User manual
© Next Limit Technologies 2010
Maxwell Render 2.5 User Manual
Chapter 10. Maxwell Materials | 76
As in the previous example, start without setting the reectance and roughness. This will
help you see the balance between transmittance and scattering. Your transmittance map
should probably be the color of the leaves’ texture. A leaf is not thick so make sure you
do not set attenuation too high. 250 mm (1/4 m) is a good value to begin with. Turn on
Single Sided and initially set a reasonable thickness like 0.5 mm (1/2 mm). You can leave
scattering color to grey/ light green and set the coefcient to 1000. This is sufcient to
obtain a simple translucent green leaf material. Now, lter, using the leaf texture, and
scatter a uniform color using the given virtual thickness. This is not enough yet to actually
create a real leaf so let’s move on to the next step.
As can be seen on the right, the same single texture is normally enough to map all the
required slots. It is easy to create suitable versions of the same map by altering the image
properties under Texture Controls.
Transmittance and Scattering maps are responsible for the nal color of the material, while
reectance maps, roughness maps and bump maps are responsible for the speculars on
the leaves’ surface. If you do not change the settings of the speculars – as described in
the previous example – the result will be similar to Figure 14. Without reectance and
roughness applied, the result is similar to Figure 13. With all parameters set, your result
will be similar to Figure 15, which is what we are looking for.
F.13 The nal look F.14 No speculars F.15 Speculars only
Thickness is a new concept in this example. Because your geometry has no modeled
thickness, this parameter tells Maxwell Render the thickness it should assume for the
given surface. A real leaf has no uniform thickness and is thicker in veins and thinner
in other parts, so we had to map the thickness. The thickness map will show enough
contrast with a range starting at 0.2 mm for the thinnest areas and ending in 2.5 mm for
the thickest areas.
Even though it works the same, Asymmetry plays a more important role in Single Sided
SSS because it has a quicker and more obvious effect. A negative value will make the
leaves more translucent when they are backlit. So a tracing paper would have a high
negative asymmetry, while a normal paper would not.