Lights and Shadowing

Sasquatch fur and hair can receive shadows from LightWave objects, cast shadows onto LightWave objects, and self-shadow. You can activate and deactivate each of these distinct abilities independently.

You can also control which lights affect fur, and boost or dim their effect on fur without affecting the rest of your LightWave surfaces.

"Special" Light Selection

If you want a light (or lights) to have a brighter or dimmer effect on fur but don't want to affect LightWave surface lighting, you can use Special Lights. When you choose one or more lights with this control, those lights can be individually "boosted" to make the fur react more (or less) strongly to them. The Special Light Strength value defaults to 100%, but you can set it to 0% to make Sasquatch hair ignore the Special Lights. You can make the lights affect the surface more than normal by using a higher value like 150%.

The lights that are not picked as Special also have a boost setting. This is particularly handy when all of your fur in the scene is simply too bright or too dim. You can simply change the Remaining Light Strength to boost or dim all of the fur's lighting. This is an extremely common and easy adjustment.

You can make lights that don't affect your LightWave scene, but do affect fur with a simple trick. Make the LightWave light intensity very dim, perhaps 1%. Then use the Special Light boosting to make the light 10000% brighter, and it will fully illuminate the fur, yet be virtually invisible to LightWave surfaces.

Receiving Shadows

LightWave objects will cast shadows onto your hair and fur if you activate the Receive LightWave Shadows button. This will cause Sasquatch to ask LightWave for shadowing information. This will slow down rendering, especially if you're using raytraced shadows in a complex scene. This option also often invokes a LightWave multithreading bug, which can usually be avoided with the Use LW Threading Bug Workaround button.

Shadow Casting

You can specify which light(s) are able to cast fur and hair shadows. These shadow casting lights must be spotlights since Sasquatch uses a shadow map. The Self Shadowing and Enable Cast Shadows buttons activate Sasquatch shadow casting as described in the next sections.

When you activate either shadowing option, you can choose which spotlights will cast shadows with the Cast Shadows From button. By default, all spotlights will cast shadows, but you can also manually choose individual lights if you wish.

Shadow Map Resolution controls the quality of the shadow maps. Higher values will use more memory and take slightly longer to render (though usually not much.) The total memory used by all of the shadow maps is shown so you can judge if you're wasting too much RAM. If the shadow map is not large enough, shadows will be blurry and won't show sharp details.

Like LightWave's shadow maps, you should carefully set your spotlight's cone angle to encompass your scene as tightly as possible. If your cone angle is too large, Sasquatch will waste RAM making a shadow map for the empty edges of your spotlight's cone. If the cone is too small, it won't illuminate your whole object. You can compensate for a large cone angle with a larger shadow map resolution. It's usually best to use Layout's Light View to look "through" the spotlight, then interactively adjust the cone angle to be as small as possible yet still cover the scene with light. If your shadows have a "checkerboard" or diamond pattern, your shadow map is too small or cone angle too large.

Self Shadowing

The best fur and hair nearly always uses self shadowing. The rich, deep, feel of fur comes from the complex way that light reacts to it. If the fur doesn't cast shadows onto itself, it feels very bright, and looks like glowing string instead of real fur. It's not wrong to always make all lights self-shadow fur. You can make different fur surfaces have different reactions to self-shadowing with the Self Shadow control in each object's Sasquatch panel.

The behavior of the self-shadowing is controlled in the pixel panel. Self-Shadow Softness controls the blurriness of the shadows that fall onto other hairs when self-shadowing. The default value of 10% is rarely changed, but you can experiment to see how it affects your rendering if the fur doesn't feel "deep" and fully 3D.

The quality of the self shadow effect can be changed by using Self Shadow Quality, which (of course) will slow down rendering slightly at higher values. This is mostly used for animation, where you may see flickering shadows if the quality is too low.

Radiosity and Caustics

LightWave 6.0 introduced radiosity and caustic lighting. In LightWave 6.5 and later, Sasquatch can respond to these lighting types if you activate the Radiosity Shading option. Unfortunately, LightWave's radiosity can be very slow, so this option will often increase rendering time dramatically. In LW 9.5 and beyond you need to turn on the "Volumetric Radiosity" option in the LW Global Illumination panel in order for Sasquatch to respond to Radiosity settings.

Fur Shadows on LightWave Surfaces

Unfortunately LightWave doesn't know about shadows that it doesn't make itself. But of course we want Sasquatch to cast our hair shadows onto LightWave objects! Luckily, there's a way of fooling LightWave into showing Sasquatch shadows by using the Sasquatch surface shader, called "Shadow of Sasquatch." Apply this plugin to the surface(s) that you want to have hair shadows cast onto. If you are using other plugin textures, Sasquatch should be applied as the last shader in the list.

You must also activate Enable Cast Shadows in the pixel panel, and select the light(s) that will cast fur shadows.

You can control the appearance of the shadows in several ways in the shadow shader panel. Shadow Opacity sets the darkness of the fiber shadows. The default of 100% makes fully black shadows. If you want to see some light even in a shadow, you can decrease this number to make the shadows less intense.

You can control the softness of the shadow (just like LightWave's shadow maps.) The Fiber Shadow Softness control will blur the shadows. As described at the start of this chapter, very sharp shadows are sensitive to the shadow map resolution and light cone angles.

You can increase Fiber Shadow Quality to make smoother shadows, though this may slow rendering slightly. If the quality is too low, you may see small artifacts that look like speckles or noise on your surface. This doesn't change Sasquatch's RAM usage at all, just speed.

Because LightWave doesn't pass some information to plugin shaders, the LightWave surface "Diffuse Sharpness" and "Color Highlights" options are ignored.

Luminous Shadow Darkening

A special feature of Sasquatch shadow casting is called Luminous Shadow Darkening, This is a tool usually used for compositing. It removes all surface shading completely but still allows shadows to darken the surface. This is great when you're trying to do something like cast a shadow from a wolf onto the ground. Using a photograph of the ground, you can make the wolf's shadow darken the image, but leave the lit parts unchanged.

When you activate the Luminous Shadow Darkening Mode button, the unshadowed parts of your surface will show the unchanged RGB color of the surface. Shadowed areas will be dimmed towards a dark shadow color. You can even choose the color with the Shadow Color control.

Final shader Options

The final shader option, Use Special Light Strengths, allows you to make the surface react to the same light boosting and selection (from Special Lights defined in the pixel panel) that hair and fur do. This is convenient when you want to use small lights to carefully illuminate fur but you don't want them to affect all LightWave surfaces.

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