Poser lights have their shortcomings, when I want to use them as lamps in real life. Poser lights are extremely small, therefore they produce very hard shadows, and they lack the atmospheric scattering which is always present in real-life environments. And… real-life behavior takes lots of resources when rendering. All this can be compensated for.

Shadow Bias

Then we’ve got the magical Shadow Minimum Bias property, what does it do and why?

Well, technically it takes a shadow casting surface, shifts it a bit towards the light, calculates the shadows onto that uplifted surface, and then assigns those shadows onto the actual shadow casting surface in its original position.

The advantage comes when handling displacement maps and small scale surface detail. Without the bias, every detail has to be taken into account as it warps a tiny shadow onto the surface. Those shadows are quite unnatural, such minor irregularities don’t warp shadows at all. The light bends around them, and the scattering in the atmosphere will make the thin shadow fade away. Besides that, it’s an enormous job for the shadow calculations. With the bias, only details that rise (or sink) more than this value will be taken into account. This enhances the natural feel of the shadows and it saves processing effort as well.

The downside is: it creates an artifact as the shadows themselves are somewhat displaced relative to the objects. To a minor extend, this is acceptable but larger values produce notoriously incorrect results.

Actually, the default 0.8 is quite a lot already so in my opinion one should never exceed 1. On the other hand, 0 cracks the renderer so 0.000001 is the real minimum here and will make shadows from every surface detail. Perhaps 0.1 would be a nice setting.

Ambient Occlusion

Direct lights warp direct shadows, either mapped or raytraced. Indirect and Image based Skydome lights generate an omnipresent ambient lighting which hardly warps shadows at all. But that is incorrect, as in my room the lighting level under my chair is much higher than that under my PC cabinet. Objects and surfaces close to each other hamper the spread of ambient lighting, they occlude each other from the ambient light.

In the early days of Poser, this Ambient Occlusion (or: AO) was dealt with as a material property, hence the Ambient_Occlusion node in the materials definition. Actually this is weird, as AO is not the result of a material but the result of the proximity of objects or of object elements (hence: the shape of an object). Above that, AO is mainly relevant to Diffuse IBL lights which generate the shadow-less omnipresent ambience.

More on that later.

Light arithmetic

In real life, when light shines on my retina or on the backplane of my camera, one light shining at a surface fires some percentage of the light-sensitive elements. A second light then fires the same percentage, of the remaining elements. As a result the non-fired elements reduces to zero when adding lights, and the captured lighting level increases to 100%. Photoshop (or any other image handling program) does a similar thing when adding layers using the Screen blending mode.

Poser however just multiplies and adds up. A 50% white light on a 50% white object results in a 50% x 50% = 25% lighting level. A 100% white light plainly lighting a 100% white object results in 100% lighting level. Two of those 25% lights make a 50% lighting level, or in the second case: a 2x 100% = 200% lighting level in the render. And this latter will get clipped (back to 100%) when establishing the final output, resulting in overlit areas. As in the first case, five lights on a grey object will cause overlighting too.

Things will be slightly different when Gamma Correction is applied. Then, first, all lights and objects will get anti-gamma-corrected (darkened), let’s say the 50% reads as 20% then, but 100% stays at 100%. In the latter case, nothing changes: one light on a white surface makes 100%, two lights make an overlit area in the render. The first case however produces a 20% x 20% = 4% lit area, two lights make 8% (Poser still just adds up), and now that intermediate result is Gamma Corrected to say 35% instead of the 50% without GC.

But even 24 lights add up to 24 x 4% = 96% which gets Gamma Corrected to 98% in the final result, in other words: Gamma Correction prevents – to some extent – severe overlighting. Actually it dampens all effects of lighting and shadowing.

Light materials

Poser direct lights appear in the Material Room as well, having Color, Intensity, Diffuse and Specular as the main parameters. Other parameters mainly serve legacy situations and can be discarded.

Color and Intensity team up (multiply) to fill the Preview, and give me light on my work. While rendering, the Diffuse and Specular channels kick in as well, and multiply with the Color x Intensity just mentioned.

This implies that blacking out the Diffuse make it turned off for diffuse lighting in the render, while still lighting the preview, and making specular in the render as well. This is great when working with IDL lighting which caters for all diffuse lighting itself, but fails to light the preview and does not produce specularity either. Similarly I can produce lights that make diffuse light only, with the Specular channel blacked out. Or lights which contribute only to the preview, having both Diffuse and Specular blacked out.

I also can have strong lights in the preview but have them dimmed in the render, by having reduced intensities (grays) in the diffuse and specular channels. And I can confuse myself a lot, by using some white hue in the preview but using some color while rendering. I never do that, though.

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Poser offers several types of direct lights: Point Lights, Spot Lights, Infinite Lights and ImageBased Lights. Poser does not offer Area Lights, nor shaped lights like neon texts, as a direct lighting source. These can be emulated by Indirect Lighting techniques, which are discuscced in a later chapter.

Point Lights

A Point light differs from an Infinite light in just a few ways. First, is has a location X,Y,Z and so it has a distance to figures and props in the scene. As a consequence, attenuation and distance related intensity falloff can be supported. In the light properties, for a start. Constant means: no drop, like the infinite light. Inverse Square means an 1/x² or: following physical reality for a singular light bulb. Inverse linear means 1/x which is just somewhat in between, a bit like the falloff from a lit shopping window or a long array of street lanterns.

The Constant attenuation works with the parameters Dist_Start and Dist_End.

These imply that the intensity drops from full to zero – linearly – in the given distance range. In this example, a 100% light remains so until 5mtr, and then drops with 20% a meter till after another 5 mtr there is no intensity left.

Note that this distance-drop works for Pointlights as well as Spotlights (even if the title says: Spotlight), and works for Constant attenuation only. Inverse Linear or Inverse Square attenuations remain as they are, they do not respond to this extra distance drop. When Start as well as End are set to 0, there is no drop, which is the default.

Spot Lights

In addition to Point lights, Spot lights have an additional “light beam width”. The light is equally intense in all directions, then drops off (linearly) from the Angle_Start to the Angle_End.

Personally I don’t understand the default, who wants a gradual falloff from the heart of the beam to 70°? When the flaps could open up to 180° then the spot would turn into a point light, but they can’t: 160° is the max. In reality, 80° to 90° might be a decent maximum. I guess real light dims within 20°, so flaps at 80° would suggest an angular dropoff from 70° to 90°.

Spotlights are the ultimate candidates for making beams in fog and other atmospheric effects. This is dealt with in the chapter in Poser Atmospherics, later in this tutorial.

Bulbs and Window Panes

In the real world, lamps are not infinitely small. Lamps may come as bulbs (say half to one inch radius), but also might be as large as a shop window, or even a street full of shop windows.

Very close to the light, there won’t be any falloff when we move gradually away. Very far from the light, every lamp becomes a point light and will have inverse-square falloff. This is illustrated in the graphs, the green one presenting inverse square, the red one a lamp with some real size.

For a disk-shaped light source (as a point light with some size at a distance) with radius R lighting and a sensor at distance d, the light captured by the sensor is directly proportional to

{ 1 – 1 / sqrt[1+ (R/d)²] }

From the graphs it becomes apparent that when the distance becomes more than twice the radius of the lamp (value 2.0 on the horizontal axis), this falloff behavior becomes about the same as ideal inverse square falloff (red and green curves match), and hence the lamp can safely be considered a point light.

Window panes – although not circular – will not be that different. I can use half the average of width and height for “radius”, and I can use a distance : size ratio of at least 3 or even 4 to be on the safe side when I want to. But at least I do know that for distances larger than say 3 times the window size, the inverse square law holds pretty well, while for distances smaller than say half the window size, any falloff better can be ignored.

Light Strips and Softboxes

Photographers use softboxes (square-ish) or lightstrips (quite elongated softboxes) instead of flashes, for the simple reason that the larger the light, the softer its shadows will be. So softboxes are a nice way to simulate environmental, ambient lighting while flashing under studio conditions.

Something similar holds for Poser lighting as well, and one might like some softbox equivalent in the 3D scene. Unfortunately, Poser does not support Area Lights, which would be ideal for this.

This leaves two alternatives: I can make one from a glowing rectangle under IDL conditions, or I can stack a series of direct (spot)lights together in a row or matrix. Indirect or direct lighting, that’s the question. The first option will be investigated later in this tutorial. The second option takes one spotlight, flaps wide open, in the middle and four around it at the corners. Of course one can make up larger constructions, but it’s doubtful whether that pays off. Parenting the corner-ones to the middle one enables me to use the shadow-cam related to the middle one for aiming the entire construction.

Then I’ve got to adjust the lighting levels, and make sure the sum of the intensities matches the original intensity (or just a bit more, to compensate for the corners-lights at some distance of the main one). Like 10% (middle) + 4x 22,5% to make 100%, or 15% + 4x 30% = 135%. Next to that, I adjust the shadowing (raytracing, blur radius 20, samples 200) to soften the lighting even further, as I can reduce the shadow parameter itself to say 80%.

What is a good size for softboxes? Well, photographers are quite clear about that. A good box is at least as large as the object to be pictured, and placed at a distance at least once, at most twice the size of the box itself. So, for the mildly zoomed out result above, the 2×2 mtr software actually is too small, and probably a bit too far away as well.

Should I set attenuation for the lights? Well, an object so close to the softbox should be considered as a person standing in front of a shopping window. And in the paragraph above on window panes I argued that the range between one and two window-sizes meets the transition area between no attenuation (till say half the window size) and neat point-light-like inverse square attenuation (from say three window sizes). So I can pick inverse-linear as a go-between or use the Dist_Start and Dist_End parameters for each lamp to ensure the softbox is working on the object only, and is not lighting the background, as is done in real life too.

Diffuse IBL

This technique is a first attempt in the graphics industry to make a) better environmental lighting and b) create lighting in a 3D scene which matches the colors and intensities of the light in a real scene. The latter is required to make a smooth integration of 3D elements into real-life footage.

First, this technique uses an “inverse point light”, that is the light rays in the 3D scene will be treated as generated from an all-surrounding sky dome – which is not really present in the scene – towards the IBL Light. Or: the IBL-light is the “source’ of light rays which are treated as travelling inward. Whatever view fits you best.

Second, all those light rays get their color and intensity from an image map. When this image map is folded around a tiny sphere at the place of the light, then each point on the sphere presents the environment, sky as well as ground, when looking around from the center of the sphere. The image map can be obtained by taking a picture of such a (very reflective) spherical object in the real life scene.

Indoor sample

Outdoor sample

So one also can say: the IBL light projects the image map onto the (imaginary) sky dome in the 3D scene which then re-emits that light back to the IBL.

In the meantime, the industry has developed the concept further, and especially tried to replace the reflective ball by panorama photography and multi-image stitching, or by other types of mapping the obtained images onto the IBL, aka the virtual sky dome.

Cube mapping

Panorama

Angular map

Mirrored ball

Poser Diffuse IBL (Image Based Lighting), works in the Diffuse (Reflection, etc) channels but not in Specular (nor Alternate_Specular): Poser IBL lights cannot produce highlights, I need one of the other direct lights for doing that.

Poser IBL is quite good in creating an ambient, environmental lighting in a fast way. As a result, it’s not so good in creating a similarly improved, matching shadowing. This introduced the need for AO, Ambient Occlusion, the shadowing of ambient, environmental lighting which makes it darker under tables and cupboards, and generates self-shadowing in objects with a complex geometry.

In Poser, and in lots of other programs, the developments continued. And so did the processing power in our PC’s. This introduced IDL, Indirect Lighting, with sky domes or other scene-enclosures which radiate light by themselves into the scene, and which can be textured in the regular way. Fading out IBL as a lighting solution.

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Indirect Lighting, aka IDL, is a computational intensive lighting strategy which can be considered the successor of IBL, Image Based Lighting. The use of it can be switched on/off in Render Settings. The basic principle of IDL is that loads of light rays travel around through the scene, hitting objects, and be re-radiated by those objects again usually with an adjusted color and intensity. This supports ambient lighting, indoor lighting from outdoor sources, radiating objects, radiosity (colors spilling over to neighbor objects) and proper mild shadow levels.

For a start, just a collection of notes and remarks:

• * IDL is a successor of IBL, easier to use but far more computational and memory intensive. So, when IDL is not really working for you in a specific scene or on specific objects, consider re-introducing IBL as an alternative.
• * Like IBL, IDL is working on Diffuse channels only, including Reflection, Refraction, Alternate_Diffuse. It is explicitely not working on Specular (and Alternate_Specular, and any specular material node wherever in the shader tree).
• * IDL lights do not show in preview. As a result of this, and of the previous point, consider to use direct light in the scene with the Diffuse disabled (blackened out). And eventually, with Specularity blackened out too.
• * IDL renders best (for final results) with Irradiance Caching ON, value at least 80 at most 90, and with IDL ON, Quality at least 80 at most 90. Lower values introduce noticeable splotches all-over the image, and overly dark shadows in self-shadowing areas. Higher values take a lot of time and resources while not adding noticeably to the result.
• * It should be clear then that IDL does require raytracing to be active. This also introduces another mechanism to let the light rays die: when the limit for bounces is met, as set in Render settings, Poser cuts off any further handling of them. This will darken the ambient lighting, might introduce artifacts, and is explicitly meant for speeding up draft renders. Please set Bounces to the max when making your final render.

An interesting point is: I can launch the rendering from the Dimension3D menu too, and get access to additional settings. Indirect Light does have its own Bounces and Irradiance Cache, next to the generic ones for AO and reflection / refraction.

• * IDL renders best when the scene is enclosed by a sky dome, walls of a room, or anything alike that traps the light rays and keeps them bouncing around.
• * IBL comes with AO (Ambient Occlusion) to improve on shadowing from ambient, environmental lighting. Any other direct light should have AO switched off. Also, AO should be off under IDL conditions as IDL generates its own shadowing. Again: AO is for IBL only.
• * IDL lighting can be switched off per object, by switching (off) the Light Emitter property of that object. This is worth considering: * for Skin, as Ambient is used sometimes to mimic translucency and subsurface scattering in a fast way, for the older Poser versions. Don’t let your characters be a light source, switch Light Emitter off. * for Hair, as light rays will bounce around forever requiring about infinite render times without adding much to the result. You will then lose the ambient lighting and additional shadowing for that object; it might look a bit flat. Think IBL + AO as an alternative.
• * As the environment is supplying a lot of light, either by bouncing direct light around or by adding light from glowing objects (and especially: all-surrounding sky domes), I need far less lights and far lower intensities compared to non-IDL scenes. As a consequence, all the advanced lighting rigs constructed for non-IDL scenes – emulating environmental lighting with lots of direct lights all around, won’t serve very well any more. All I need is a glowing dome for sky, an infinite light for sun, and perhaps one or two spots for support and flash.

Radiosity

Objects which catch light, re-emit light after merging in their own colors, and reducing intensities. This makes a bright red ball warp a reddish light around, noticeable on white floors etcetera.  This is the basic principle of Indirect Lighting and served automatically when this lighting mechanism is enabled. The re-emitted light then is used in all further IDL lighting as well, the light rays either die from energy loss or from being captured by the camera (or by being killed by Poser when Bounces is set low).

Light Emitting Objects

In order to use IDL, I need at least one light emitter which sends out rays. This can be a regular direct light, like point, spot or infinite. Such a light is required anyway for creating specular effects and additional shadowing, but for (diffuse) lighting itself I don’t need direct lights at all.

I can make an object glow, by assigning it a high level of Ambient as a material, and it will serve as some lamp immediately. The larger the Ambient_Value, the higher the intensity of the light, the stronger the lamp.

Two balls, one glowing, IDL off, no direct light

Same scene, IDL on

Same scene, IDL, extra direct light on

Same scene, IDL off

Note the strong shadows in the rightmost image, which lack in the third where the white floor is bouncing the direct light, reducing the shadows at the lower back/right side of the white ball. The second image shows shadows from the right ball onto the floor caused by the glow/lighting from the red ball at the left, and also demonstrates the lack of specularity (highlights) in IDL lighting.

Sky Domes

IDL works best when the entire scene is embedded in some kind of enclosure, like a box (walls, floor, ceiling for indoor shots. For outdoor shots, the answer is: a sky dome. I could use a normal (hires, half a) ball at a large scale, but dedicated sky domes have even a larger resolution (more polys to reduce smoothing artifacts) and have their normal pointing inward which generally is not the case with regular objects. And I can apply a texture to the dome to obtain the lighting conditions as were, or could be, present in a real life scene. Large shots from landscape generating software, like Vue, serve pretty well here too.

Note that the Diffuse material channel will “reflect” the regular lighting in the scene, and the Ambient channel will make the dome glow by itself. The latter is the usual response to sunlight, scattering through the atmosphere. The sun itself is best represented by an infinite light, within the dome. Then I raise Ambient_Value to get the proper intensity for this generic atmospheric lighting.

When the sky dome is used for color and intensity of the indirect light, scattering all around, the resolution of its texture map is not an issue. But that leaves the question: is the texture on the sky dome fit for purpose as a background image? Usually, it’s not.

Consider a camera at normal lens settings, that’s 35mm focal length and 40° Field of View (see table below), taking a shot (render) of 2000 pixels wide. The full sky dome, being 360° all around, then would require 360/40 = 9 times my view. And good texturing practices require at least double the resolution of my render. So the sky dome should be assigned a 2x 9x 2000 = 36.000 pixels wide texture, at least. Note that Poser takes 8.192 for max texture size, and you know you’re stuck.

Note that the size of the skydome – or any other 360° environment – does not matter. The Field of View matters, as a shorter focal length (typical for landscapes, say 20mm) increases FoV to 60°, and reduces the required texture to a 2x 360/60 x2000 = 24.000 pixels width.

Focal length (mm)	10	20	30	35	40	60	90	120	180
Field of View (°)	90	60	45	40	30	22,5	16	12	8

So the bets are that you’ll end up with say 8000 pixel wide panoramic image for the skydome, which is too low a resolution for proper background imaging, plus some background image prop holding another 2x 2000 = 4000 pixel wide portion of the high-res version of the panorama just covering the left-to-right edges of the rendered view.

Since this billboard prop might block the skydome lighting considerably (ensure it does not cast shadows, highlights etc) when placed nearby the dome it might need to serve as an active light emitter, the same way the skydome does. When the prop resides at some distance from the dome however this might not be necessary, so you’ll have to test for this a bit.

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