Light Palette

From ZBrush Info

About Lighting

Because a ZBrush scene has depth and material properties, virtual lights are required to illuminate the canvas. ZBrush calculates shading based on the number, type, strength, and position of the lights in the scene.

Adding and Adjusting Lights

You can place up to eight lights in a scene and change their properties at any time. All lighting properties are saved with the ZBrush scene file. By default, ZBrush has two lights placed in the scene.

Lights are selected and positioned using the thumbnail part of the light palette, as shown below.

Click on a light to select it, and click again to turn it on or off. Click on the color patch to the left of the Intensity slider to cause the light color to be set to the primary color, or click and drag from the color patch to any other part of the screen to set the light’s color to the color under the mouse cursor when you release the mouse button.

The placement sphere in the upper left of the palette shows where the currently selected light is placed, and also shows the combined effect of all lights currently turned on. Drag the small yellow rectangle to change the placement of the current light; click it to toggle it from a front light to a backlight, or vice versa.

Lighting setups may be saved as ‘.zli’ files and restored in later ZBrush sessions. To save lighting setups, or recall them from saved files, use the Load and Save buttons at the top of this palette.

Global Light Mapping

Global light mapping is an efficient way to reduce the amount of system resources needed to light and render a scene. One global light map can replace many lights or free them for other tasks. You can use global light mapping alone or in addition to normal lighting.

The interface for global light mapping consists of diffuse and specular map previews and their associated intensity sliders:

Load a bitmap in either by clicking the preview window and choosing an image from the expanded texture palette that appears.

To make maps that can be used as described above to replace existing lights, create diffuse and specular bit map images:

1. Light your scene with as many lights as needed.
2. Make a new layer. See Layer Palette.
3. Hide the first layer and draw a white sphere with Material:BasicMaterial applied. See Material Palette. (You may want to do this with a copy of the BasicMaterial. See Material:CopyMat.)
4. Reduce the Material:Modifiers:Ambient value to zero.
5. Reduce the Material:Modifier:Global Ambient value to zero.
6. Reduce Material:Modifiers:Specular value to zero.
7. The white sphere, lit by your lighting setup, provides all the information needed for diffuse light mapping. Capture the scene with the MRGBZ grabber. (See Tool:MRGBZ Grabber.) The bit map will be added to your Texture palette.
8. Load the diffuse map by clicking on the diffuse map preview in the Light palette and choosing the map you just created.
9. Reduce the Material:Modifiers:Diffuse to zero and return Material:Modifiers:Specular to its previous value.
10. The white sphere, lit by your unique lighting setup, provides all the information needed for specular light mapping. Capture the scene with the MRGBZ grabber. The bit map will be added to your Texture palette.
11. Load the specular map by clicking on the specular map preview in the Light palette and choosing the map you just created.
12. Hide the current layer and activate the original layer.
13. Turn off all lights. Increase Light:Gdi and Light:Gsi until you duplicate the effect of normal lighting.

Using Global Light Mapping with existing lights

You can create interesting effects by adding to your existing lighting. For example:

Adding a diffuse light map at 50% intensity

Controls

All of the properties that follow (except Global Ambient, Global Diffuse and Global Specular) are set for each selected light.

Light Color (color patch): Set by selecting a color with any of the color pickers and clicking on the color patch. You can also click and drag from the patch to the canvas to pick a color. Light color is visible on the preview sphere, but you must be in Best Render mode to see its effect in the scene.

Intensity: Sets the strength of the selected light. Range = 0 to 2.0.

Intensity Curve: The intensity curve controls the intensity fall-off from the center of the light to the edge of its effect.

Global Ambient: Sets the amount of non-directional ambient light. Range = 0 to 100. Default = 15.

Note: The amount of ambient light is also set locally for each material in the scene. See the Material Palette.

Light:Type Subpalette

Sun: Infinitely far away, the Sun light illuminates the entire scene with parallel rays. The intensity of the light does not diminish with distance, so all objects in the scene receive an equal amount of light.

Point: The point light has a position in the scene and its intensity falls off with distance, so objects further away from the light are illuminated less. Omnidirectional, it casts rays in all directions

Spot: Illuminates in the same manner as the point light, except that it has direction. Place the light as described previously to control direction.

Glow: Illuminates all objects within the radius of the light equally, regardless of the direction they are facing.

Sun

Point

Spot

Glow

Radial: Usual light behavior is to light the areas facing the light brighter than areas facing away from the light. The Radial light illuminates the areas facing away from the light. This makes it a perfect “fill” light when placed at the same position as the main light.

Main light only (left), Main and Radial lights (right).

Main light only.

Main and Radial lights.

Light:Placement Subpalette

P: Click and drag from the position patch to the canvas and release to place a light. You can also enter the position of the light numerically with the Pos sliders.

X Pos / Y Pos / Z Pos: Use to set the x, y, and z positions of the selected light.

All three sliders above use a coordinate system where 0,0,0 is the center of the canvas. The X and Y values of +1 or -1 represent the outermost edges of the canvas. Z has a range of +4 to –4 because the total depth of the canvas is four times its greatest X or Y dimension. Thus, the default position is at the exact top center of the canvas and 1/4 of the total scene depth away from the camera.

Placement modifiers are disabled for sun lights, since they have no position.

Radius: Use the slider or click and type in the radius of the illumination. Range = 0.01 to 4.

Light:Shadows Subpalette

Shadow: Enable shadow casting for the light selected here. Global shadow casting must also be turned on to render shadows. See Render:Render Shadows.

Intensity: Controls the opacity of the shadow. Range = 0 to 100. Default = 75.

Length: Since ZBrush scenes are not fully 3D, there is no information about the back sides of objects. The shadow renderer treats all objects as if they had infinite depth and the length of the shadow is set here. Range = 10 to 500. Default = 50.

ZMode: A shadow-casting mode that does take object depth into account and produces superior results in some cases. If an object is only partially visible, it may not produce complete shadows.

Uni: The Unified Shadows slider reduces noise artifacts from standard ZMode shadows, producing more unifed shadows and faster rendering.

If the Rays slider is set to a small value, this can produce more painterly shadows.

This slider is active only when the ZMode button is pressed.

Blur: Determines how crisp or soft the edges of the shadow are. Higher values result in softer edges. Range = 0 to 7. Default = 4. ----

Rays: Activates the Global Shadows feature by specifying the number of shadow-casting rays that are used to evaluate each pixol of a shadow. Higher values result in more accurate shadows, but with an increased rendering time. For best results, ZMode should be active if the number of rays is set to higher than 1. Range = 1 to 500. Default = 1.

Aperture: Affects the sharpness of shadow edges by simulating a narrow or a broad stream of light for each ray. Higher values result in wider light rays and softer shadow edges. Range = 0 to 180. Default = 90.

Note: The following points apply:

• The higher the number of rays, the lower you will usually want your Aperture to be set to. For example, 500 rays at the default Aperture will cause the shadows to all but disappear.
• It is recommended to set a scene’s lighting up with only 1 ray in order to allow quick adjustments. ZMode with only one ray will often result in unusual light artifacts such as holes in the shadows. Don’t worry about this. When you are satisfied with the lighting, increase the number of rays and decrease the shadow Aperture before doing your final render.
• Material such as with the Diffuse Curve shown can result in extraordinary renders when used in conjunction with Global Shadows.