Graphics Reference
In-Depth Information
We divided the material creation process into the three stages, corresponding to the
three layers/spheres. First, we built the more complex of all the three shaders that is the
Surface material:
F
From step 1 to step 8, we built the shader for the continents—simple image textures
connected as color factors to a Diffuse BSDF and Glossy BSDF shaders. From step 9
to step 13, we made the basic shader for the oceans.
F
In steps 14 and 15, we split the continents component from the oceans using the
Earth-spec
map, a black-and-white image working as a stencil for the factor input
of the Mix Shader_Surface node. We also connected the
Earth-color
map to the
SEAS diffuse shader to bring color back to the oceans.
F
From step 16 to step 19, we added a ColorRamp node to the SEAS frame, driven by
a Facing fresnel node. This was done to enhance the color of the water's specularity
(according to what NASA's satellite photos often show). A deep blue color was mixed
with the color image map by a MixRGB node. Thanks to the Facing fresnel node,
the blue color was mapped on the mesh faces perpendicular to the point of view,
resulting in darker water masses towards the center of the Earth sphere.
F
From step 20 to step 23, we built the night shader. The Earth-night image was
clamped (contrasted) by a ColorRamp node, and the resulting brightness values
were multiplied by a reddish color in the MixRGB node. All of this was then assigned
to an Emission shader. The night side of the Earth surface shows only in the shadow
part of the sphere thanks to the Empty_terminator trick.
F
From step 24 to step 27, we built the day/night terminator stencil.
F
Then, from step 28 to step 36, we built the
Clouds
layer on the second sphere.
We added more variety to the single
Clouds_low.png
image by superimposing
and offsetting (the mapping rotation of) a copy of the same cloud image.
F
From step 37 to step 47, we built the
Atmosphere
layer on the third (bigger)
sphere, with the Fresnel atmospheric effect and the reddish terminator.
As you have probably noticed, we didn't use any Texture Coordinate or Mapping nodes to
map the image maps. This is because the UV Spheres had been unwrapped with Image
Texture nodes. The existing UV coordinate layer was automatically taken into account by
Cycles for the mapping.
For the ocean bump, which was obtained by the Noise procedural, the Generated mapping
option was automatically used.
Thanks to the Damped Track constraints, which were targeted to the position of the Sun lamp,
we could use the Empty_terminator object as a UV coordinates projector for the day/night
division on the planet surface and for the red colored transition zone (the red terminator) in
the
Atmosphere
layer.
