Rough transparent material

Description

../../../_images/roughtransparent.jpg

Example of rough transparent sandblasted soda-lime glass

Material This model corresponds to rough reflective and refractive materials. It works similarly to the specular material type, except the surface is rough, and causes scattering.

Rough transparent materials are often used with a bulk medium (see modelling volumes) : this means they do not describe only surface properties, but also what happens to light within their volume. The medium associated to the material governs refraction, and volumetric light extinction.

Reflection and transmission coefficients are governed by the defined intlaw. This can range from simple fresnel law (assuming the material is a simple diopter between internal and surrounding medium) to complex optical surfaces.

This material model is one of the most complex handled by Ocean. Simulations can take a significant time to resolve, as they generate a very large number of significantly contributing paths, taking into account roughness, polarization, refraction and dispersion, combined with advanced interface laws such as coatings.

For modelling a non-transparent rough surface, please refer to reflective material type. rough transparent<roughtransparent>` and specular material types.

Children Nodes

Interface law intlaw Optical law governing reflection and transmission coefficients
Roughness roughness Surface microscopic roughness distribution
Medium bulk The bulk medium (see modelling volumes) filling the geometry volume on the back side
Normal shader bump Normal shading modifier
Emitter emitter The Surface light emission properties

Parameters

name type description
rereflections boolean If set to true (by default), Ocean simulates first order rereflections on the roughness. This is more accurate, but slower. The effect is more visible with very rough surfaces
polarized boolean If set to true (by default), Ocean computes accurate polarization state for reflections/refractions. When set to false, a faster, more simple yet less accurate unpolarized model is used for this material

Ocean XML 3.0 example

<material name="frostglass" type="roughtransparent">
   <medium name="bulk" precedence="10" type="simple">
      <spectrum name="n" type="cauchy" b="1.5235" c="0.00424672"/>
      <spectrum name="a" type="tabulated" start="380E-9" end="780E-9" num="41">
         13.93       8.53    5.21    5.44    6.05    5.72    5.76    5.43    5.10
         4.02        2.77    3.32    3.92    3.78    3.97    3.27    2.90    3.31
         3.87        3.91    4.84    5.63    6.01    6.80    7.75    8.51    9.13
         10.28       10.85   11.67   12.65   14.02   14.81   16.04   17.04   18.25
         19.06       19.92   21.14   21.97   23.21
      </spectrum>
   </medium>
   <prm rereflections="true" polarized="true"/>
   <intlaw name="intlaw" type="fresnel"/>
   <roughness name="roughness" type="phong">
      <scalarshader name="exponent" type="uniform" value="10"/>
   </roughness>
</material>