Cycles nodes that model incorporating light passing through the objects interacting with them. One of these models is called shader calculation “Volume absortion”, it is especially suitable for working with transparent objects (used in combination with the shader “Glass” inter alia) o simular humo y nubes.
Such shaders may be used for the global space of the scene, decreasing with distance illumination, or objects independently as discussed below.
Volume absorption works, as the name says, absorbing the light which passes through a given volume.
Volume Absorption will absorb part of the light as it passes through the volume. This can be used to shade for example black smoke or colored glass objects, or mixed with the volume scatter node. This node is somewhat similar to the transparent BSDF node, it blocks part of the light and lets other light pass straight through. (Wiki Blender)
We can see in the picture below how the material is configured to run a test render. The color of the object defined in the node “Glass” (Red) while node “Volume absorption” uses a white color to add to the effect that the purpose of incorporating the right channel volume rendering.
The result can be seen in the following image in which the object is left only a shader “Glass” (transparent) while the right adds a “Volume Shader” in channel volume Object, saturating the color of it.
Changing the color of the object (white giving a transparent object left) and the spectrum of light absorbed (red hue provide the shader object that incorporates this right), obtain an interesting shade next to many liquids.
The result in this case is distinctly different.
Usamos a negative value for the density of absorption, the object will emissive, Further bringing light to the color chosen for the absorption. If we use a mixture of green and blue for the absorption, the result is emitted red (complementary).
With this configuration we shader therefore an environment bathed in the light emitted by the object that adds volumetric shader negative density.
- Volume Rendering for Artists
- RENDERING THE PHENOMENA OF VOLUME ABSORPTION IN HOMOGENEOUS TRANSPARENT MATERIALS
- Volume (Blender Wiki)