Apparently, some random sampling and light distribution takes place when rendering, and this random process is seeded by thread and machine ID for various good reasons (as in: to avoid apparent pattern tiling and repetition within the render result). Unfortunately, multi-threading and multi-machine network rendering are essential for producing animations. So actually, the manual says: do not use IDL for animations. That’s a pitty, isn’t it? So I suggest to experiment with the settings, raise the Quality, consider to switch off Irradiance Caching (that eliminates at least one IDL related random sampling process, although it might be a rendertime killer), and evaluate some intermediate test runs. Things might be not that bad after all.

Some additional tips from my own experience:

• * Direct lights with inverse linear attenuation, and especially with inverse square attenuation, can create hotspots when put close to a wall, ceiling or other object. Those hotspots propagate through the scene presenting “light splotches” all around. Increasing Indirect Light Quality, raising (or unchecking) Irradiance Caching and taking light absorbing measures around the lights are some ways to go.
• * Sources of indirect light, being too small or placed too far away from the relevant objects in the scene, will produce lighting levels which are too low. This can present “shadow splotches” all around. Using large light sources nearby the object, and using direct lights instead, are ways to go.
• * Indirect Light works on Ambient and Diffuse only, and produces a serious amount of all-around ambient lighting, including Ambient Occlusion. But it does not work on Specularity, and it’s not very good in producing specific, determined shadows from objects. Using direct lights for those specific purposes instead is the way to go. As is “photography is painting with light and shadow”, IDL is a mighty tool for painting with light. For painting with shadow, use direct lights instead.
• * Lots of objects are completely irrelevant for bouncing indirect light around, they will not illuminate neighboring objects anyway. Test unchecking the Light Emitter option for those objects. Especially check on
  • * Skin. In various material settings, some ambient is added to mimic translucency (subsurface sampling) in older versions of Poser or to speed up the rendering. As a result, the skin will act as a light source under IDL. Switch it off.
  • * Hair. Lightrays can bounce around forever; it takes loads of time and resources, and accomplishes nothing. Switch it off, to speed up the IDL pre-pass. However, taking those surfaces out of the IDL loop might produce flat, dull results. In this case one either has to take the long render-times for granted, or one has to seek additional measures like adding in some extra AO for depth somehow.

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The Poser Firefly renderer presents us a shipload of additional settings, in order to sacrifice the resulting quality (a little bit) at the gain of better resource utilization (a lot). Do keep in mind that the renderer – based on the Reyes algorithm, from the last decade of the previous century – had to perform well on single threaded PC’s, running at a 100MHZ clock and memory banks in the sub-Gb range. Current machines run at tenfolds of those numbers, in all areas.

Image sub-resolution

Anti-Aliasing

Anti-aliasing (or AA for short) is a well-known technique to avoid jagged edges made by the individual pixels along a skewed line in the resulting image. AA introduces additional sub-pixels to be calculated around the main one, and then the color of the main pixel is derived from itself and its neighbors.

• 1, only the main pixel is taken into account, no Anti Aliasing takes place
• 2, the four neighboring pixels are taken into account, it requires 2 times as much pixel renders
• 3, eight neighboring pixels and the main pixel itself are taken into account, it requires 4 times as much renders This choice delivers “pretty good” results for any kind of electronic publishing (TV, Web, …)
• 4, sixteen neighboring subpixels are taken into account, requiring 8 times as much pixel renders
• 5, twenty-four neighboring pixels plus the main pixel itself are taken into account, requiring 16 times as much pixel renders. This one is blowing up your render time, and delivers “extremely good” result of any kind for high end printing. Especially in this area one has a choice between
  • a high pixel count (high dpi number, say 250) with modest AA (say 3) and
  • texture filtering (say Quality) settings, and a modest pixel count (say 125) with high settings for AA (say 5) and texture filtering (say Crisp).

The first can be expected to render longer with lower memory requirements: more render-buckets with less sub-pixels per bucket. Actually, I never use 5 for high end printing results: I prefer to render at a larger image size. So, the default value 3 is considered one that hardly needs adjustment: it does do AA, it takes the main pixel itself into account and is fit for all electronic and most print publication. Use 1 for draft renders, switching off AA in the results.

Micro polys

The basic routine of Firefly is to break a mesh down to micro-polys, which then are assigned a texture fragment, and are rendered accordingly. The Min Shading Rate denotes the minimum amount of pixels in the final render result that are covered by a single micro-poly. In other words, this setting sets a minimum size for the micro-polys and stops Poser from subdividing any further. Lower settings make better quality, and blow up memory use while rendering.

So, the value 0.1 implies that each micro-poly is (at least) 1/10^th of a pixel in size. At most, so this 0.1 relates quite well to the default “3 Pixel Samples” setting for AA. It does not make much sense – very specific scenes excluded – to keep the 3 pixels for AA while reducing the Min Shading Rate to 0.01 allowing at most 100 microploys per pixel in the final render. The extra information is not going to be used while taking up a lot of memory for the micropolys. Inversely, it does not make much sense to keep the 3 pixels for AA while increasing the Min Shading Rate to 1 allowing for at most 1 micropoly per pixel. Where is the extra information for the Anti-Aliasing coming from then?

Reasonable combinations seem to be:

• Pixels = 1, Min Shading Rate = 1.00 to 0.50 – good for drafts
• Pixels = 3, Min Shading Rate = 0.10 to 0.05 – the default
• Pixels = 5, Min Shading Rate = 0.02 to 0.01 – the extreme

Note that the Shading Rate relates the size of micro-polys to the size of pixels in the render result. This implies that when we set larger render dimensions, each original poly and object in the scene will get broken down to a finer granularity automatically.

Texturing considerations

Say, I’m rendering out to a 1000×1000 image result. In the middle, I’ve got a head, or a ball or any other object, which takes say 500 pixels in the render. To surround that object with a texture, that texture needs to be 1000 pixels in size to match the output resolution. Half of the pixels will show in the image, half of them will be hidden facing backwards. From information theory (Nyquist etc, sampling statistics) it is known that one should have a texture quality for input which is at least two times the quality of the output. Hence, the head needs a texture map of 2000 pixels in size, at least. And anything over 4000 might be overkill.

If the head takes a smaller portion of the resulting render I might not need such a large texture map, but when I consider to take a close up facial portrait, I might need more. Because when the resulting render of 1000 pixels shows only half the head (or more precise: 25% of the head as it shows half of the visible part facing the camera), then I’ll need 2 (Nyquist) x 4 (the 25%) x 1000 = 8000 pixels for a good texture map, which runs into the Poser limit of 8192 for texture sizes.

Also, when I consider larger render results, I might need larger texture maps as well. How does all this relate to the other findings above?

The 3×3 Anti-Alias requirement will subdivide the 1000×1000 render result into 2000×2000 subpixels, and this two-folding neatly matches the Nyquist pixel-doubling requirement for good texture maps. So the AA and the texture mapping are on the same level of detail. Since 5×5 Anti-aliasing can be seen as a limit, resulting in 4000×4000 subpixels, the fourfold texture sampling can be seen as a limit too. That’s why I said above: anything over 4000 might be overkill in that situation.

When an object is broken down to micro-polys, and one micro-poly matches more than one pixel in the texture map, and/or more than one pixel in the resulting render, we can imagine some loss of quality. So I want a few micro-polys per pixel in both cases. A Min Shading Rate of 0.5 gives me micro-polys of half the size of an output pixel which can be considered Low Quality (draft), but a value of 0.1 gives micro-polys of 1/10^th the size of an output pixel, which is enough to support a serious 3×3 AA requirement. Since a decent input pixel (from the object texture map) is 50% to 25% the diameter of an output pixel, I’ll have 4 to 16 input pixels covering the output pixels. A Min Shading Rate of 0.1-0.05 will generate say 10 to 20 micro-polys covering an output pixel. Good match. So this value is enough to support good texture mapping and offers a few micropolys per texture-map-pixels without being overkill.

Conclusions on Resolution

1. 1. The default settings for Pixels (3) and Min Shading Rate (0.1 – 0.05) are good for all quality results. Settings could be reduced to 1 / 0.5 for draft renders. Settings could be increased to 5 / 0.01 for high-end printing when increasing render size is not considered.
2. 2. However, for high end printing, increasing render size is the preferred route over raising the settings.
3. 3. Object texture maps should offer at least 2, at most 4 times the render resolution. That is: an object which takes 50% of the render width / height should be surrounded by a texture which offers at least twice as much pixels (width/height) as the resulting render.
4. 4. This way, Render resolution, Texture resolution, Anti-alias rate (pixels) and Min Shading Rate are mutually balanced, all supporting the same quality level.

Divide & conquer

In order to handle the rendering by a multi-core, multi-threaded machine, each render is chopped in pieces; the buckets. Each bucket delivers a square portion of the result, say 32×32 pixels, although at the edges of the render the buckets might be less wide, less high, or both (in the corner). Each bucket is handled as a single thread CPU process with its own set of memory, addressing its own set of objects in the scene. And when there are either too many threats running in parallel, or each thread takes too much memory as it’s too crowded or too textured, on might face memory issues while rendering.

Max bucket size

In order to address these issues, one can either reduce the amount of threads running in parallel (in the Edit > General Preferences menu, Render tab) or the Bucket size. One might expect that halving the bucket size reduces memory requirements to 25%, while quadrupling the amount of threads required to perform the render. The latter won’t make a difference as each thread handles just 25% of the previous render size. In reality, neither will be the case, because the bucket-rendering takes some objects from neighboring buckets into account by adding a (fixed width) edge around it: the bucket overhead.

For example: Say the bucket-edge is 8 pixels wide, and I consider a 64×64 bucket, then it will render (64+2×8)² instead of 64² pixels, that is 156% of its contribution to the result. But when I consider a 32×32 bucket, it will render (32+2×8)² instead of 32² pixels, that is 225% of its contribution. So resource requirements will be 225/156=144% higher than expected. Memory demands will not drop to 25% but to about 35%, while rendering will take say 45% longer due to overhead increase. When I consider a 128×128 bucket instead, it will render 126% of its contribution, memory requirements will go up 4*126/156 = 324% instead of 400% while processing will take 126/156 = 80% of the time – that is for the rendering part of it, not the preparation passes for shadow mapping, and SSS or IDL precalculations.

So reducing bucket size should be done when facing memory issues only, and even then the question is whether such should be done manually. This is because the value entered in Render Settings is a maximum value. Poser will use it as a limit, but will reduce the bucket size dynamically when facing excessive resource issues. So altering the value is a manual override of the Poser behavior, which only makes sense when Poser itself falls short.

On the other hand, increasing bucket size will have some flaws too. When the rendering is chopped in too few pieces, you will soon run out of threads to load your CPU cores, and they remain idle till the last one is finished. In other words: your CPU resources are used less efficient.

My recommendations:

• * On a 32-bit system, use 32 for most renders but reduce to 16 for very crowded scenes or increase to 64 in scenes with just a few figures and props.
• * On a 64-bit system, double those values, and double again when there is plenty of RAM available.

A note on render hotspots

Some renders present a spot in the image where rendering takes all the time, that one bucket is slowing down the entire process. Reducing bucket size maybe of help then, when it concerns an area that can be distributed over multiple threads. When it really concerns some kind of small spot, even the smallest bucket will hold up everything, and reducing bucket size is not the solution. It’s not causing harm either, though, for that render.

The question is: what is causing the hotspot, and are other cures available? Sometimes, object- or material options might be reconsidered:

• * When it concerns hair, conforming or dynamic, it should have its Light Emitter property checked OFF This might affect the quality of the rendered hair, in which case compensation-method should be considered. Something which adds in AO for a bit extra depth, perhaps.
• * Some shiny surfaces, like teeth, could do with specular only and don’t need full reflection

Things like that.

Max displacement bounds

Displacement mapping might change the size of an object. Poser has to take this into account in order to determine whether or not an object is relevant for the rendering of a bucket, even when the object itself resides outside the bucket area. The object-size should be increased a bit, then. Poser does a decent job in doing so, using the material settings, and using the bucket edges as discussed above, but might fall short in cases. In those cases, the details of the displacement seem to be chopped off at the boundaries between buckets.

Note that both Min Displacement Bounds and object Displacement bounds both are in Poser Native Units, whatever your Unit settings in the General Preferences. 1 PNU = 8.6 feet = 262.128 cm, or: 1 mm = 1/2621.28 = 0.0003815

Image handling

Toons

The Poser Firefly render and material system offer loads of options to produce photoreal results: Subsurface Scattering, Indirect Lighting, Focal and Motion Blur to name a few. On the other hand, the shader tree offers a Toon node, and the Render settings offer an outline function. In my personal opinion, mixing the Toon and the Photoreal options gives some misplaced feelings. One might need reflections, and some softening of shadows and highlights in a toon render. But does one need Subsurface Scattering and Indirect Lighting? Your render, your call.

Sharpening

Of course one can sharpen render results in post, but the filter presented here is applied in an earlier stage: while the result is build up from subsamples, like anti-aliasing. Anti-aliasing will blur the render a bit to take the jags out of the edges, but that affects the fine textured areas as well. The filter brings back those details to some extent.

The values mean:

1. 1. no filtering
2. 2. limited sharpening, fine for female skin, rough outdoor clothes and textures with mild detail
3. 3. stronger sharpening, fine for male sin, fine indoor clothes, short animal fur, lots of detail and the like
4. 4. extreme sharpening, disadvised

As the purpose of sharpening is: to bring back the details and color contrasts from the texture maps into the resulting render, the SINC option performs best.

SINC, filtering 1	SINC, filtering 2	SINC, filtering 3	SINC, filtering 4

Snakeskin texture, from not filtered (left) to overly sharpened (right).

Tone mapping and Gamma Correction

Correcting images for Gamma and Exposure is a world in itself; I dedicated a special Understanding Corrections tutorial on this.

Exposure Correction, or: Tone Mapping, can be done in post as well for still images, and in most cases it’s not used. Doing it in Poser is a benefit in animations, as it’s applied to all frames on the go.

Gamma Correction, available in Poser Pro 2010 and up, and Poser 10 and up, is a different story. It works rather different from alike processes in post. It hardly affects the main colors in the render result but it certainly softens the highlights and shadows from lighting and shading the objects around. To some extent, Gamma Correction (GC) as implemented in Poser is a way to deal with the far too strong effects on shadows and highlights from the infinitely small direct lights, as used in 3D renders. But so is Indirect Lighting (IDL). This leaves the question whether two steps in the same direction are not just one too many. Should GC and IDL be used in combination, or should one use either the one or the other?

Well, in scenes using IDL, additional direct lights usually provide specularity (as IDL cannot provide this). They also provide local lighting effects, like photographers are using flashes and reflectors to brighten up their shots. In those cases, GC does have a role too. Also, IDL mainly affects the overall lighting level in the scene when large objects, especially a SkyDome, are emitting light all around. In those cases, GC might not have a role. So, the extent to use GC in IDL lit scenes is up to you. You might go for the full amount (value 2.20), or for none at all (switch it off, or set the value to 1.00), or for somewhere halfway (set the value to 1.50 then, or try 1.20 or 1.80 instead).

Saving results

Poser stores its render results in 16-bit per color (48 bit per pixel + transparency) EXR files, in
C:\Users\(your account, might be admin)\AppData\Roaming\Poser Pro\10\RenderCache

Poser can translate those when exporting to the 8-bit per color BMP, TGA, JPG (all without transparency) and the TIF, PNG or even PSD (all with transparency) format, and the 16-bit per color HDR or EXR format (Poser Pro only). Lossy formats like JPG are recommended only when the render does not require any additional post processing anymore, otherwise the lossless TIF, PSD and hires HDR or EXR are recommended instead. Saving to lossy formats should be the final step.

After rendering, the final result is dithered a bit to eliminate banding in subtle gradients and various antialias situations. For the results exported in HDR/EXR format, this is something unwanted, as it might intervene with additional processes in post. The render setting HDRI-optimized output skips this dithering when checked. Note that this will lead to suboptimal results when exporting in any 8-bit per color format.

Poser Pro also can export various aspects of the render separately, like Diffuse, Specularity, Depth and more. This is behind the Auxiliary render data option. This way, all those aspects can be merged in post. Merging in the shadows was already discussed above in this tutorial. More on this in my separate tutorial on Poser Render Passes.

Other options

Presets

One can define a series of settings for various steps in the workflow (draft, intermediate, final for web, final for print), and for various types of result (Toon, Photoreal, …). And then save and load those settings as presets.

Raytrace Preview

Progressive Mode is a new option to Poser 10 / Poser Pro 2014. It greys out various options from the render settings, and leaves a few which affect the result of the Raytrace Preview window. The ones greyed out will get a standard setting or value, the manual does not tell us which.

Do note that when Progressive Mode is left switched ON when rendering, those standard settings are used for the render result as well. This presents you a result which is a larger version of the contents of the new Raytrace Preview window. Switch Progressive Mode OFF to enable the other options again.

My personal observation is that this Raytrace Preview does not work out very well with IDL lit scenes. It does give some clues on the lighting levels, but the result itself is far too coarse for anything else. It does work out great in diret lighting though, and… it’s a Raytrace Previews after all, not an IDL Preview.

Launch

From the Render Settings window one can call for the Render Dimensions (= size of the result) dialog, as the similar Poser menu option is out of reach when the Render Settings window is active. Also the rendering can be sent to Background or to the Queue (Poser Pro), instead of running in the foreground. Or the settings can just be saved. That is: to be used when clicking the Render button at the top right of the Document window.

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