User manual
© Next Limit Technologies 2010
Maxwell Render 2.5 User Manual
Chapter 10. Maxwell Materials | 69
Bump and Normal Mapping
This parameter, much like the Roughness parameter, allows you to simulate grooves and
imperfections on a surface, but at a much larger scale. For example, you can use a bump/
normal map to simulate wood grain. Keep in mind that Bump/ Normal mapping only
simulates these grooves on the surface; it does not actually create the geometry in any
way, like Displacement does.
Specify a Bump texture and the Bump strength. Brighter values in the texture will create
bumps on the surface and darker values will create indents. You can use a color map as
a bump map but only the grayscale information of the map will be used. Bump mapping
can be a sensitive parameter and standard values should be around 1 – 25. A bump map
with more contrast will produce a stronger effect, so the required bump strength depends
on the particular map and the look you are after.
There is an additional option to specify a Normal map as a Bump texture. While a grayscale
bump map can simulate only the up/ down direction of the grooves, a normal map has
the additional advantage of specifying an angle, or the direction of the grooves. It is
recommended to use a Normal map if you want to give the impression of very strong
bumps/ grooves on a surface, or even to create a brick wall. A bump map is usually
enough for smaller bumps, but if you are trying to simulate bumps that are too large just
raising the bump strength of a bump map, that may not be enough.
F.01 Normal mapping F.02 Bump mapping
A normal map is a RGB texture, not grayscale. Each channel species an angle and the
strength for the bump. Most modeling applications have an option to create a normal
map from a detailed model, and there are also applications that allow you to convert a
grayscale bump map into a normal map. When loading a normal map in the texture picker,
the options Flip X, Flip Y, and Wide specify how the normal map was created. The most
common standard is ‘Flip Y’, so this is selected by default. Consult the application you use
to create normal maps to nd out which of these options it uses to generate the maps.
10.04.03 SubSurface Properties
Subsurface Scattering (SSS) simulates the effect of light entering a translucent object
and scattering inside it. Some of this light is absorbed and some is scattered back to the
surface. SSS is a crucial component that allows you to accurately simulate many kinds of
materials including plastics, marble, milk, skin etc.
Incoming Ray
Scattered Ray
Internal Reflection
Refracted Ray
Scattered Ray
F.01 Surface Scattering
Particles
Scattered Ray
Scattered Ray
Incoming Ray
F.02 Sub-Surface Scattering