8

Environment Textures

Environment textures simulate three-dimensional spaces by either using a series of image files (Ball, Cube, and Sphere textures) or using a computer graphic procedure (Chrome and Sky textures). Typically, you map an environment texture to the environment as a background for your scene, or to a shader to simulate environmental reflections.

Do not map an environment texture to a shader's Bump or Displacement parameter. An environment texture mapped to Bump will produce unpredictable results. An environment texture mapped to Displacement will be ignored.

In This Section:

• Environment Texture Parameters 106
• Environment Texture Types 107
• Ball Texture 108
• Chrome Texture 114
• Cube Texture 117
• Sky Texture 118
• Sphere Texture 125

Environment Texture Parameters

The Color Balance, Blur, Effects, and 3D Placement parameters are common to all environment textures.

Color Balance, Blur, Effects

See Texture Parameters on page 101.

3D Placement

Texture Node

The name of the texture's Texture Placement Object. The Texture Placement Object is easier to find in the SBD window if you know its name. See Texture Placement Objects on page 96.

Environment Texture Types

There are several different types of environment textures: ball, chrome, cube, sky, and sphere.

Ball Texture

The Ball texture uses an image (or a series of images) of a highly reflective chrome ball in an environment (real world or computer generated) to re-create that environment. See Ball Texture on page 108.

Chrome Texture

The Chrome texture simulates a showroom environment. See Chrome Texture on page 114.

Cube Texture

The Cube texture simulates an environment by mapping six image files onto the inner surfaces of an infinite cube. See Cube Texture on page 117.

Sky Texture

The Sky texture simulates a planetary environment viewed from the surface of a planet. See Sky Texture on page 118.

Sphere Texture

The Sphere texture simulates an environment by mapping a texture or image file directly onto the inner surface of an infinite sphere. See Sphere Texture on page 125.

Ball Texture

The Ball texture uses an image (or series of images) of a highly reflective chrome ball in an environment (real world or computer generated) to re-create that environment. This is possible because the reflections in the chrome ball provide a (nearly) 360 degree view of the environment.

A Ball texture background renders faster than a procedural texture background or a background modeled with surfaces. You can therefore replace a complex background with a Ball texture (by rendering an image of a chrome ball in that environment) to reduce rendering times.

In order to use the Ball environment texture, you must map the texture's Image parameter with the image of a reflective chrome ball in the environment you want to re-create. You should also map the environment's Backdrop parameter with the image of the environment without the chrome ball.

To create an image of a chrome ball, first place a highly reflective chrome ball (sphere) in the environment (real world or computer generated) that you want to re-create. Place the ball at the exact location (in the original environment) where you want your model to appear (in the re-created environment), and take note of the ball's distance from any floor/walls/ceiling or large objects.

Photograph (or render) the ball using a telephoto lens, and take note of the camera's elevation (the angle between the camera's view and the environment's ground plane), and the camera's inclination (the angle between the camera's view and the environment's YZ plane).

The photo essentially contains a compressed sample of the entire environment, except for the area directly behind the ball. The highest resolution is in the direction of the camera, so the image provides the best data compression for that point of view.

A Ball texture that uses a single photograph of a ball has two limitations: the missing area directly behind the ball, and the decreasing resolution toward the edges of the ball. You can overcome these limitations by taking a series of photographs of the ball (up to a maximum of 32). The photographs must be taken on the horizontal plane of the ball (that is, not above or below the ball), at a constant distance from the ball, and at equal intervals around the ball. The Ball texture will automatically select the best image for any particular view (that is, no missing area and maximum resolution). Name the image files <filename>.1 through <filename>.n, where the files represent a sequence going clockwise around the ball when viewed from above.

Remove the ball from the environment, and photograph (or render) the environment again using the same camera position, elevation, and inclination, but a wider angle lens (for example, 24mm to 50mm).

The Ball texture can best re-create environments that have no objects in their center (that is, near the chrome ball). For example, rooms and interiors should not contain furniture, and outdoor scenes should not have trees or cars near the chrome ball. (In general, outdoor scenes can contain buildings).

If you are using a single image of a chrome ball, map a File texture to the Ball texture's Image parameter, and then map the image file of the ball in the environment to the File texture's Image parameter.

If you are using a series of images of a chrome ball, map a Volume texture to the Ball texture's Image parameter, and then map one of the image files to the Volume texture's Pix Sequence parameter. Set the Volume texture's From and To parameters to the extensions of the first and last image files in the sequence (1 and n).

Map the image of the environment without the chrome ball to the environment's Backdrop parameter.

Set the Ball texture's Inclination and Elevation parameters to the inclination and elevation of the camera used to photograph the ball.

For accurate reflections of the re-created environment on your model, set the Ball texture's Projection Geometry parameters to values corresponding to the distance between any floor/walls/ceiling or large objects and the chrome sphere when it was photographed.

To simplify the positioning of the environment's Backdrop image, set the Ball texture's Eyespace toggle ON. To model background geometry (for example, so you can add shadows, lighting effects, or fog to your scene), set the Ball texture's Reflect toggle OFF.

Ball Environment Parameters

Image

The texture used by the Ball texture. To use a single image of a highly reflective chrome ball in an environment, map a File texture to the Ball texture's Image parameter, and then map the image file to the File texture's Image parameter (see File Texture on page 151).

To use several images of a highly reflective chrome ball in an environment, map a Volume texture to the Ball texture's Image parameter, and then map one of the image files to the Volume texture's Pix Sequence parameter (see Volume Texture on page 222).

Inclination

The rotation (in degrees) of the ball image about the vertical axis. The valid range is -10000 to 10000. The slider range is 0 to 180. The default setting is 0.

Set the Inclination value to the inclination of the camera (that is, the angle between the camera's view and the environment's YZ plane) used to generate the image file (by photographing or rendering a reflective ball in an environment). For example, if the inclination of the camera is 45 degrees, set the Inclination value to 45. If the camera is parallel to the YZ plane, set the Inclination value to 0. When creating the ball image, a camera inclination and elevation of zero will provide the best resolution for the view you intend to use.

Elevation

The rotation of the ball image about the horizontal axis. The valid range is -10000 to 10000. The slider range is -90 to 90. The default setting is 0.

Set the Elevation value to the elevation of the camera (that is, the angle between the camera's view and the environment's ground plane: XY plane for a Z-up scene) used to generate the image file (by photographing or rendering a reflective ball in an environment). For example, if the elevation of the camera is 90 degrees (that is, it is directly above the ball), set the Elevation value to 90. If the camera is parallel to the ground plane, set the Elevation value to 0. When creating the ball image, a camera inclination and elevation of zero will provide the best resolution for the view you intend to use.

Eyespace

Causes the position of the Ball texture's Image file to be defined relative to the window, not the camera view. If Eyespace is ON, the Ball texture's Image file automatically matches the environment's Backdrop image file (provided they were both originally photographed/rendered from the same point of view), even if the camera view changes. Reflections, however, are based on the background being infinitely far away; that is, the reflection planes are ignored (see Projection Geometry below). Rendering is faster when Eyespace is ON. The default setting is OFF.

Reflect

Causes the Image file to be reflection mapped onto the background. If Reflect is OFF, the Image file is mapped using a solid texture spherical projection (see Projection Texture on page 191). This allows you to model the geometry of the background image and then map the background image to this geometry, for example, to add shadows, lighting effects, or fog to your scene. The default setting is OFF.

Projection Geometry

The Projection Geometry parameters define the location of the sky and/or room walls of the original environment so that the system can calculate reflections on surfaces in the re-created environment.

For example, if the original environment consisted of a ground plane and a sky, then you would set the Sky_radius value to the radius of the sky, and the Bottom value to the distance between the ground plane and the reflective ball. If the original environment consisted of a room, then you would set the Bottom, Top, Left, Right, Front, and Back values to the distance between each wall and the reflective ball.

In some cases you may want to use values different than the original environment. For example, instead of using the Bottom, Top, Left, Right, Front, and Back values to define the walls of a room, you may simply use the Sky_radius parameter. Because Sky_radius defines a sphere, reflections on surfaces in the simulated environment will be smoother and less likely to become blurred. You can also combine Sky_radius with Bottom, Top, Left, Right, Front, and/or Back.

Sky_radius

The radius of the sky of the original environment. The valid range is 0 to 100000. The slider range is 0 to 20. The default value is 0.

Bottom, Top, Left, Right, Front, Back

The distance between the reflective ball and each wall of the original environment. The valid range is 0 to ·. The slider range is 0 to 20. The default value is 0.

Chrome Texture

The Chrome texture simulates a showroom environment. The texture consists of a ground plane and a sky plane (with fluorescent style light rectangles), and provides a simple but effective environment to simulate reflections off chrome surfaces.

Sky Parameters

Sky_color

The color of the sky at the horizon. Overall sky color is linearly interpolated between Sky_color and Zenith_color.

Zenith_color

The color of the sky at the zenith (straight up). Overall sky color is linearly interpolated between Sky_color and Zenith_color.

Light_color

The color of the simulated fluorescent lights. These "lights" produce reflections in surfaces, but they do not actually illuminate surfaces.

Light Placement

The Light Placement parameters control the size and placement of the simulated fluorescent lights in the environment. These "lights" produce reflections in surfaces, but they do not actually illuminate surfaces.

Width, Depth

The width and depth of each light. These parameters also determine spacing between lights. The valid/slider range is 0 to 1. The default Width value is 0.5 and the default Depth value is 0.1.

Width_mult, Depth_mult

The number of lights per unit length. The valid/slider range is 0 to 1. The default value is 1.

Width_offset, Depth_offset

The light displacement. The slider range is 0 to 1. The default value is 0.

Floor Parameters

The Floor Parameters control the appearance of the environment's floor.

Floor_color, Horizon_color, Grid_color

The color of the floor, the floor's horizon and the floor's grid.

Real_floor

If Real_floor is OFF, the environment's floor is located at infinity, so reflections on moving objects and/or reflections viewed from a moving camera will be incorrect. The default setting is OFF.

If Real_floor is ON, the floor is located on the ground plane, so reflections on moving objects and/or reflections viewed from a moving camera will be correct. If Real_floor is ON, make sure surfaces and/or the camera do not go below the ground plane.

Grid Placement

The Grid Placement parameters control the size and placement of the floor's grid.

Width, Depth

The width and depth of the grid lines. These parameters also determine the spacing between grid lines. The valid/slider range is 0 to 1. The default value is 0.1.

Width_mult, Depth_mult

The number of grid cells per unit length. The valid/slider range is 0 to 1. The default value is 1.

Width_offset, Depth_offset

The grid displacement. The slider range is 0 to 1. The default value is 0.

Cube Texture

The cube environment texture simulates an environment by mapping six image files onto the inner surfaces of an infinite cube.

One of the advantages of the cube environment texture is that you can blur it without increasing rendering time.

Use Bluroffset to de-focus reflections when using the cube environment texture as a reflection map to simulate unpolished surfaces.

The advantage to Cubic environment maps is that they can be blurred by an arbitrarily large amount without any additional cost. When generating a background from an environment map, the amount of blurring required to prevent aliasing increases with the field of view. In practice, a 512² texture images and a field of view less than 90\xb0 , will result in very little blurring.

For reflection mapped surfaces however, the amount of blurring will depend on the surface curvature and the distance from the eye point. This cannot be computed automatically. Using the Blur_offset slider in the Blur window lets you de-focus the reflections by a desired amount (see Common Surface Texture Parameters for more information). In fact, soft focus reflections can be used to simulate less than perfectly polished surfaces.

Cube Environment Parameters

Right, Left, Top, Bottom, Front, Back

The image files mapped to the right, left, top, bottom, front, and back inner surfaces of an infinite cube. (The front of the cube faces the front orthographic window.)

Sky Texture

The Sky texture simulates a planetary environment viewed from the surface of a planet.

Sky Environment Parameters

Total_bright.

The overall brightness of the environment. The valid range is 0 to ·. The slider range is 0 to 5. The default value is 1.

Sun Parameters

Sun_bright.

The color and brightness of the sun. The default color Value is 0.5.

Halo_bright.

The color and brightness of the halo around the sun. The default color value is 0.1.

Elevation

The angle (in degrees) of elevation of the sun relative to the floor. The valid range is -10000 to 10000. The slider range is 0 (sunrise/sunset) to 90 (midday). The default value is 45.

Azimuth

The angle (in degrees) of the sun in the sky about a vertical vector. The valid range is -10000 to 10000. The slider range is 0 to 360. The default value is 145.

Size

The size (radius) of the sun. The valid range is 0 to 10000. The slider range is 0 to 20. The default value is 0.531.

Blur

The size (radius) of the halo around the sun. The valid range is 0 to 1000. The slider range is 0 to 20. The default value is 1.

Atmospheric Settings

Sky_bright.

A scaling factor applied to the sky color. The default color Value is 0.5.

Air_density

The density of the air in the atmosphere. The denser the air, the more light will be scattered. Think of air density in terms of low and high altitudes. High altitude skies are almost black straight up and blue near the horizon (the Air_density value less than 1). Low altitude skies are blue straight up and white near the horizon (the Air_density value greater than 1). The slider range is 0 to 3. The default value is 1.

Dust_density

The density of dust in the atmosphere. The slider range is 0 to 3. The default value is 0.

Sky_thickness

The thickness of the atmosphere. The valid range is 0 to ·. The slider range is 0 to 10000. The default value is 1000.

Sky_radius

The outer radius of the sky as a multiple of Sky_thickness. The Sky_thickness and Sky_radius values determine the planet radius, and planet radius influences the appearance of sunsets. A planet with a large radius will have very red (and very dark) sunsets (you can adjust Sky_bright to compensate for sunsets that are too dark).

For example, if Sky_thickness is 1000 and Sky_radius is 50, the outer radius of the sky is 1000 x 50 = 50 000 units, and the radius of the planet is (1000 x 50) - (1000 x 1) = 49 000 units.

The valid range is 0 to ·. The slider range is 0.01 to 300. The default value is 50.

Floor Parameters

The Floor Parameters control the appearance of the environment's planet surface.

Has_floor

Toggles the floor ON or OFF. If Has_floor is OFF, the environment below the horizon is a mirror image of the environment above the horizon.

Floor_texture

The color or texture of the floor. The default color value is 0.392.

Cloud Parameters

Cloud texture

The texture that determines cloud distribution in the sky. For example, the Fractal texture creates very realistic clouds. By default, there is no cloud texture map (and no clouds).

Cloud_bright.

The brightness and color of cloud illumination from ambient scattered light in the atmosphere. (The amount of ambient light depends on the Elevation value.) The default color Value is 0.5.

Sunset_bright.

The brightness and color of cloud illumination when the sun is below the horizon and the clouds are front lit (for example, when the sun's Elevation value is 0 and its Azimuth value is 180). This is a very subtle effect and occurs only briefly in nature during a sunrise or sunset. The effect is more noticeable with high altitude clouds. The default color Value is 1.

Density

The density of individual clouds. The valid range is 0 to ·. The slider range is 0 (no clouds) to 5 (heavy clouds). The default value is 1.

Threshold

A threshold value for the Cloud texture that controls how much of the sky is covered with cloud. As the Threshold value increases, darker areas of the texture do not produce clouds. The valid range is 0 to ·. The slider range is 0 (entire sky is cloudy) to 1 (no clouds). The default value is 0.5.

Power

The clouds are scaled and positioned by adjusting the Power option. The cloud density is achieved by subtracting the Threshold from the pixel value clipping to 0, then multiplying the result with Density. To control the amount of de-focusing of the Cloud_texture, adjust the Blur value (under Sun Parameters). The valid range is 0 to ·. The slider range is 0 to 1. The default value is 1.

Altitude

The height of the clouds. The Altitude value does not greatly affect the position of the clouds. Instead, it determines how much the atmosphere obscures the clouds near the horizon. Low altitude clouds disappear into haze much more slowly than high altitude clouds. The valid/slider range is 0 to 1. The default value is 0.2.

Halo_Size

The size (radius) of cloud illumination from direct back lighting by the sun (for example, when the sun's Azimuth value is 0). Direct back lighting is most noticeable near the edges of thick clouds or through thin clouds. The valid range is 0 to ·. The slider range is 0 to 50. The default value is 20.

Calculation Quality

The calculations required for curved atmospheres are expensive. The Calculation Quality parameters do not greatly affect the appearance of the sky, but do affect the speed at which the calculations are computed.

Sky_samples

The number of samples used above the cloud layer. Set the Sky_samples value to 1 for maximum speed. The valid range is 0 to 20. The slider range is 0 to 3. The default value is 5.

Floor_samples

The number of samples used by the atmosphere between the eye and the horizon. Increasing the Floor_samples value increases the effect of the atmosphere along the floor. The valid range is 0 to 20. The slider range is 0 (no atmosphere between the eye and horizon) to 3. The default value is 1.

Cloud_samples

The number of samples used below the cloud layer. The valid range is 0 to 20. The slider range is 0 (clouds do not fade to mist at the horizon) to 3. The default value is 5.

Sphere Texture

The Sphere texture simulates an environment by mapping a texture or image file directly onto the inner surface of an infinite sphere. The best way to create a sphere environment is to use a ramp texture and paint objects onto it, being sure to avoid the poles and edges.

Sphere Environment Parameters

Source texture

The texture mapped to the inner surface of an infinite sphere.

Shear_u

Shears the Source texture in the U direction. For example, horizontal stripes will resemble a barber pole. The slider range is -10 to 10. The default value is 0.

Shear_v

Shears the Source texture in the V direction. For example, concentric lines at the poles will spiral inward. The slider range is -10 to 10. The default value is 0.

Flip

Reverses the U and V orientation of the Source texture. For example, what was the horizon now spans the two poles. The default setting is OFF.