Creating Complex Natural Materials in Cycles - Blender 2.6 Cycles: Materials and Textures - page 186

cil for the factor input of the Mix Shader node. We also connected the
Earth-color map to the SEAS frame's Diffuse shader, to bring back color
to the oceans.
• From step 15 to step 18, we added to the SEAS frame, driven by a
Facing Fresnel node, a ColorRamp node to enhance the coloration of
the water's specularity (according to what often NASA satellite's photos
show) and a deep blue color mixed to the color image map by a Mix node.
Thanks to the Facing Fresnel, the blue color is mapped on the mesh
faces perpendicular to the point of view, thereby resulting in darker water
masses towards the center of the Earth sphere.
• From step 19 to step 23, we built the night shader. The Earth-night image
has been clamped (contrasted) by the ColorRamp node and the result-
ing brighter values multiplied by a reddish color in the Mix node. All this
is then assigned to an emission shader mixed at 50 percent with the rest
of the components of the surface shader. Because the emission value is
quite low, the "night surface" shows only in the shadow side of the Earth.
• Then, from step 24 to step 29, we built the Clouds layer on the second
sphere.
• From step 30 to step 35, we built the atmosphere layer on the third
sphere.
As you have probably noticed, we didn't use any Texture Coordinate or Mapping
node to map the image maps. This is so because the spheres have been unwrapped
and with Image Textures nodes the existing UV coordinate layer is taken automatic-
ally in account by Cycles for the mapping. For the ocean bump, instead, obtained by
the Noise procedural, the Generated mapping option is automatically used (if you
remember the section about the mapping of the textures in Cycles from Chapter 1 ,
Overview of Materials in Cycles ).