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Adding Fog and Haze
Fog and Haze are two atmospheric effects that can add realistic depth to your scene. Fog can make objects appear to disappear the farther they get from the camera. Haze can add the illusion of a distant horizon. The Fog and Haze controls in the Sky & Fog palette let you control the color and intensity of these effects.
Fog
Fog can add an element of sensuality, mystery, and even realism to your scenes. It acts like a thin layer of cloud close to the ground. Using Fog you can create the illusion of depth without having to add distant objects.
You can set intensity, height, and color attributes for the fog.
The fog acts as a global layer covering the entire scene. Its color and intensity are the same throughout the scene.
To set the amount of Fog:
1 Display the Sky & Fog palette by clicking the Sky & Fog text button.
2 Drag horizontally inside the Fog thumbnail to increase or decrease the amount of fog in your rendered scene. Drag to the left to decrease the amount of fog, and to the right to increase it.
To set Fog height:
1 Display the Sky & Fog palette by clicking the Sky & Fog text button.
2 Drag vertically inside the Fog control to increase or decrease the height of your fog. Drag up to increase the height and down to decrease it.
The height and amount values are displayed in the Text area of the Control palette as you drag.
To set Fog color:
1 Display the Sky & Fog palette by clicking the Sky & Fog text button.
2 Click the color swatch beneath the Fog thumbnail and choose a color from the color picker.
To set Fog attributes numerically:
1 If it's not already visible, display the Sky & Fog palette by clicking the text item on the menu bar.
2 Click the Sky Lab button. The Sky Lab dialog appears.
4 Click the Fog Density and/or Thickness fields, then enter a value. These fields set the amount of fog rendered in your image. The range is 0 to 100%, and the default value is 0%.
5 Click the Base Height field, then enter a value. This field sets the height of fog rendered in your scene, assuming there is a value greater than zero in the Fog field. The range is 0 to 100%, and the default value is 0%. It translates the entire atmospheric effect up or down without changing the density or thickness.
Base Height provides control over density at low altitudes, such as in valleys. In earlier versions of Bryce, you had to move the entire scene up or down relative to the atmosphere.
Blending the Fog Color
Since the fog remains constant throughout the scene, you may get some odd looking results when you're creating a sunset or sunrise. In these cases the sun is very close to the ground plane where the fog exists, so the fog should react to the sunlight. The Blend with Sun feature lets you create exactly this effect. As the sun approaches the Fog, the color and intensity of the fog changes to interact with the color of the sun.
To link Fog color to the Sun controls:
1 If it's not already visible, display the Sky & Fog palette by clicking the text item on the menu bar.
2 Click the Sky Lab button. The Sky Lab dialog appears.
4 Click the Blend with Sun button.
5 Make sure the Blend Fog button is enabled.
6 Enter a value in the Color field, or drag the slider, to set how much of the fog color is blended with the sun.
7 Enter a value in the Luminance field, or drag the slider, to set the intensity of the fog color when it's blended.
To get the best effect, set both these fields to 100.
Localized Fog
There may be times when you want to create localized pockets of fog. For this type of effect you'll need to use an object with a volume material applied to it; this way the object looks like fog. The area covered by the fog is then controlled by the size of the object. A flattened sphere usually makes a good fog volume.
This technique can also be used to create visible smoke, or gas.
To create localized fog:
2 Click the Sphere tool. A sphere object appears in the scene.
3 Squash and stretch the sphere, until it is the desired shape. Refer to "Transforming Objects" for more on transforming objects.
4 With the object selected, click the M icon that appears next to its bounding box. The Materials Lab appears.
5 Click the Volume button at the top of the lab.
6 Set up the values for channels in the material. Refer to "Building Materials" for more on creating materials.
- Choose a cloud-like texture from texture components. Stratus, Cumulus or one of the CloudBump textures work well.
- Pay special attention to the Base Density channel as this sets the transparency of your fog.
- You need to set a high value for the Edge Softness channel to blur the edges of the sphere object.
7 Click the OK icon to exit the lab.
8 In the Working window, move the object to the area where you want the fog to appear.
Haze
Haze is the natural effect you see when a plane (like the ocean) stretches out towards the horizon. At this distant point a different color appears over the horizon and light becomes fuzzy.
The Haze control lets you set the intensity and color of the Haze effect in your Bryce scene.
With haze set to zero, your horizon will have an unnaturally hard edge. Also note that the Cloud Altitude control will affect the height of this band of haze. The higher the altitude of the atmosphere, the wider the band of haze at the horizon.
Haze is applied to the entire scene equally. The haze always appears at the horizon.
To set Haze intensity:
1 Display the Sky & Fog palette by clicking the Sky & Fog button at the top of the Bryce window.
2 Drag horizontally inside the Haze thumbnail to increase or decrease the degree of haze in your scene. Drag to the left to decrease the amount of haze and to the right to increase it.
To set Haze intensity numerically:
1 If it's not already visible, display the Sky & Fog palette by clicking the button at the top of the Bryce window.
2 Click the Sky Lab button. The Sky Lab dialog appears.
5 In the Haze area, enter values in the Haze Density, Thickness, and Base Height fields. These fields govern the amount of haze rendered into your scene. The range is 0 to 100, and the default value is 4.
Density controls density of the lower part of the atmosphere, and affects the scattering of light around the sun.
Thickness scales the whole atmosphere up or down, with the density at "sea level" remaining unchanged.
Base Height provides control over density at low altitudes, such as in valleys. It translates the entire atmospheric effect up or down without changing the density or thickness. In earlier versions of Bryce, you had to move the entire scene up or down relative to the atmosphere.
To set Haze color:
1 Display the Sky & Fog palette by clicking the Sky & Fog button at the top of the Bryce window.
2 Click the color swatch beneath the Haze thumbnail and choose a color from the color picker.
Fog and Haze colors should be the same, or almost the same. For realism, the haze should be a little brighter and bluer than the fog. At nighttime, you have less illumination, so an effective nocturnal haze color could be dark blue-gray.
Blending the Haze color with the Sun
Since the Haze always appears at the horizon it should change color as the sun sets or rises. The Blend with Sun feature lets you simulate this effect. When the two elements are linked, the haze color and brightness change depending on the position of the sun. This creates very realistic looking sunsets.
When you're using this feature to create sunsets, you should choose the haze color carefully so as to create a natural-looking color scheme.
To link Haze to the Sun controls:
1 If it's not already visible, display the Sky & Fog palette by clicking the text item on the menu bar.
2 Click the Sky Lab button. The Sky Lab dialog appears.
4 Click the Blend with Sun button.
5 Make sure the Blend Haze and Blend Fog buttons are enabled.
6 Enter a value in the Color field, or use the slider, to set how much of the haze color is blended with the sun.
7 Enter a value in the Luminance field, or use the slider, to set the intensity of the haze color when it's blended.
8 To get the best effect, set both these fields to 100.
Setting the Color Perspective
Color perspective is the change in color with distance that characterizes the appearance of distant scenes in Nature: Dark areas turn blue and light ones yellow to orange to red. In Bryce you can make things change any color you like with distance. Color perspective is half of aerial perspective, while the other half is the loss of contrast with distance.
Color perspective controls the rate at which the red, green and blue components of the atmosphere come in with distance. In Nature, the atmosphere is white or a pale shade of gray. The blue component of that shade comes in faster than the green, which in turn comes in faster than the red. This is because the Earth's atmosphere scatters blue light more efficiently than green, and red least efficiently of all. The net result is that as a dark area recedes into the distance, it will turn blue before it turns white or pale gray in the far distance. Similarly, white areas will turn yellow, then orange, then red with increasing distance. The default values of color perspective are very delicate: if you change them, expect unpredictable results!
To set the color perspective:
1 If it's not already visible, display the Sky & Fog palette by clicking the text item on the menu bar.
2 Click the Sky Lab button. The Sky Lab dialog appears.
4 Click the Color Perspective button.
5 Click the RGB controls to control the rate at which the red, green, and blue components of the atmosphere come in with distance.
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